BULLETIN NO. A 10 (TECHNICAL)
Poisonous Plants Of Maryland
In Relation To Livestock
21150
1IIIIlUIIIIIIIIIIIIIIIIIII 1111 1111
JARJ
By
GEORGE B. REYNARD and
J. B. S. NORTON
The University of Maryland
Agriultural Experiment Station
College Park, Maryland
MAY, 1942
FOREWORD
Every yem' throughout its history the Experiment Station has been called on to assist those
who have lost valuable livestock because of plant
poisoning. Such happenings have always caused
the station much concern because of the helplessness of the owners. Although a brief account of
poisonous and injurious plants in Maryland was
published at the end of the Weed Bulletin in 1911,
this is now out of print. Following the urgent
request of the leaders in animal husbandry in our
state, several years investigation of the poisonous
plants of Maryland has been made, and the present Bulletin is issued with the belief that it wlll
be a useful guide to livestock farmers, veterinarians and agricultural leaders in saving the lives
of many valuable animals.
R. B. CORBETT,
May, 1942.
Di1'8ctor.
The University of Maryland
Agricultural Experiment Station
May, 1942
Bulletin No. A 10*
POISONOUS PLANTS OF MARYLAND IN
RELATION TO LIVESTOCK
INTRODUCTION
Reports of loss of live-stock in Maryland through poisoning
by plants found in the pastures have been received at the Maryland Agricultural Experiment Station for many years. Alrbhough
the losses have r3irely amounted to more than a few animals at
anyone <time, the continued occurrence of these cases and the
serious loss which sometimes comes to owners of only a few or
very valuable animals have prompted an investigation into the
situation. It has been the aim to determine which plants are
actually poisonous to live-stock in Maryland and to prepare descriptions of the plants and the cases of poisoning to aid veterinarians and stock-owners to reduce losses due to these plant
poisonings.
Recommendations for use of this bulletin
In the event cases of stock-poisoning have occurred in pastures
or woodland and the cause is unknowll, it may be that one of
the plants described here has been responsible for the losses.
The descriptions of actual illS'tances of poisoning in Maryland
should be read carefiully and any similarities to the cases in
question noted. In Table I, there are listed several plants COllsidered poisonous to stock and this should be looked over for
the llames of plants found in the pasture. The accompanying
illustrations from photographs or the descriptions of the different Idnds of poisonous plants should also be used in making a
survey of the conditions of the pasture. Any suspected ]Jlants
which cannot in this way be identified may be sent to the Experiment Station a:t College Park for identification.
*Cnntl'ihl1tion No. 1839 1\lnrylnncl A.~dC111hll'al ]~:xlwl'hllrmt
Botany) .
Station
(TleJlRl'\nll'nt of
249
250
THF. 1\lARYLANn AITRH'ULTlTRAL F.XPERDmNT STATION
Definition of a stock-poisoning plant
Stock-poisoning plants are those which when eaten may produce effects by chemical or other means resulting in sickness or
death or which without question do more harm than good to the
animal.
Conditions of poisoning
A plant may not be equally poisonous at all times. It is common observation that animals may be pastured in one location
for years without encountering any troubles from plant poisoning, Gnly to suffer losses without warning from 'this cause. The
lack of poisoning, therefore, cannot be taken as conclusive evidence of Ithe lack of poisonous plants in any given pasture. In
some cases, poisoning may occur only when more palatable, and
useful forage has been eliminated by grazing or by drouth or
other conditions unfavorable to plant growth and it is at these
times that particular attention should be given to the conditions
in the pastures.
It was observed in the present investigations that young animals were more of.ten poisoned than IDwture, and care should be
taken in introducing them to new pastures.
Cultivated plants have been found to cause numerous cases of
poisoning to stock. Many of the plants of the flower garden as
well as the vegetable garden are unfit for use by animals. It is
also true that several instances of poisoning have been produced
by trimmings of hedges and trees which have carelessly been left
where animals could eat them. Stock owners should become
acquainted with the various plants of this nature which are
potential sources of poisoning, and take steps to keep animals
from being poisoned needlessly. Even a casual Ireading of some
of the material induded in the following pages may prevent the
offering to stock of plants formerly thought to be harmless.
Inquiries at some farms showed that loss of animals from
"forage poisoning" was an experience which was not common
but which was to be expected "from time to time." With a little
extra caution. these losses can be greatly reduced or entirely
prevented if the effort of removing dangerous plants is made.
There is often an air of mystery surrounding cases of poisoning in view of the fact that animals formerly in excellent health
may quite suddenly be taken sick and die without apparent cause.
It is also true that causes other than poisonous plants are frequently responsible for those sudden losses and should always be
considered. Amon,g these other causes are lead-poisoning, usually
from the lead in paint which has been left in discarded cans or
is licked off newly painted walls, and plant sprays contajning
POISONOUS PLAN'l'S OF MARYLAND IN RELATION TO LIVESTOCK
25i
arsenic or other poisonings, which may be injurious to animals
eating the treated plants. Nitrate of soda is another potential
source of poisoning to stock as they may lick it up from piles left
within their reach. Other causes of death include pieces of wire,
glass or nails which the animals may 'have eaten along with their
feed and it is usually only by a post mortem examination that
this is, discovered.
It should be emphasized that 'the post mortem is f'requently a
valuable aid in clearing up some of the cases of repeated stock·
poisoning by plants, as it is sometimes possible to determine
from the contents of the stomach, which plants have been eaten.
This information is also of luse in determining whether some of
the forei,gn objects mentioned above may be the actual cause of
the injury. A great many cases, thought at first to be poisoning,
turn out to be infection diseases.
PROCEDURES FOLLOWED IN THIS INVESTIGATION
In the initial stages of the present investigation, after a pre·
liminary list of probable poisonous plants had been made, a
form was sent to veterinarians practicing in Maryland. This
form included the list of suspected plants and requested infoI'·
mation as to which of the plants had been responsible for actual
cases of stock-poisoning in the experience of the veterinarians
reporting from the various localities. A request was made for
information about plants not included on the list but which were
recorded by the veterinarians as having caused poisoning.
Twenty-six completed forms were returned, these representin,g areas in practically all major sections of the State. Personal
inquiries were made of these veterinarians and others in the
State to >confirm reports of poisoning and to locate the various
farms on which the trouble had occurred.
From the instances located in this manner and from those
repof\ted directly to the University or to the Maryland State
Livestock Sanitary Service Laboratory at College Park, the additional information helped to broaden the SCOpe of the investigation. Numerous trips were made to, various parts. of Maryland,
each 'county being visited at least twice, and thorough surveys
of conditions in pastures, especially those in which poisoning of
stock was said to have occurred, were made with the purpose of
determining which plants could have been responsible for the
trouble. In a number of cases it was possible to visit the farms
in question immediately following the poisoning, or even in the
midst of a series of poisoning 'cases and in this way some cases
of poisoning were more quickly cleared up by determining the
plants responsible in the individual cases.
252
THE :MARYLAND AGRICULTURAL EXPERIMENT STATION
No experimental work was done here with treatments for the
various types of plant poisoning of live-stock. Some treatments
have been suggested in cases in which it was thought a remedy
found successful by other investigators might be of value in
Maryland. Unfortunately many of the types of poisoning resluJting from toxic plants have as yet not been clearly described as
to symptoms and successful treatments by any authorities. However, special care was taken to include any 'remedies which have
been tried and found successful by veterinarians practicing in
the State.
PLANTS WHICH HA VE CAUSED STOCK-POISONING IN
MARYLAND AND D<ESCRIPTIONS OF THE
CASES OF POISONING
Other important poisons are discussed later in the sections on
prussic acid poisoning, photosensitization, etc. The plants are
described in order of their importance as poisons, in each of
these sections, with some of the minor related ones grouped
under the more important species.
Mountain laurel, ivy, or bank laurel, Kalmia latifolia L.
This beautHul shrub is found abundantly in the mountainous
sections of western Maryland and in acid soil in scattered locations throughout the rest of the State. It is a member of the
heath family, has leathery leaves, and showy, pink to white
flowers which appear in early summer. In the mountains it often
may form dense thickets up to about twenty feet in height. Since
the leaves are evergreen, the plants often form one of the few
sources of green foliage for animals in the mid-winter months
and it is at this time that many of the cases of poisoning occur.
More than twenty separate instances of poisoning of stock by
the mountain laurel have been recently recorded. The cases usually have involved sheep but also included cattle and in a few
cases, goats. Poisonings occurred in twelve of the twenty-three
counties of Maryland and for this reason the laurel is considered
one of the major causes of stockwpoisoning in the State.
A few instances may serve to indicate the nature of the injury
which has resulted from these cases. In Allegany County several
cases of the death of sheep and cattle are on record and a few
instances of the death of sheep and cattle are recorded from
Baltimore County. Sheep have also been severely poisoned or
were killed in Carroll, Cecil, Charles, Frederick, Garrett, Harford, Kent, Montgomery, Queen Annes and Talbot Counties. In
POISONOUS PLANTS OF :MAl{YLANb IN RELATION TO LIVESTOCK
FIG. 1.
FIG. 2.
Mountain lau?'el (Kalmia latifolia).
Great lau?'el, Rhododendron, (Rhododendron maximum).
253
254
THE lIIARYLAND AGRICULTURAL EXPERIilIENT STATION
one case in Talbot County several goats had been kept for some
time in a wooded pasture and had finally 'beg;un eating fr~ely
from the bank laurel which was present. They soon became SIck,
were at first quite active, later exhibited nervousness and finally
lay down on the ground. They became quite inactive, had persistent nausea and vomiting and remained in this state for several
hours before death. In another case, in Cecil County, in the
winter months a dozen sheep were killed from eating abundantly
from the foliage of the laurel.
That goats are susceptible to this poison was also found in the
classic example which occurred several years a,go in Baltimore.
Here two very valuable trained goats died after browsing on the
mountain laurel decorations which were used on the stage where
they were performing. Previous to this, in 1895, a monkey was
killed in the Washington, D. C., zoo by eating the laurel leaves
kindly offered by a visitor.
Symptoms of poisoning as given by investigators in the United
States Department of Agriculture (Marsh and Clawson), specifically for poisoning of sheep are as follows: "depression, weakness shown in staggering gait, and sometimes prostration, salivation, nausea, accompanied by vomiting, irregular and sometimes forced respiration." It is of interest that some of the
symptoms of poisoning shown by the goats poisoned in Maryland closely parallel the above.
The toxic principle is stated by several investigators (o!'i.ginally by Plugge) to be andromedoto,xin, a poisonous resinoid which
is also found in some other members of the Heath family. Certain of these plants are found in the State and although with
the exception of the last named they have not found responsible for definite instances of poisoning, are listed here as possible offenders: Rhododendron (Rhododendron maximum L.), dog
laurel, fetter bush (Leucothoe racemosa (L..) Gray), stagger
bush (Lyonia mariana (L.) D. Don.), male berry (Lyonia ligustl'ina (L.) DC.), sheep laurel (Kalmia angustifolia L.).
The sheep laurel or lambkill is found in many sections of the
State but is not as abundant as the mountain laurel. The former
plant is much smaller and is characterized by its smaller, narrower leaves and by its pinkish flowers which appear in clusters
a few inches from the ends of the flowering branches. The plants
were found to have C3msed poisoning and death of a number of
sheep which ate the foliage.
POISONOUS PLAlIlTS OF lIfARYLAND IN RELATION TO LIVESTOCK
FIG. 3.
Young water hemlock plant showing bulbous TootS.
255
256
THE 1I1ARYLAND AGRICULTURAL EXPERIlIIENT STATION
FIG. 4.
Poisonous water hemlock (Cicuta maculata). Plant
in flower, showing small umbels of flowers and the
divided leaves.
Water hemlock, Cicuta maculata L.
On at least ten occasions in widely separated locations in the
State, animals have been poisoned by eating parts of this very
dangerous 'plant. The cases include poisoning especially of young
calves, but also of cattle, sheep and in single instances a mare
and a colt.
On one farm in Montgomery County five calves were turned
out in a pasture for their first time and one by one died, each
exhibiting symptoms suggesting a violent poison. They had all
been found in the pasture, in a low marshy section, where it
was found they had been eating from a patch of vigorously
growing water hemlock plants. The plants were growing with
marsh grasses and sedges and were not as conspicuous as they.
are later in the season when in flower. The quick action of the
poison which was reported for the cases above, and the accompanyin,g convulsions are both typical of poisoning by these plants.
The calves had made marks with their front hoofs, indicating
some struggling after they had fallen. This series of deaths is
POISONOUS PLANTS OF MARYLAND IN RELATION TO LIVESTOCK
257
typical of others which were found to have occurred in other
sections of the State.
The poisonous water hemlock is found in all sections of Maryland. It grows only in locations which are quite wet at least part
of the year, such as marshes, along streams or ditchbanks or'at
the edges of small ponds. It is a member of the Umbelliferae or
Parsley family, and has showy umbels of minute white flowers.
The leaves are large and divided into many leaflets and the base
of the leaf partly encloses the stem from which it grows. If the
mature plants are pulled up there will be seen the duster of
tuberous roots which show an oily, yellow substance upon being
cut open. It is in this substance that the toxic principle, a resinoid, cicutoxin, is most concentrated. Another feature which
serves to identify the plants is the presence of closely-spaced
cross partitions in the stem at its base. This feature was noted
in practically every plant observed in this study but is not an
exclusive feature of the poisonous water hemlock.
The poisonous nature of this plant is known throughout the
country, in fact throughout the world, and in the event it is
found in the pastures, it should certainly be pulled up and the
whole plant destroyed by burning. The la'tter is especially important as even small parts of the plant, especially the tubers, are
sufficient to, ,cause the ,death of live-stock or even of children who
might in curiosity eat any parts left lying around. Early in
May, 1937, two children who had tasted the roots of some water
hemlock plants were made severely ill and in all probability were
saved from death only by prompt treatment at a hospital in
Allegany County.
Poisoning of stock 'by the cicutoxin in the plant is chiefly
brought on by the action of this subs,tance on the central nervous
system of the animal and may be accompanied by nervousness,
salivation, wild running, involuntary muscular movements and
later convulsions and death. Unfortunately there is no known
specific antidote, and the quick action of the poison mi,ght readily
prevent the use of one. However, the best procedure is prevention
by removal of the plants, and a survey of the pasture may well
repay the effort.
Star-of-Bethlehem or Snowdrop, Ornithogalum umbellatum L.
Numerous instances have been recorded in which sheep have
been killed from the effects of ea'ting bulbs of the snowdrop
which were lying exposed on the ground. This type of poisoning
has been restricted to five or six counties on the Eastern Shore
and one in Southern Maryland. In the former section of the
State, near Christmas time in 1935 over a thousand sheep were
258
THE MARYLAND AGRICULTURAL EXPERIMENT STATION
FIG. 5.
FIG. 6.
Snowdrop, 01' Star-of-Bethlehem (Ornithogalum umbellatum).
Bulbs of Ornithogalum umbellatum.
losrt from poisoning caused by the bulbs of this plant. At this
time it had been snowing, later rain had melted the snow and
exposed the bulbs which were lying in among the grass or winter
wheat. The sheep had been turned out at this time and the injury
appeared soon after.
Comments received from Dr. F. S. Wharton, D. V. M., of Centerville, Maryland, in correspondence, follow: "Sheep exhibit
marked depression, salivation and pronounced bloating. I have
never found a successful treatment. The bulbs appeal' to be the
POISONOUS PLANTS OF MARYLAND IN RELATION TO LIVESTOOK
259
only part of the plant that is poisonous and they seem to have
to be in a wilted stage as in winter afiter they have been frozen
and are thawing out, or in summer when they have been plowed
up and the sun shines on them."
Although some doubt is occasionally expressed that the bulbs
are actually poisonous, the repeated occurrences of poisoning of
sheep following ,consumption of the bulbs leaves little doubt in
the minds of the stoIJk owners. It is true, however, that the bulbs
are at times eaten without apparent ill effects.
Reports from the Indiana Experiment Station state that the
bulbs have caused poisoning of cattle in that State. Certain other
species of Ornithogalum have been definitely recorded as stockpoisoning plants by investigators in South Africa. There the
plants have been responsible for the death of cattle, horses,
sheep, do,gs and other animals and controlled experiments in
which animals were drenched with whole, fresh plant mixtures
have shown that death is not infrequent from this treatment.
Although the actual poisonous principle has not as yet been
isolated and identified in the species growing in Maryland, or
in fact in any of the others, care should be taken that animals
are not allowed to eat abundantly from thehulbs, especially under
conditions as described above. According to the observations
made in the present study in Maryland, the green parts of the
plants are eaten without injury by sheep, cattle and horses.
The snowdrop is perennial, the leaves, stems and flowers appearing in early summer and dying down within a few weeks
if hot weather is prevalent. The bulbs are small, white, appear:...
in,g much like those of the wild garlic (Allium vineale L.) but
are readily distinguishable by the lack of the garlic odor. They
set new bublets abundantly, spreading also by true seed, and
often are so thick in some fields that they form a carpet of
growth. The flowers appear at or near 'the top of the 6 inch stem,
are white, showy, with six distinct segments making a star-like
appearance. The leaves are narrow and grass-like, arising from
the bulb at the base of the stem. This plant has become a very
abundant weed in eastern Maryland fields.
Frequently found growin,g with the Star-of-Bethlehem on the
Eastern Shore, is the blue bottle or grape hyacinth (Musca1'i
1~acemosum (L.') Mill.). Reports have been received tlrat the
bulbs of these plants were also poisonous but no instances were
noted in which blue bottle bulbs occur in fields in which the
poisonings occurred, without also abundant growth of the Starof-Bethlehem. The possibility that they may be poisonous is not
excluded but as yet no conclusive evidence is at hand.
260
FIG. 7.
'l'HE MARYLAND AGRICULTURAL EXPERIlIIENT STATION
Cocklebur (Xanthium species). Seedling or cotyledon stage in
which the plants a?'e especially poisonous to hogs.
Cockelbur, Xanthium species
Young cocklebur plants have been responsible for poisoning
of pigs in a:t least six counties in the State. Also in an isolated
instance a horse and a pony were poisoned. The plants are found
as weeds throughout the State and the cases occurred in Baltimore, Carroll, Cecil, Harford, Queen Annes and Talbot Counties.
It is often true that poisonous plants are dangerous' only at
certain times or at certain sta,ges of their growth and this is
particularly true of the cockleburs. The plants cause poisoning
in the two-leaved or cotyledonary stage. The mature plant is not
known to be poisoning.
The poison in cockleburs is reported to be a glucoside, xanthostrumarin which is concentrated in the seeds. It apparently
passes into the seedlings upon germination.
The seedlings are often found growing abundantly in mud
flats along streams or in recently cultivated land and it is at
this time that shoats may eat enou,gh of them to cause severe
poisoning or even death. It has been reported that when pigs
are on milk feed they are not poisoned by the plants. A beneficial
treatment of poisoned animals is said to be the administration
of farts or oils by drench.
POISONOUS PLANTS OF MARYLAl'!D 1l'! HELA'l'ION '-1.'0 LIVESTOCK
261
White sweet clover, Melilotus alba Desr.,
Yellow sweet clover, Melilotus officinalis (L.) Lam.
A dozen separate cases in ten counties were recently recorded
in which cattle and horses were poisoned by eating damaged, or
spoiled sweet clover hay. It has been known for years that this
feed may produce injurious effects in animals. The continued
feeding of the hay may greatly cut down the clotting power of
the blood so that bleeding to death often results after severe
cuts or following an operation. For example in one instance in
Harford County four cattle died from excessive bleeding after
a dehornin,g operation. They had been on poorly-cured clover
hay previous to the operation.
Another symptom described as typical of this type of injury
is the appearance of small pockets of .blood which make puffy
swellings under the skin of the affected animals. These are said
to resemble the swellings accompanying "blackleg" injury burt
differ in the absence of a crackling sound when they are rUbbed.
Normally sweet clover hay, properly cured, and the plants
growing in the field are quite safe as a feed but the use of dam-
FIG. 8.
Flow6'1'ing b?'anch of C01n?non locust (Robinia PseudoAcacia).
262
THE MARYLAND AGRICULTURAL EXPERUIEN'r STATION
aged hay for more than a few days at one time is not safe. A
commonly recommended procedure for feeding damag~d hay is
its use only for a few days, perhaps a week, then feedmg other
hay such as alfalfa for a week or so before returning to the sweet
clover.
Black locust, Rohinia Pseudo-Acacia L.
This tree is known by its large compound leaves with two
stout spines at the base and oblong leaflets, its large clusters of
white, fragrant flowers followed by bean-like pods. There are
few farms or country roadsides which do not have at least a few
of these trees.
Sprouts and cuttings of black locust trees have been responsible for poisoning of animals in Maryland on at least three occasions. Two of these involved cattle and horses in Carroll County.
In Frederick County, a valuable mare was killed by the poison
in a quantity of trimmings which had been left in the pasture
and which the animal had freely eaten.
The locust tree contains a poisonous chemical substance of
the phytotoxin class, 1'obin, which has been recorded by various
investigators as being the cause of death not only of horses and
cattle, but of mules, sheep and even of humans. Among the
symptoms recorded for the action of this poison on animals are
stupor, depressed heart action and weakened pulse, and sometimes purging.
Black nightshade, Solanum nigrum L.
This plant, well known as being poisonous, has been found to
have caused poisoning' in Maryland on at least nine occasions.
In one case more than a dozen sheep were killed by grazing on a
large patch of the plants in Baltimore County. In another instance a number of hogs were made sick from eating the plants
and one of the animals died about tyenty-four hours after the
first symptoms of poisoning appeared. A few instances of poisoning of cattle and horses were recorded in the State.
Several years ago considerable loss was sustained when over
three hundred pullets died in rapid succession after eating from
a field overgrown with the black nightshade.
This. plant, and. some other ~emb.ers of the 1!ightshade family,
are saId to contam the narcotIc pOlson, solantne, which is toxic
or sometimes fatal to animals. Although it is true that the nightshade is frequently eaten without apparent injury, it is equally
true t~at animals have been poisoned by eating the plants and
for thIS reason should be kept from eating abnormal quantities.
at anyone time.
POISONOUS PLANTS OF :MARYLAND IN RELATION TO LIVESTOCK
FIG. 9.
FIG. 10.
263
Blacle nightshade (Solanum nigrum).
Bitter·,qweet (Solanum Dulcamera) , sometimes called matrimony vine in Mar·yland.
264
FIG. 11.
'fHE lIIARYL_-\ND AGRIC'UL'l'URAL EXPERIMENT S'l'ATION
H orsenettle (Solanum ca1'olinense) , Both the leaves and
stems are spiny. The be1"ries are precedecl by white or
purplish flowers.
Symptoms of poisoning include sta,ggering and loss of coordination, digestive disturbances such as diarrhoea and vomiting,
and paralysis.
The black nightshade is found growing in woodlands and especially in waste places around fa.rm buildings throughout the
State_ It is an annual, has clusters of small, white, five-parted
flowers followed by black berries. The WOllderberry, similar to
POISONOUS PLANTS OF MARYLAND IN RELA"'l'ION TO LIVESTOCK
265
the black nightshade but with larger berries, should perhaps be
kept from farm animals as carefully as the nightshade.
The horse nettle, Solanum carolinense L., is found abundantly
in pastures but is seldom eaten. The bitterswe~t, Solanum Du:lcam61'a L'J is an ornamental vine occasionally grown around the
home, or rarely wild. These and other plants of the nightshade
family, a're potential sources of poisoning.
Tobacco, Nicotiana tabacum L.
On a farm in Anne Arundel County in August, 1936, two
horses died under "mysterious circums1tances." They had been
on apparently good pasture and had been kept in a shed overnight. On being led out the next morning it appeared that they
were quite weak, arose with difficulty, exhibited nervousness
and seemed to be unable to see where they were going. They had
to be directed to the pasture where both animals died within
forty-ei,ght hours. A surprisingly similar case of apparent poisoning and death had occurred on this same farm, in the same pasture and at the same time of the year about six years previous
to the present instance.
The poisonings occurred during the tobacco harvest and it
was found that the animals had eaten from some discarded
leaves and stalks left in the shed in which they had been kept
overnight. The symptoms of poisoning described here resemble
those produced in animals used in some feeding trials conduded
by the United States D.epartment of Agricmlture. In these, wild
tobaccos were fed to the animals under controlled conditions and
the following symptoms among others, were described: "muscular weakness, rapid weak pulse and contraction of the eye
muscles." The latter symptom or effect may account for the
apparent dimness of vision observed in the Maryland cases. It
is also of interest that the poison was said to take effect soon
after the plants were eaten by the expeTimental animals, as was
the case also in Maryland.
Tobacco contains the well-known alkalOid, nicotine, which is
a narcotic poison. Steyn recommends tannin as an antidote for
poisoning as it forms with the nicotine the relatively non-toxic
nicotine-tannCLte.
Jimsonweed or thornapple, Datura Stramonium L.
This common plant, formerly called Jamestown weed, is found
abundantly in the State as a farm weed. It can be recognized
by its coarse growth, rank foliage, large trumpet-shaped white
or purple flowers and the spine-covered pods filled, when they are
mature, with small black seeds. It is a member of the nightshade
family and like certain other members of this group contains
toxic principles. In this case the toxic principle is thought to be
an alkaloid, hyoscYCLmine.
266
'l'HE lIIARYI,AND AGRICULTURAL EXPERUIENT STA'£ION
It may occasionally be eaten by stock and may result in poisoning of the animals. In a number of cases, hogs and cattle were
found to have been poisoned by the plants and in one case there
was poisoning of a horse. In addition, several chickens were
killed from the effects of eating quantities of the seeds. The foregoing instances occurred in six counties, Baltimore, Carroll,
Frederick, Harfol,d, Kent and Queen Annes. It is of interest that
a report from Alabama states that mules have been fatally
poisoned there from ea:ting jimson weed plants. The poison is
said to be especially toxic to hogs.
Among the symptoms exhibited by poisoned animals are
nausea, dilated pupils, heavy breathing, loss of sight and often
loss of voluntary motion. No specific can be suggested but elimination of the plants is practical as they are annuals and can be
removed by cutting before fruit is set, several years in succession.
FIG. 12,
Mat1'imony - 'Vine
(Lycittm halimifolium) ,
Kentucky coffee tree, Gymnocladus dioica (L.) Koch.
The Kentucky coffee-tree, sometimes called "mahogany" in
Maryland, is found in scattered locations throughout the State
It ,is, usually found as a shade tree around homes or far~
bmldmgs.
POISONOUS PLANTS OF MARYLAND IN RELATION TO LIVESTOCK
FIG. 13.
267
Pod and branches of Kentucky coffee tree (GymnocZadus
dioica) .
In one instance in Harford County, eleven sheep died after
eating cuttings removed from a large tree. The animals died
within twenty-four hours of the first indications of the poisoning.
Controlled feeding experiments reported by Marsh and Clawson of the United States Department of Agriculture have shown
that seeds of the Kentucky coffee-tree are quite poisonous to
cattle. Among the symptoms observed in the poisoned animals
were congestion of the lungs and in the fourth stomach. Reports
from the Indiana Agricultural Experiment Station have reported
deaths of sheep which have eaten the foliage of the tree.
268
THE )LtRYLAXD AGRICULTUUAL EXPERIMENT STATION
It is obvious from the information here that it is dangerous
to allow farm animals access to the leaves of the mahogany
tree and certainly cuttings should be kept from their reach.
Buttercups, blister crowfoot, Ranunculus sceleratus L.; tall
huttercup, Ranunculus acris L.; small-flowered buttercup,
Ranunculus ahortivus L.; bulb buttercup,
Ranunculus bulbosus L.
In Garrett and Carroll Counties it was found that cattle had
been poisoned after eating "meadow grass" which had a high
proportion of buttercups in it. The plants are well known to
produce scours in cattle and in these cases had that effect.
FIG. 14. Blister c?'owfoot (Ranunculus scelemtus).
POISONOUS PLANTS OF MARYLAND IN RELA'rION TO LIVESTOCK
269
Milk produced by cattle eating heavily of buttercups is said to
be bitter and often of a reddish color.
The cursed crowfoot contains anemenol, a very acrid substance which may cause extreme irritation of the digestive tract
of cattle which eat the plants. Although the plants are known
to cause trouble in fresh hay, it is said that in thoroughly dried
hay they are harmless as the toxicity is lost as the plants dry.
Buttercups are found throughout the state in woodlands, open
clearings and meadows, often becoming very abundant in moist
land and along stream banks. If trouble with the plants is
experienced it is well to fence off the most severely infested
sections or attempt to eliminate the plants by hoeing.
Common milkweed, Asclepias syriaca L.
During a very dry season in 1937 a dozen sheep died after
eating plentifully from a growth of the common milkweed.
These plants were practically the only available vegetation
FIG. 15.
Common milkweed (Asclepias syriaca).
270
THE MAHYLAND AGRICUL'l'URAL EXPERIMENT STATION
which had not dried up during the drought. Though seldom
eaten, these plants are a potential source of trouble with livestock.
The common milkweed is found in pastures and waste places
throughout the State and is well known for its white, milky
juice which exudes whenever the leaves or stems are broken.
The toxic principle in the plant is not well known except that
it is resinous in nature and is quite toxic to animals.
Several species of the milkweed family are known to be
poisonous. The chief trouble with the plants has been experienced in western states where numerous instances of poisoning
of sheep have been recorded. The swamp milkweek, Asclepias
inca,7'nata L., found in Maryland, has been reported as having
caused poisoning of sheep in Indiana. The whorled milkweed,
AsclepiCLs verticilla,ta L., found only rarely in the State, is a
well known deadly poisonous plant in other sections of the
country.
Horse-chestnut, Aesculus Hippocastanum L.
The leaves of this tree were found to have poisoned cattle in
one instance in Carroll County and the dried fruit and leaves
killed several cattle in Baltimore County.
The horse-chestnut is found in scattered locations throughout
the State as a shade tree in cities and villa,ges. It has large
clusters of whitish flowers spotted with purple or yellow and
the fruit is a 1 to 3-seeded leathery round pod covered with
short spines when immature, with seeds over an inch thick.
The large leaves are opposite on the stems and usually have
seven divisions or leaflets.
The poison present is reported to be a glucoside, aesculin, and
is reported to cause inflammation of the mucous membranes,
vomiting, stupor and incoordination of actions when eaten by
live-stock. The young leaves and the flowers are said to be
especially toxic to cattle and may cause severe poisoning, although deaths from this cause are apparently rare.
Relatives of the horse-chestnut which may on occasions be
found in the State and which also should be kept from farm
animals are the Ohio buckeye Aesculus glabm Willd., and the red
buckeye Aesculus pavia L., the sweet buckeye, Aesculus octandra
Marsh., and Aesculu.s pa1'vijlora Walt., bottlebrush, or dwarf
buckeye.
Castor-'bean, Ricinus communis L.
Although rarely eaten, this plant has been known to cause
poisoning of cattle, horses and sheep in Maryland. In one case
several hogs died after eating some of the castor-beans. In addi-
POISONOUS PLANTS OF lIIARYLAND IN RELATION TO LIVESTOCK
271
tion, a few instances were found in which people had been made
severely ill by chewing- a few of the beans.
The castor-bean contains, besides the well known castor oil,
a very severe poison of the phtotoxin class, ricin, or said by
some to be ricinolein. This poison, when introduced into the
system of an animal causes coag-ulation of the blood and usually
death.
The plants are g-rown as ornamentals in scattered locations
in Maryland. They are characterized by their large leaves, vigorous growth and black, white or mottled and colored seeds
which are enclosed in spiny pods.
Bracken, pteridium latiusculum (Desv.) Hieron.
This common fern is rarely eaten by animals but on occasions
in Garrett and Queen Annes Counties, poisoning of cattle has
occurred from the effects of consuming quantities of the plants.
On one occasion in Garrett County it had been an exceedingly
dry season and the only available forage was the bracken. This
formed a large proportion of the plants found in the pasture at
the time. The cattle were made extremely sick. They became
weak, milk production stopped, and all showed the same attitude,
having their heads hung down and all showed bleeding from
the mouth and nostrils. Seven cattle died within four days
following this particular instance of poisoning-.
The conditions of poisoning- and the symptoms described here
are practically identical with those produced experimentally in
feeding bracken to cattle at the New York State Veterinary
Colleg-e at Cornell University. Additional characteristics of the
trouble as reported in that work are that the poison is apparently cumUlative, and that the animals have a high temperature.
The poisonous principle has not as yet been isolated and
described.
The bracken is found in light soils throughout Maryland, is
often quite abundant in mountain pastures and in burned-over
pineland. As it is thought to be a potential source of danger,
it should be removed by repeated cuttings, two or three times
a year.
Oak, Quercus species
In an isolated instance in CauoH County several cattle died
after eating quantities of oak sprouts. Although it is a common
observation that animals will graze on oak leaves and sprouts
without injury, an occasion such as the above shows that
exclusive feeding- on them may be dangerous.
272
THB lIIAllYL.-\ND AGRICULTURAL EXPERIMEN'l' ST.\TION
FIG. 16.
Bracken (Pte?'idium latiusculum).
POISONOUS PLANTS OF MARYLAND IN REL<\ 'l'ION TO LIVESTOCK
273
Reports from some western states indicate that occasional
trouble is experienced with poisoning of this nature. There, if
the animals are allowed to graze on oaks for extended periods
in areas devoid of other vegetation, a general run~down condition, especially in cattle may follow. The poisoning is evidenced
also by severe irritation of the digestive tract resulting in the
appearance of feces with variable amounts of blood and mucus.
In areas in which oaks have been a ~ubstantial part of the available forage, it has been suggested that feeding of concentrates
or alfalfa hay may prevent serious injury from the oak poisoning.
Privet, Ligustrum Oivalifolium Hassk.
A number of sheep were killed by eating a quantity of trimmings from a privet hedge. Although this is apparently a very
rare occurrence, live-stock should not be allowed to have access
to these plants as forage.
It is of interest that a small boy in the State received a rather
severe case of skin-poisoning from working with a privet hedge.
In addition, reports from Europe state that chHdren have been
poisoned by eating' the berries of the plant.
The above name applies to the most generally grown California privet, but several other species of privet are cultivated in
Maryland.
Alsike clover, Trifolium hybridum L.
This legume is quite common in the state and normally not
injurious. It is included here since it has been frequently mentioned as a source of bloat in sheep. In addition this plant is a
generally known source of skin-poisoning of animals by photosensitization. (See later pages for further discussion of this
topic.)
Reports of poisoning of sheep in Queen Annes County have
been recorded.
Box, Buxus sempervirens L.
In an isolated case several sheep died after eating quantities
of leaves and branches trimmed from a box hedge in Queen
Annes Oounty. The plants are commonly grown as ornamental
shrubs in the State. The box has been known as a poisonous plant for some time and is said to contain several toxic
alkaloids, among them being buxine which is a severe emetic or
purgative.
274
FIG. 17.
THE MARYLAND AGRICULTURAL EXPERIlIlENT STA'fION
Loblolly pine, old field pine, (Pinus taeda). The needles are
usually in bundles of th?'ees and longer than in other Maryland pines.
Loblolly pine, Pinus Taeda
In Talbot County in one isolated instance, cattle died after
eating quantities of pine straw included in the bedding used for
the animals. Pine needles are of course normally avoided as
forage by stock but the above instance indicates that they are
potential sources of poisoning. They should not be used in bedding or where they are likely to be eaten in preference to other
feeds.
POISONOUS PLANTS OF lIlARYLAND IN RELATION TO LIVESTOCK
FIG. 18.
False hellebore
(Veratn~m
275
viride).
False hellebore, Veratrum viride Ait.
Although this plant is rarely eaten because of its bitter taste,
in a few cases cattle were poisoned after eating the plant in
pastures in Garrett County. Reports from other states also
indicate that false hellebore may at times poison cattle and
sheep.
The false hellebore is a member of the Lily family, is perennial, grows in marshy land, on streambanks or in moist woodland in the western parts of the State and in scattered locations
in other parts. The plants have greenish-yellow flowers jn a
pyramid-shaped cluster at the top of the 2 to 8 foot stalk. The
plaited leaves along the stem are over 6 inches long and 3 to 6
inches wide.
It is said to contain several poisonous alkaloids and has its
chief effect on the muscles of the poisoned animal. Symptoms
accompanying poisoning include salivation, muscular tremors,
low temperature, and death resulting from paralysis of the
heart.
276
'l'IiB 1IARYLAND AGRICULTURAL EXPEHIMENT S'l'ATION
STOCK-POISONING BY PRUSSIC ACID PRODUCED
IN PLANTS
A considerable numbel' of cases of poisoning of animals by
prussic acid (also called hydrocyanic acjd or HeN) have been
found. Several plants have been respo;nsIble for these cas~s and
each is discussed under separate headmgs. The g-eneral CIrcumstances and method of poisoning are similar for the various
plants and this will be described here.
A number of plants contain the chemical substances known
as glucosides. Some of these may be of the type classed as
cyanogenetic, or capable of producing hydrocyanic acid, following certain chemical changes which may occur in the pla~t.
The changes involved are generally as follows; the glucosIde III
the plant tissues is acted upon, in the presence of water, by
an emulsin-type enzyme which causes the liberation of free
hydrocyanic acid along with other products. The HeN, if
liberated in the plant just previous to being eaten by a grazing
animal, may be in sufficient concentration to cause poisoning and
eventual death of the animal. It is also possible that the liberation of the acid from the glucoside may not take place until
the plants are within the digestive system of the animal.
Among the conditions which have been described as especially
favorable for the production of prussic acid in plant tissues are
the following; plants injured by trampling, frost injury, wilting,
stunting by drought, insect injury, and in addition, vigorously
growing first or second growth plants (of sorghum, for example) or vigorously growing sprouts (of wild black cherries).
It is probably true that the acid is produced at times under
all of these circumstances although no reliable method of predicting' the times of high concentration has been described.
Prussic acid which has developed in plants cut for hay will gradually disappear in the drying of the hay and cyanogenetic
glucosides are apparently destroyed in ensilage.
Animal!,! affected by the poison in Maryland include cattle,
horses, mules, hogs, and sheep. In addition one instance of
poisoning' of chickens was encountered.
Symptoms of poisoning have been described by numerous
investigators. Some of the most characteristic symptoms are
the extremely rapid action of the poison which may without
warning bring about the death of animals within the short
period of from a half hour or much less to three or four hours,
and second, perhaps, in importance is the difficult breathing
exhibited by poisoned animals. The actions suggest that the
poisoned animal is being strangled to death, this resulting from
the fact that the blood can not perform its normal functions
POISONOUS PLAN'l'S m' MARYLAND IN RELATION TO L.IVESTOCK
277
of oxygen exchanges and paralysis of the lungs follows. Death
is by asphyxiation.
Other symptoms which should be included as typical of
prussic acid poisoning are a short period of stimUlation followed
by more subdued appearance, slow pulse, dilated pupils, spasms,
staggering and loss of consciousness before death. The heart
may beat for a time following cessation of breathing. Those
cases in which treatments may arrive in time are probably less
frequent than the others as the poisoning is often too quickly
effective for help to arrive.
Treatments for animals poisoned by pl'ussic acid.
In the event a veterinarian cannot be reached for treatment
of poisoned animals, some frequently suggested remedies are
the oral administration of corn syrup, glucose, or diluted molasses. Another frequently suggested remedy is the intravenous
injection of methylene blue.
There have been several reports from veterinarians in various
sections of the State that the most effective treatment for
cyanosis is the rather recently developed remedy of injection,
intravenously or intraperitoneally, of sodium nitrite and sodium
thiosulfate. The dosage as given by the United States Department of Agriculture, Bureau of Animal Industry is as follows:
for cattle-2'0-HO cc of a 10 % aqueous solution of sodium
nitrite.
and
100.1200 cc of a 10% aqueous solution of sodium
thiosulfate.
for sheep-l0 cc of the sodium nitrite solution
and
30 cc of the sodium thiosulfate solution
The follOWing plants found in Maryland may cause poisoning
of animals through the development of prussic acid: Flax, *wild
black 'cherry, wild red ,cherry, choke cherry, *peach (kernels),
plum and cherry seeds, apple (seeds), *sorghum, (and varieties),
"'Johnson grass, "'lima bean (vines), arrow grass, and manna
grass.
The 'I' indicates those plants which have caused actual cases
of poisoning of live-stock in Maryland. They are discussed more
fully on the following pages.
Apple seeds are mentioned, not as having caused stock-poisoning, but because of the fact that one instance w~s recorded
from personal inquiry in which an adult man was kIlled following eating a cup of these seeds at one time. The seeds had been
saved up, apparently thought to be a delicacy in small amounts,
278
THE MARYLAND AGRICULTURAl, EXPERIMENT S'l'ATION
and upon being eaten developed enough of the deadly prussic
acid to cause this tragic death, The instance is recorded here
as a caution to others who might attempt to eat mOre than a
few of these seeds at anyone time. Previous investigators
have reported that apple seeds contain appreciable amounts of
a,nwgda.lin, from which prussic acid is developed, but actual
reports of poisoning are rare.
Arrow grass, T?'igloC'hin striata. R. & p" is found occasionally
in marshy sections of the Eastern Shore and is a potential source
of prussic acid, although the plants are probably seldom eaten.
FIG. 19.
Bark and leaves of wild blcLCk cherry (PrunuB serotina) ,
Black cherry, Prunus serotina Ehrh.
, Perhaps, the most w~dely know cause of plant poisoning of
!lVe-stock 111 the State IS that from the wild black cherry. It is
1U tl~e sh?ot,s and l~aves of this tree that prussic acid or hydrocyamc aCId IS occaslOnally formed in dangerous amounts. In this
survey alone, some twenty separate instances of poisoning in~
POISONOUS PLANTS OF :MARYLAND IN RELATION 'l'0 LIVE:,oTOCK
279
volving death or serious injury of over seventy-five animals were
recorded. These cases occurred in seventeen of the twenty-three
counties in Maryland and cattle, horses, sheep and in one instance chickens have been poisoned.
Although it is frequently said that poisoning is more likely to
occur when leaves of the tree are wilted following frosts or
trimming, it was found that vigorously growing spmuts were
just as dan,gerous a source of injury. In Dorchester County, for
example, two heifers and two mature cows met sudden death
after browsing on the sprouts. growing from a wild black cherry
stump. On another occasion, in Baltimore County, -two calves.
died soon after eating cuttings from a wild cherry fence row.
A more severe or costly instance was recorded jn Somerset
County where on one occasion five cattle died after eating from
the outtings removed from a row of ,the wild cherry.
The trees are quite commonly found in farm yards and along
fences throughout the State and although under normal circumstances may be the cause of no trouble for years at a time, it
should be remembered that 'they are potential sources of poisoning. Among the practices which have caused the most trouble and
those which should be avoided are throwing cuttings of the trees
to stock, allowing broken branches to remain in the pasture and
leaving the wild cherry stumps to sprout up after being cut.
Peach (especially ke;rnels), Pl'unus Persica (L.) Batsch.
A number of hogs died on a farm in Carroll County after eating a quantity of peach seeds thrown from the kitchen and a
similar instance occurred in Charles County. The seeds are
known to be potential sources of hydrocyanic acid as they contain the chemical, amygdalin, which may be broken up into substances including the deadly acid. The hogs died quite suddenly
in each instance, as is typical of the poisoning produced by the
hydrocyanic acid.
Sorghum, Sorghum vulgare Pers.
This well-known field crop plant may at times develop enough
prussic acid to be dangerous to animals. The poison, which is
developed from the glucoside, dhurrin, is often formed when the
plants are frosted or when the second growth is growing most
rapidly. It is said that the plants are least dangerous after coming into head.
Instances of poisonin,g were recorded from Baltimore, Carroll,
Frederick, Queen Annes and Washington Counties and in these
cases cattle were poisoned most frequently although one case of
the death of a horse was included.
The suggestion has been made by several investigators that
in the event of doubt as to the poisonous nature of a field of
280
'rIm ~nRYLAND AmnCULTURAL ExpmU1;mN'r STA1'lON
sorghum at anyone time, animals should be kept off or if allowed
to graze, should be fed concentrate~, as sug~rs te_nd to decrease
the amount of free HCN liberated III the al1lmal 111 the event of
the production of the poison.
Johnson grass, Sorghum halepense (L.) Pel's.
This vigorous grass, often becomin,g a 'troublesome weed but
not found extensively in Maryland, was responsible for the death
of a horse in an isolated case of poisoning which occurred in
Frederick County. The plant may develop dangerous quantities
of prussic acid under conditions favorable for its production.
The sorghums include several other types than those discussed
here such as Sudan grass, kafir, feterita and milo and perhaps
all should be treated as possible sources of prussic acid poisoning.
Lima bean or butter bean (vines), Phaseolus Iunatus L.
The vines and pods of the lima bean plants caused one of the
most unusual types of poisoning encountered in the present investigations. On at least four separate instances on the Eastern
Shore, in Queen Annes, Talbot, and Worcester Counties cattle
have been poisoned from eating the pods and vines of these common ,garden plants. In each instance the animals were stricken
,'e1'Y suddenly and in the fatal cases death followed within a few
hours of the first indication of poisoning. These cir0umstances
are typical of those accolllpallying' prussic acid poisoning and
the cases were in fact so diagnosed by the attending veterinarians.
On one occasion in which the veterinarian was able to anive
in time, foul' cattle were stricken and were in a comatose condition. Prompt treatment for prussic acid poisoning brought all
foul' animals hack to normal within a short period of time.
Two other instances, on the other hand, terminated fatally
for the poisoned cattle. One of these instances occurred in Talbot
County and here the cattle had eaten vines which had been partially killed back by a frost only a few hours before the poisoning. The other case, in Worcester County, involved rbhree animals
dying shortly thereafter.
Certain varieties or relatives of the lima bean, especially the
highly colored types such as the Burma beans, have been reported
by investi,gators in England, South Africa and I:Qdia to contain
appreciable amounts of the glucoside, phas,eoluJncttin. It is from
this that prussic acid may be developed in the plant. It has also
often been reported that small amounts of the acid-forming substances are to be found in the common lima beans. Reports of
actual poisoning of animals and even of 'humans have been made
POISONOUS PLANTS OF :lIIARYLAND IN RELATION TO LIYESTOOK
281
by the investigators mentioned above, and in each it was the
bean (or seed) itself which was the source of the trouble. The
instances of poisoning of cattle by the lima bean vines in the
three Maryland counties cited are, as far as it has been possible
to determine, unique in poison plant literature. The well known
scent of prussic acid has been readily detected on other occasions
in piles of frosted 'lima bean vines in the State.
The above information should serve to warn against allowing
animals to ,gTaze on the lima bean plants, especially late in the
fall or at time of frost.
Eastern mannagrass, Glyceria septentrionalis Ritche.
Fowl manna grass, Glyceria striata (Lam.) Ritehe.
These grasses are usually found in very wet land or in shallow
running water. It is known that some of them may contain substances which are potential sources of prussic acid. That the
plants are capable of producing prussic acid in Maryland was
indicated on several occasions. During the course of the present
investigations, a large hunch of fowl mannagrass was collected
from a patch growing in running water of a small stream in
Garrett County. This ,grass was wrapped, wet in a newspaper
and placed on the floor of a closed car. Upon return to the car
in about two hours, it was found that there was a very strong
odor of prussic acid which had developed and the car had to be
aired oU't before being entered. It happened that some test strips
of paper, moistened with sodium picrate, which were prepared
for testing qualitatively for the presence of prussic acid, were in
the car at this time and all showed a very positive reaction.
Glyceria septcn(l'ionalis Hitchc., had not (in 1938) been reported as being capable of producing prussic acid. A sample collected in Anne Arundel County, Maryland, in that year was
tested qualitatively by the sodium picrate paper test and found
to exhibit a strong positive reaction. Samples of this same lot
were submitted to Dr. J. F. Couch of the United States Department of Agriculture, a specialist in the chemistry of stockpoisoning plants, who reported that quantitative tests showed
the grass to be a very potel'lt source of prussic acid.
In case poisoning resembling cyanosis has occurred where
wild black cherry or other common offenders are not present, it
may be well to consider these grasses. In Baltimore County a
recent series of losses of calves from some rapidly-acting poison
has led to 'the belief that manna grasses were the source of the
injury. In the pasture where these deaths occurred was a low
wet section including abundant growths of the fowl manna grass
which had been gra:zed by the animals.
282
2'HE MARYLAND _-I.GRIOULTVRAL EXPERHIENT STATION
Flax~ Linum usitatissimum L.
The common cultivated flax plant contains a cyanogenetic glucoside, phaseolunatin, which may c.ause th: .plant to. be t~xic or
even fatal to animals under certam condItIons. It IS sald also
that occasional instances have been recorded in which "linseed
cake" feed has proved toxic to cattle and pigs.
Linum. vi'~'[linianum L., the woodland flax, and L. ntedium
(Planch) Tre1., the stiff yellow flax, are found wild in Maryland although it is not known that they are likely to be poisonous
or even eaten.
POISONING OF LIVE-8TOCI( BY FUNGI
Although the principle emphasis in the present study is on
flowering plants it has been found necessary to discuss a few
conditions of poisoning by fungi. It may be said that no stockpoisoning from the effects of "toadstools" or fleshy fungi, was
encountered. Two of the most poisonous of this type of fungus
are the fly amanita, Amanita m.uscaria (L.) Pers. and the deathcup fungus, Am,anita phalloides Fr., which are both found in
Maryland.
Inquiries as to the cause of the ,greatest total loss of live-stock
due to any types of poisoning, sent to veterinarians practicing
in Maryland, revealed that moldy corn was the cause most frequently mentioned.
In one ins,tance a stock owner reported the loss of a mule
under circumstances which led him to. suspect moldy corn which
the animal had been eating. The loss occurred while the mule
was working in the field. It suddenly stopped, fell to the ground,
struggled considerably, attempted unsuccessfully to rise and died
within a few hours. A second mule which had eaten from the
same moldy corn had also, been S1tricken but recovered after a
prolonged period in which it had been una:ble 'to eat or drink; its
throat apparently paralyzed.
It is not known at the present time the exact nature or cause
of poisoning by moldy feed, whether it is due to toxic slibstances
formed in the fungi 'themselves Or to products formed in the
,grain through actions of the fungous growth.
.
Experiments at the Iowa Agricultural Experiment Station indicated that prolonged feeding of moldy corn to horses actually
produced poisoning and death of some of the animals. In feeding- trials conducted in South Africn it was found that cattle
fed on c?rn infected wi~h.the fungus Diplodia zea~ (Schw.) Lev.
wer.e p~Isoned and exhIbIted nervous sYIll;ptoms mcluding incoordmatIOn of movements and later paralysIs. Other feeding trials
similar in nature to the above have been conducted at various
Experiment Stations without any indication of poisoning of the
POISONOUS PLANTS OF MARYLAND IN RELATION
'ro LIVESTOCK
283
experimental animals. It is true, however, that there have been
numerous instances of poisoning and death of live-stock in
Maryland from the effects of moldy corn and for this reason its
use as feed should be avoided if possible.
Not only moldy corn but moldy oats, ensila,ge and hay of various types have also been reported as having caused poisoning of
live-stock in the State.
Poisoning by Ergot
Ergot on wild grasses, wheat, rye, oats and barley is found
occasionally in Maryland fields, especially in warm, damp seasons. On a few occasions consumption of the ergotized grain has
caused poisoning of stock. The growth which develops within
the grain is a parasitic fungus, Claviceps purpurea (Fr.) Tul.
(and perhaps other species), and its growth destroys the normal
tissue in the grain, replacin.g it with dark colored material. The
fungus produces in place of the grain an elongate, slightly
curved, dark colored body which is much larger than the unin~
fected grains.
.
The fungus in this condition, as it may be when infected hay
is fed to animals, contains toxic substances. These include ergotoxine, which is a cumulative poison that may severely affect
cattle, horses and other anima:ls.
There are two distinct types Of poisoning produced in animals
poisoned by ergot. In one the nervous system is affected, resulting in depression and fatigue, a run-down eondition, paralysis
in the limbs or in the tongue and muscles of the throat and in
some cases convulsions. The smooth muscles of the animal may
be affected and a ~eI1-known effect of ergot poisoning, abortion,
may be produced. Another train of symptoms involves the muscles of the small blood vessels which may contract, thus impairing the circulation, especially in the extremities. The tissues of
. the legs, the hoofs, tongue, ears, tail or other parts of the body
may be severely injured with gangrene setting in and often loss
of tissues or even death of the animal results from the poisoning. Treatment of poisoned animals is sometimes made by the
administration of tannin as a drench.
Poisoning of live-stock by ergot on Paspalum grass
Several cases of poisoning of horses in Maryland have been
attributed to the effects of the fungus, Claviceps p,aspali Stephens and Hall, which replaces the seed of species of Pa.spal:um,
especially Paspalum laeve Michx. in Maryland.
Recently in Dorchester County a horse died after exhibiting
distinct symptoms of poisoning, including pronounced trembling
a day or so before death. It was found that the hay on which
284
'nm )[ARYL.UD _lORICUL'l'URAI, EXl'lCRDIEX'l' S'l'A'rION
the horse had been feeding contained a considerable quantity of
Pc(;Spa.lu:/n lcreve which was very heavily infested with ergot. The
hay was several months old. Several years ago cattle that had
died on paspalum ergot infested pastures were found on postmortem to contain thousands of the round flat paspalum seeds.
That the ergot is poisonous has been shown by the Mississippi
Agricultural Experiment Station in controlled feeding trials.
The sclerotia or overwintering bodies of the fungus, were quite
toxic to cattl~ and the poison was found to be cumulative in its
effect and to produce nervousness and trembling. The poison
was reported to be an amorphous alkaloid. It is also of interest
that similar feeding trials of the paspalum ergot in South Africa
showed that the fungus produced clearly distinguished cases of
poisoning in cattle, with symptoms including incoordination of
movements, muscular tremors and accelerated, weak pulse.
It is a valuable preventive measure to make periodic checks
of pasture condition with respect to the presence of these growths
on the paspalum grasses and to prevent animals from grazing
on the infected plants if they are found.
"PHOTOSENSITIZATION" OR POISONING OF ANIMALS BY
PLANT SUBSTANCES ACTIVATED BY SUNLIGHT
One of the peculiar relations between the activities of plants
mid animals is the action called "photosensitization." This may
be described as follows: when certain plants are eaten by animals there is absol>bed by the digestive system of the animal a
plant product, perhaps a fluorescent substance, which is spread
throughout the animal's skin, or in the tissues just under the
skin. In the portions of the skin which are unpigmented (white)
the rays of the sun bril\g about an activation of the substance,
causing irritation, inflammation, swelling and blisters. In the
pigmented areas of the skin, none of this effect is apparent and
it is thought that the active wave-lengths of light are perhaps
screened out by the pigments present. A white skinned animal,
having eaten the plants of this type. does not develop the skin
poisoning unless subjected to the direct rays of the sun and
dark-skinned animals do not get the effect under any circumstances.
In the present study in Maryland there were encountered no
authenticated cases of photosensitization although a number of
cases of skin poisoning reported strikingly resemble that produced by. photodynami.c plan~s. The following list of plants,
both cultlVated and wIld, whIch are found in Maryland have
been reported. from various sources to cause poisoning in the
manner deSCribed above. If any of these are eaten as a major
POISONOUS PLANTS OF MARYLAND IN RELA'rrON TO LIVl's'rOCK
285
portion of the feed for a prolonged period, it is possible that
the animal may develop symptoms of this poisoning:
St. Johnsworts: Hypericum perforatum L. common St. Johnswort, H. mutilum L. dwarf St. Johnswort, H. pllnctatum Lam.
spotted St. Johnswort, H. densiflorum Pursh. bushy St. Johns.wort, H. canadense L. Canadian St. Johnswort.
The St. Johnsworts are perhaps the best known causes of
photosensitization. One report of poisoning of cattle from eating these plants was received but it was not reported that the
symptoms resembled those of the skin-poisoning type. The
plants listed here are found scattered throughout the State
and are sometimes found in dense stands. They are known by
their shrubby appearance, dotted leaves which are in pairs and
opposite on the stems, and the showy five-parted yellow flowers.
Buckwheat, Fagopyrum esculentum Moench.
The toxic substances are said to be present in all parts of the
plant and this type of poisoning by buckwheat is called "fagopyrism."
Rape, BrassicCL NCLPUS L. is another cultivated plant said to
be photodynamic.
Alsike clover, Trifolium hybridum L.
This common legume is reported to be especially toxic to
sheep in producing the skin poisoning.
Knotweeds and smartweeds. Polygonum pennsylvanicum L.,
knotweed; P. hydropiperoides Michx., mild water pepper; P.
punctatum Ell., water smartweed; P. aviculare L., knotgTass; P. erectum L.; P. Persicaria L.; ladys-thumb.
These plants are found in many sections of the state and although probably rarely eaten because of their acrid juices, are
potential sources of trouble as producers of the substances
responsible for photosensitization, described above.
POSiSIBLE STOCK-POISONING BY POTASSIUM NITRATE
IN PLANTS
One of the most recent developments in the study of poisoning
of animals by l)lants is the discovery by worker~ at the Wyoming Agricultural Experiment Station that serlOUS losses of
cattle have been caused from the effects of eating oat hay which
contains high proportions of nitrates. Similar reports have
286
THE J\lARYLAND AGRICUUrUHAL EXl'ERI1IENT STATION
come from Colorado and Nebraska and it was suggested that,
wheat, barley, sorghums and other crops may possi.bly prod~lce
the same effects at times. In the instances recorded m Wyommg
it has been almost invariably true that the hay has been wet
by snow or rain just previous to the poisoning and that the
attacks have been sudden. They were accompanied, in cases
involving cattle, by difficult breathing, convulsions and usually
death. It was said also that the blood of the poisoned animals
turned a very dark color.
The explanation given for these occurrences was given in the
fact that potassium nitmtes are converted into nitrites. The latter act upon the hemoglobin of the blood changing it to methemoglobin which is incapable of carrying on the normal functions
required in oxygen exchanges. The animal dies by asphyxiation,
much as in poisonings by prussic acid, described on previous
pages.
No instances of poisoning of live-stock from oat hay were
discovered in this investigation but it is of interest that one
report was received from a locality in the State in which sudden
death of cattle followed their eating from a pile of wheat straw
soon after a frost. Unfortunately it was impossible at the time
to further investigate this occurrence but is is thought worthy
of note as a precaution for prevention of other such cases.
It seems probable, however, that nitrates may have been
responsible for certain other isolated instances of poisoning in
Maryland. (The possibility that these were due to prussic acid
formation is not excluded but other causes seem more likely.
The effects of the nitrites and of HeN are apparently similar.)
On one of these occasions, in Caroline County, several horses
were poisoned following ~consumption of a quantity of sweet
corn in a field. A mule- eating from the same lot was also made
sick. One of the horses which had become suddenly ill had
fallen repeatedly, was nervous and touchy and had at first a
rapid pulse. The animal became weaker, finally fell and died in
convulsions. A veterinarian attending reported that the symptoms resembled those of prussic acid poisoning although the
characteristic odor of HeN was absent.
On another occasion in Cecil County, several cattle were
stricken after eating from a pile of newly husked earn. The
suddenness of the deaths also suggested a rapidly acting
poison. The following description (received by correspondence)
was made of this occurrence of poisoning; "I had one herd that
had broken into a field of corn in the night and eaten out of
piles of husked corn. I saw them within an hour after the
owner found them and five out of the twenty were in a comatose
.l:'UlI:lONOUS PLANTS OF MARYLAND IN RELA'l'lON TO LIVEs'rOCK
287
condition, in fact I thought all five were dead. Treated three of
the five intravenously with sodium thiosulfate and sodium
nitrite, the three recovered in about half an hour, the other two
died before I got them inj ected. None of the other animals
showed any symptoms of poisoning or anything abnormal but
all were given a quart of linseed oil. The quick recovery after
injection makes me wonder if there was not sufficient HGN in
the new corn to have caused HeN (prussic acid) poisoning
even though it was good corn. The five animals that were sick,
out of the twenty in the field, were about two years old, the
others were mature cows."
(signed) James S. Hogg, D. V. M.
In addition to the above instances, it was found that poisoning from green corn was reported from Queen Annes and
Garrett Counties. The facts accompanying these instances of
poisoning are quite suggestive of nitrate poisonings as described
in the experiments performed at the Wyoming Station. The
evidence in Maryland is only circumstantial however as nitrate
content was not determined in any of the material which caused
the poisoning and until further work is done on this problem,
it must remain only a tentative solution of the cases described.
PLANTS WHICH MAY CAUSE HUMAN SKIN·POISONING
Although stock-poisoning plants are the principal ones under
consideration, brief mention will be made of skin-poisoning
plants.
Poison ivy or poison oak, Rhus radicans L.
These plants cause extremely in'itating skin eruptions on
many people and are found abundantly throughout Maryland.
The question is often asked whether the poison ivy is also
poisonous to animals in any way. It has been observed that
the plants in Maryland are often eaten by cattle but no ill
effects have resulted as far as is known.
The poison ivy is usually a vigorous vine, growing over the
ground or fences, on stumps, or climbing up live or dead trees.
The leaves are three-parted, the three leaflets vary from practically smooth-edged to deeply lobed types and the vines may
be thin and vining or more shrubby and partly erect. In fall
and winter months there are often present clusters of white,
waxy berries.
288
THE :i\IARYL.\ND AGRICULTURAL EXPERIMENT STATION
Poison sumac, poison dogwood, swamp sumac, Rhus Verl1ix L.
The poison sumac is found exclusively in swamps or other
wet land, is a shrub growing up to about fifteen feet in height
and has compound leaves "with seven to thirteen leaflets. The
latter are smooth-edged. The branches and stems are fairly
smooth, usually with dull gray bark and clusters of white
berries as in poison ivy.
FIG. 20. Sumacs. 1, Shining sumac, or wing'ed sumac, Rhus copallina
L.,· 2, fl'all-'rant sumac, Rhus canadensis Marsh.; 3, poison ivy,
Rhus radwans L.,· 4, staghol'n sumac, Rhus typhina L.; 5,
poison swamp sumac, Rhus vernix L. ; 6, smooth sumac Rhus
gl.ab?'CL L.,· 7, Virginia Cl'eeper, five-leaf ivy, often co~fused
WIth po~son ivy ~ut readily d~stinguishcd by the five leaflets.
Its Latm name IS ParthenOc~88us quinque/olia (L.) Planch.
Numbers 3 and 5 are, to many people, dangerous skin poisons.
POISONOUS PLANTS OF MARYLAND IN RELA.'rION TO LIVBSTOCK
289
Wood nettle, Laportea canadensis (L.) Gaud.
This plant grows in low woodland, reaches one to three feet
in height and has stinging hairs over the leaves and stems.
An irritating rash may appear on the skin after touching the
plants.
Several other plants which may cause dermatitis in man are
mentioned in other sections of this report, where they are discussed as being toxic to animals. A large number of weeds and
other plants act on skins that are sensitized to them.
FIG. 21.
Wood nettle (LapoTtea ()anadellsi.~).
290
'rHE :MARYLAND AGRICUL'rURAL EXPERIMENT STATION
MISCELLANEOUS PLANTS WHICH ARE POTENTIAL
SOURCES OF POISONING OF LIVE·STOC}(
A1'l'angecl alphabetically by genera.
FIG.
22.
Aconite, monkshood
(Aconitum
uncinatum L.)
Aconite, Aconitum uncinatum L.
The aconite or monkshood is found wild only in the mountain
zone in Maryland. It grows in moist places and has several
blue, hooded flowers along the upper parts of the tall stalk.
Although no cases of poisoning from the plants have been
recorded from the State it is well to remember that it contains
the toxic alkaloids, aconitine and aconine and might be dangerous if fed in any appreciable amounts to stock.
Corncockle, Agrostemma Githago L.
The corn cockle is often found in wheat or other grain fields
planted from contaminated seed, The plants gTOW up to a yard
in height, have narrow paired leaves appearing opposite on the
POISONOUS PLANTS OF MARYI,AND IN RELATION TO LIVEs'rOOK
291
stem, the flowers are violet or reddish purple and have five
notched petals. The seeds are black with a ridged or rough
surface and are somewhat Iddney-shaped.
Although no instances of poisoning were encountered in this
survey, it is known that the seeds can be poisonous to chickens.
Investigations conducted at this Station by George D. Quigley
and Roy H. Waite (reported in Maryland Station Bulletin No.
325) showed that ground seeds, in amounts 0.25% Or more of
the body weight of the fowl, could prove fatal. It was stated
that only rarely did the birds eat the whole grain but that
cockle seeds separated from grain in screening should be kept
from poultry or animals.
Fly poison, Amianthium muscaetoxicum (Walt.) Gray
As its name implies, ground portions of this plant were in
times past used as bait and poison for killing flies and other
insects. The plant is found only in isolated places in Maryland
FIG. 23. Fly poison (Amianthemum
muscaetoxicum) .
292
'fHE ],URYL.\ND AGRICULTURAL EXPERIMENT S'l'A'l'lON
(a few plants were seen in Prince Georges and Anne Arundel
Counties) and has not been found to have caused poisoning of
live-stock during this study.
Feeding trials conducted by workers in the United States
Department of Agriculture have confirmed the fact that the
plants are poisonous. They were quite rapidly fatal to sheep
and cattle when fed in drenches.
The plant may be found in pine lands, in shaded locations, and
is distinguished lJy its tall flowering stalk with a few scattered
bracts and a short cluster of snow-white flowers which turn
greenish with age. The leaves appear from the base of the
plant, are about a foot long, half an inch wide and have rather
blunt ends.
Scarlet pimpernel, Anag'allis arvensis L.
This plant is found throughout Maryland, occasionally being
quite abundant in pastures and waste fields. It grows quite
close to the ground, often making a rosette-like appearance. It
has short, brown, dotted, paired leaves and single, stalked, dark
scarlet, or rarely blue or white flowers.
The l)lants are said to contain an oil which is regarded as
poisonous to live-stock. No cases of poisoning were encountered
in Maryland. The following instance which occurred in a neighboring part of Pennsylvania was recorded by a reliable source
and indicates that the plant is toxic in this area. In June, 1938,
a number of calves were turned into a small pasture where they
soon trimmed the grass down to within an inch or less from
the ground. Scarlet pimpernel plants which were growing in
with the grass were then more exposed and were heavily grazed.
Several animals were poisoned and six of these died soon after.
The veterinarian attending the case felt sure these plants were
reSl)onsible for the loss of the calves.
May weed, dog fennel, Anthemis Cotula L.
This weed is widely distributed in Maryland, especially in limy
land, and may be responsible for unpleasant flavors or odors in
milk. The plants are also one of the many sources of contact
skin poisoning in humans.
POISONOUS PI"ANTS Oli' MARYLAND IN RELATION
'ro LIVESTOCK
293
FIG. 24. Indian hemp (Apocynum cannabinum) .
Indian hemp, dogbane, Apocynum cannabinum L., Apocynum
androsaemifoliulll L., Apocynum medium Greene
These plants are found throughout the state and have been
seen in abundant stands in some pastures. They may be l'ecognized by their long, slender pods which appear in twos, by the
milky juice and the small leaves which are in pairs. The pods
are much narrower than those of the milkweeds.
No instances of poisoning were encountered in Maryland, but
they are known to contain very toxic substances and in feeding
trials at the Arizona Agricultural EiXperiment Station it was
found that small quantities of dogbane may cause poisoning
or even death in sheep, cattle and horses. s.ymptoms of poisoning include heart stimulation with increased pulse and a rise
in temperature. Discolora,tion of the mouth and nostrils and
soreness in the mouth were also noted as well as dilation of the
pupils of the eyes.
The fact that these plants are potential sources of poisoning
makes them undesirable in pastures and they should be removed
wherever found.
294
THE l\IARYLAND AGRIOULTURAL EXPERIMENT STATION
Hercules' club, Aralia spinosa L.
This vigorous, spiny-stemmed plant is found commonly in .all
parts of the State with the exception of the western, mountamous section. It forms dense growths in certain places, and is
frequently seen as a roadside plant. The thick thorny stalks
are very striking in the winter months, erect, leafless and only
rarely branched.
Although animals are not seen eating the foliage of the
Hercules' Club, it is possible that it may cause trouble on Tare
occasions. Recent feeding trials here have shown the seeds
to be a deadly poison to guinea pigs.
It has been reported that certain individuals have been poisoned, receiving skin blisters, from handling the Toots and bark
of the plants.
Jack-in-the-pulpit, Arisaema triphyllum (L.) Schott.
The most commonly observed action of this plant is the
severe irritation produced in the mouth of persons eating the
corms or bulb-like base. The poisoning is caused by sharp,
needle-like crystals of calcium oxalate which are imbedded in
the soft mucous membranes of the mouth and throat.
Cattle have not been observed eating these plants and it is
not known that they would be dangerously poisonous but they
should not be fed to live-stock. The calla, skunk cabbage and
other aroids wild or cultivated have a similar effect. Animals
have died from eating them in feeding tests.
Marsh marigold, Caltha palustris L.
This well known pasture plant is ordinarily avoided by cattle,
probably because of its acrid taste. Unconfirmed reports were
received from Garrett County which stated that on a few occasions cattle had eaten the plants and had been severely ill
following this. The plant is said to have toxic properties in the
green state only. It is eaten as greens after being boiled, without ill effects. It is rarely seen east of the mountains in
Maryland.
Sweet shrub, Calycanthus fel'tilis Walt., Calycanthus floridus L.
The sweet shrub is found rarely in the western mountainous
sections of the State as a native shrub and is planted as an ornamental in other sections. It has large, aromatic leaves, its
POISONOUS PLANTS OF MARYLAND IN RELATION TO LIVEHTOCK
FIG. 25.
H e1'cules club, (Aralia spinosa), one-tenth natural size.
FIG. 26.
Clusters of black
fruit of Hercules'
club (Aralia spinosa), one-third natural size.
295
296
THE lIIARYLAND AGRICULTURAL EXPERIMENT STATION
flowers are reddish brown and the seeds are said to contain
calycan.thine, a poisonous alkaloid. Reports fro.m Tenness~e indicate that cattle have been poisoned from eatmg th€ folIage of
the plants and it is well to keep live-stock from eating them in
any excessive amounts.
Marijuana, hemp, hashish, Cannabis sativa L.
This is the plant which is used in making the dangerous and
now outlawed "reefer" or marijuana cigarettes. It has powerful
nareotic effects on man but its effect when eaten by animals
has not been reported here.
Hemp is very abundant over thousands of acres in the western states and is occasionally found in Maryland, the plants are
three to ten feet tall, erect annuals with branching, rough
stems and leaves of five to seven narrow palmately arranged
leaflets. Hemp should be removed and burned in accordance
with laws governing drug plants.
Buttonbush, Cephalanthus occidentalis L.
This shrub is found in marsh land or along stream banks and
can be recognized by its shiny, leathery leaves, in twos or
threes on the stern, its flower clusters which resemble a ball
with small white flowers scattered over its surface, and by the
round, stalked seed ball left after flowering.
The plants have bitter-tasting leaves and are said to contain
toxic chemicals, cephalanthin and cephalin which may act as
emetics or produce spasms and paralysis. If the shrubs are
found in abundance in the pasture, they should be fenced off or
removed.
Celandine, Chelidonium majus L.
This plant is a member of the poppy family, has flowers with
four yellow petals and its leaves are deeply cut. The juice is
yellow. It is occasionally found in moist woodland in the central
and western sections of the State but it is said to be only rarely
eaten by animals. The plant contains several bitter alkaloids,
and has been used in medicine and if eaten in quantities by
cattle may cause congestion of the lungs and liver.
Wormseed, Chenopodium ambrosiodides L.
The wormseed is grown in large commercial plantings in
Maryland as a SOUTce of its oil which is used as a vermifuge.
POISONOUS PLANTS OF MARYLAND IN nEL~\'l'IOii" TO LIVESTOCK
297
The plants are quite aromatic and said to be only l'arely eaten
by stock. In large quantities the oil may act as a narcotic and
would be dangerous to animals if the plants were eaten abundantly, as could possibly occur when included in hay.
Meadow saffron or autumn-crocus, Colchicum autumnale L.
This bulbous plant, gTown as an ornamental and flowering in
late summer or autumn, has lilac 01' rose-purple flowers which
resemble those of the crocus. The plants contain a very posionous alkaloid, colchicine, toxic to stock and to humans, and care
should be taken that the plants are not left 'where farm animals
can eat them.
Poison hemlock, Conium maculatum L.
The poison hemlock is a vigorous, branching biennial with
large, finelY-divided, rank-smelling leaves, green to purple, or
purple spotted, hollow, partitioned stems and showy clusters or
umbels of white flowers similar to the ca1'l'ot flowers. It grows
up to six or eight feet high. It is found only occasionally in
Maryland as an escape but is grnwn as a "fern" in some gardens.
This plant may be distinguished from the poisonous water
hemlock (Cicuta. maclI..lata L.) by its much more finely, divided
leaves and its tap-root in contrast to the clusters of bulbous
roots of the water hemlock plant. It also is found in dl'yer locations than the latter which is confined to marshy, or wet land.
The poison hemlock, introduced into the United States from
Europe several years ago, is regarded as the plant from which
death potions were prepared for doomed political prisoners in
ancient times and the death of Socrates is attributed to this
cause. The plant contains the deadly poison, coniine, fatal to
live-stock and humans alike. The symptoms of poisoning in
animals are loss of appetite, bloating, salivation, rapid feeble
pulse and gradual weakening until death. In humans, there is
gradual loss of muscular power, dizziness, confused vision and
perhaps blindness before eventual death.
Fortunately the plant is not abundant in Maryland and no
instances of poisoning have been found. It should certainly be
kept from live-stock, however, and plants grown as ornamentals
should be destroyed by burning when removed from the planting
or :flower bed.
298
THE MARYLAND AGRICULTURAL EXPERIMENT STA'rION
FIG. 27. Lily-o/-the-valley (Convallaria majalis).
Lily-of-the-valley, Convallaria majalis L.
This well-known flower garden plant is known to contain very
poisonous glucosides, convalla11n and convallamwrin. It is not
likely that any great amounts would be eaten by animals but
the plants should certainly not be fed to them.
Bindweed, Convolvulus arvensis L., Convolvulus sepium L.
Reports from other states indicate that hogs have been
poisoned from eating the l'ootstalks of the bindweed. There are
quite active purgative substances in the juice of these vines.
No cases of poisoning from eating the vines, however, were
observed in this investigation.
Rattle-'box, Crotalaria sagittalis L.
The rattle-box, a member of the legume family, is found wild
only rarely in Maryland but several cultivated crotalarias are
now being grown in the State as soil builders. The plants get
their name from the rattling noise which the small seeds make
when they are shaken in the inflated seedpod. Certain species
POISONOUS PLANTS OF MARYLAND IN RELATION TO
LIV}~STOCK
299
of crotalaria are used as forage but the majority are not edible
and in fact are poisonous to stock. Fortunately, the toxic species
are avoided by live-stock. There is the possibility that the plants
might be eaten if included in hay and this should be guarded
against.
FIG. 28.
Scotch broom (CytiSt!8 scoparius).
Scotch broom, Cytisus scoparius (L.) Link.
This plant, introduced from Europe, is found in some sections
of the State, for example in Anne Arundel County, where it is
very abundant west of Annapolis. It is shrubby, has tough,
angled, green branches, very small leaves and golden yello-w
flowers followed by hairy, pea-like pods. The plant is said to
contain poisons which act as heart depressants and may be
dangerous as a feed for stock.
300
'rHE ~['\RYLAND AGRICULTURAL EXPERIlIlEN'r s'rA'rION
Larkspur, Delphinium tricorne Michx, and othe1," Delphinium
species.
Althoug-h larkspurs al'e not found wild in any great numbers
in Maryland, they are occasionally found in large patches in
individual locations, The cultivated forms are quite commonly
grown throughout the State. One of the maj or causes of stockpoisoning in some of the western states is the larkspur and
in view of the close relationship of the local species to these
western plants, it is perhaps best to keep animals from grazing
on the plants, wild or cultivated.
Larkspurs are said to contain several toxic alkaloids which
may cause cattle to lose appetite, and exhibit various symptoms
of poisoning such as repeated falling and rising-, until the animal
is exhausted or death is brought on by respiratory paralysis.
Dutchmans-breeches, Dicentra Cucullaria (L.) Bernh.,
Squirrelcorn, Dicentra canadensis (Goldie.) Walp.
These woodland plants are known to contain a poison, cucullarine, which is toxic or even fatal to cattle, and in the event
they form an appreciable part of the forage available in a pasture, should certainly be removed.
The former plant is well known for its white, two-lobed
flowers from which it gets its name. The latter is similar but
has merely heart-shaped flowers and is also different in its
small, smooth, yellow bulbs about the size of a kernel of corn
in contrast to the pebbly, scaly bulbs of the Dutchman's
breeches. Both plants have very finely cut leaves and are often
used as rock-garden 01' border plants. The bleeding-hearts of
the garden are similar plants.
Foxg-love, Dig-italis purpurea L.
This well-known ornamental plant is the source of digitoxin
and other drugs used in medicine. The green plant is quite toxic
to cattle and horses. Consumption of the plant may cause internal irritation, loss of appetite, and stimulation of the heart.
The plants should be kept from animals as a small amount
may be fa tal.
Horsetail, jointed-rush, Equisetum arvense L., Scouring-rush,
Equisetum prealtum Raf.
These plants which are found throughout the State may
become abundant in moist woods or along embankments or waste
fields. The plants are best known by their tough hollow, ridged
stems which are jointed and will pull apart in sections. They are
said to be toxic to horses, especially, and to contain an alkaloid
equisetin, which acts on the nervous system and muscles. If the
POISONOUS PLANTS OF MARYLAND IN RELATION TO LIVESTOCK
301
animal is allowed to eat the plants for several weeks, even with
other forage, it may gradually decline, stagger, lose its ability
to stand, lose weight, become quite nervous and eventually die.
The following treatment is recommended by the Vermont
Experiment Station: "First stop the feeding of Equisetum, treat
the horse with a purgative as follows: Make a pill from an ounce
of Barbadoes aloes, one or two drachms of ginger and soft soap,
Treat the horse with this and follow with bran mashes twice a
day." Raw linseed oil is suggested as a suitable substitute for
the above treatment.
FIG. 29.
White sna'~eroot, (Eupatorium urticaefolium Reich.)
White snakeroot, Eupatorium urticaefolium Reich.
This plant is found in many sections of the State but is most
abundant in the mountains, in shaded, moist woods. It is best
known for its showy, white, late-summer flowers and the stalked
leaves which are in pairs on the stem or branches.
The plants contain a poisonous substance, tre?netol, which may
cause poisoning of sheep, cattle or even of humans who drink
the milk of affected cows. Symptoms of po-isoning in cattle
include marked inactivity, trembling, general weakness and
depression before death.
This disease, which was quite common in colonial days in
mid-western and eastern states, was known as trembles or milksickness and although recent instances have been reported from
Indiana and other states, none were encountered in Maryland
in the present study.
302
'rHE MARYLAND AGRICULTURAL
)~XPERI:MEN'l'
STA'l'ION
Snow-on-the-mountain, Euphorbia marginata Pursh.
This well known showy ornamental plant contains acrid
milky juice which may produce del'matitis on certain individuals
when they handle the plants. It is not known to be eaten by
animals, although care should be taken to prevent its inclusion
in hay. Euphot'bia corollata L., the flowering spurge, is another
member of this same plant family. It is one of the most common
wild spurges and often forms a conspicuous part of the weeds in
a pasture, It also is quite acrid and unpalatable and might on
occasion be injurious if included in hay fed to live-stock.
FIG. 30.
Indian physic (GUlenia trifoliata).
Indian physic, Gillenia trifoliata (L.) Moench
This plant is common in the mountainous section of the State
and there ~t was said formerly to. have caused poisoning of cattle.
No actual mstances were located III this study.
Eng'lish ivy, Hedera Helix L.
In quantity, the leaves of this common ornamental vine are
reported to be poisonous to animals, due to a glucoside hederin
which is found in the plant.
"
POISO~OUS
FIG.
31.
PLANTS OF MARYLAND IN RELATION TO LIVESTOCK
303
Sneezeweed, (Helenium tenuifolium). Note the drooping
petals of the flower heads, characteristic of this and the
more common species Helenium autumnale, the swamp sunflowm·. The petals are yellow.
Sneezeweed, Helenium autumnale L., bitterweed, Helenium
tenuifolium Nutt.
The sneezeweed is found throughout the State and may be
known by its winged stem, yellow flowers, the petals notched at
304
THE MARYLAND AGRICUL'ruRAL EXPERIMEN'l' STA'l'IOK
the end and spreading out and downward from the flower head
at maturity. The leaves are wider and more toothed than those
of the much less frequent bitterweed shown in Fig. 31, but the
flowers are practically the same.
These plants are toxic to animals when eaten in quantity and
may cause general weakness, stupor, chewin,g motions, frothing
at the mouth, and even death, particularly in sheep. The plants
are apparently not eaten under normal cil'cumstances as they
are bitter. If the plant is common in the pasture it should be
removed by cutting.
FIG. 32.
Cow-pa?'snip (Hemcleum lanatum). This plant was 4
feet high.
Cow-parsnip, Heracleum lanatum Michx.
This plant is found in the central and western sections of
Ma!'yland. It is apparently on~y rarely eaten by animals because
~f Its low palatabIlIty but as It has been suspected of poisoning
h:re-stock, It should not be fed to them. It was fed to guinea pigs
wlthout bad results.
POISONOUS PLANTS OF ;\URYLAND IN RELATION TO LIVESTOCK
FIG. 33.
305
Flag or wild iris.
Iris, blue flag, Iris versicolor L.
The blue flag is known to contain a poisonous substance in its
rootstalks, il'isin, which causes irritation or purging in animals
which may eat abnormal amounts. It has not been reported that
the leaves, stalks or flowers are toxic but they probably should
not be left where animals could eat them in large quantities,
In British Columbia, it was reported that several calves were
killed from the effects of eating clumps of the rootstalks of the
wild iris. A post-mortem showed dark patches in the lar,ge intestines of the poisoned animals and also dark coloration in the
kidneys, liver and spleen.
306
'I'HE :i\lARYLAND AGRICULTURAL EXPERIMENT STATION
FIG. 34.
Indictn tobacco (Lobelia inflata).
Indian tobacco, Lobelia inflata L.
The Indian tobacco contains a severe narcotic poison which
may cause nausea, dilation of the pupils, exhaustion and even
convulsions and death if eaten by animals. The plant has milky
sap which contains the extremely irritating, bitter poison and is
not likely to be eaten while growing but there is the possibility
that plants may 'be included in hay and cause poisoning. The
great lobelia (L. siphilitica L.) and cardinal flower (L. Cardinal.is L.) are also said to contai11 toxic materials.
POISONOUS PLANTS OF MARYLAND IN RELATION ']'0 LIVESTOCK
FIG. 35.
307
-VYild lupine (Lupinu8 perennis).
Wild lupine, Lupinus perennis L.
Although a number of relatives of this Maryland lupine are
known to contain toxic alkaloids and are recognized in the west
as poisonous plants, it is not known that the above species is
actually poisonorus. The plants are found chiefly in the central
section of the State, in open waste places, and it is perhaps best
to prevent live-stock, especially sheep, from grazing on the lupine
for any extended period.
Moonseed, Menispermum canadense L.
This vine is found in moist woodland, usually in the central
section of the State. It resembles the wild grape in the shape of
the leaves hut the edges of the leaves of the grape are toothed
308
'l'HE NAItYLAND AGRICULTURAL EXPERIMENT STATION
while those of the moonseed vine are not. In addition the seed of
the grape is ovoid while that of the moonseed is moon-shaped
or like a notched circle.
In the event abundant growths of this vine are present in the
pasture or woods, care should be taken .that grazing animals do
not have access to them and the berrIes should be kept from
children who might mistake them for wild grapes.
Oleander, Nerium Oleander L.
The oleander is sometimes ,grown in Maryland as a potted
house plant, set outdool's in summel' and inside in the winter as
it is not hardy in this latitude. They should be kept away from
gra.zing animals as there are very poisonous materials in the
leaves. Some reports from other states record the deaths of
horses and cattle which have eaten oleander foliage, and sheep,
goats and humans are said to be susceptible to the poison also.
The poison present acts on the heart and blood vessels.
Poppy, Papaver species
The source of opium which is obtained from the juice of the
ulll'ipe pods is Papaver somniferum L. A number of narcotic
alkaloids are present in poppies and they are definitely toxic to
animals. Papaver orientale L. and P. 'i'hoeas L. are grown in
Maryland as ornamentals and should be kept from grazing livestock. Another species, P. clmbium L., is frequent in some Maryland fields.
Poke, pokeberry, Phytolacca americana L.
The poke is very 'commonly found growing in waste places
and in farm yards and pastures throughout the State. No instances of poisonin,g of live-stock were encountered in the present
study of conditions in Maryland, but it has been l'eported from
other states that cattle have been killed from eating quantities
of the plants when other forage was scarce. Ordinarily the plant
is not eaten by live-stock. Other indications of the toxic nature
of the plant are that children have been poisoned by eating the
berries and the report personally recorded in Garrett County
that an adult man very nearly died following taking a "cold
preparation" made up from the roots of the poke.
The plant contains a toxic alkaloid, phytolaccine, which is said
to be responsible for poisonings from eating the plant. The young
sprouts of the plant are often eaten as greens.
The action of the poison contained in poke is said to be cathartic, and fats or oils have been recommended as remedies in the
events of poisoning of stock.
POISONOUS PLANTS OF lIIARYLAND IN RELATION TO LIVESTOCK
309
May-apple, mandrake, Podophyllum peltatum L.
The May-apple, a source of certain dn\gs used in medicine, is
found frequently in the State in moist woodland clearings or
pastures at the edge of woods. The rootstalks and green fruits
are said ~o contain a bitter substance, podophyllin, which acts as
a purgatIve, also causing cramps, na usea and vomiting in humans.
Cattle which may eat the plant are said to give milk which is
purgative to humans consuming it. The ripe fruits are edible.
It is easily recognized by the stalh about a foot high bearing
one or two large, lobed, umbrella like leaves, with a white flower
in spring from the fork of the stem.
Rhubarb, Rheum Rhaponticum L.
Although the stalks of the rhubarb are edible, the leaves have
large quantities of oxalates and are to be considered poisonous.
Although no cases of poisoning were observed' in Maryland,
from other sources it is known that hogs and cattle have died
following eating quantities of the leaves which were thrown to
them for feed. The hogs exhibited salivation and had convulsions
before death.
Conefi()wer, Rudbeckia laciniata L., Black-eyed·Susan,
Rudbeckia birta L.
The coneflower is tall with showy yellow flowers and is found
along streams 01' in moist woodland. A variety is cultivated
as Golden Glow. The black-eyed-Susan, the State flower of Maryland, has rough and bristly-haired stems and leaves and is a
well known wild and cultivated plant. These two plants have been
suspected of causing poisoning of }Jigs and cattle in other states
and should be considered in stock-poisoning cases in Maryland
as possible offenders.
Sheep sorrel, sour-grass, Rumex:: Acetosella L.
This very common weed, found ,usually on sterile or acid soils,
is usually avoided by live-stock. The plants are said to contain
high concentrations of oxalates and for this reason may be
injurious to animals.
Elder, Sambucus canadensis L.
AlthouJ~'h the leaves of this common pasture shrub are often
grazed with no apparent ill effects, it is said that the roots and
bark contain toxic substances. Hogs may be poisoned by eating
the roots and reports have also been seen in the literature jn
which the poisoning of children has resulted from using the
310
'£HE MARYLAND AGRICULTURAL EXPERIMENT S'r_-I.TIOX
hollow stems as blow guns. The ripe berries are commonly eaten
in pies or used in preparing wine.
Elder may at first appearance be confused with the poisonous
water hemlock as they both grow in moist situations and both
have clusters of small white flowers. They are in fact often
found growing together. The leaves of the elder appear in pairs
on the stem while those of the hemlock grow singly. The leaves
of the hemlock are more divided also and the plant is not woody
as the elder is. The tuberous roots in clusters which are characteristic of the hemlock may also serve to distinguish it from the
elder which has more fibrous roots.
Bloodroot, Sanguinaria canadensis L.
The bloodroot, found occasionally in shaded woodland in the
central counties of the State, is known for its thick rootstock
with red juice and its thick reddish-green leaves. It is in the
same plant family as the poppy and is said to contain acrid substances in the root which are toxic to animals.
Groundsel, Senecio aureus L. (and other species)
Although the senecios found in Maryland have not been definitely associated with stock-poisoning, related species in some
western states are recorded as having poisoned cattle and horses.
There the symptoms of poisoning recorded include general emaciation, continuous walking and butting into objects, and postmortems have revealed yellowish mucous membranes and in
cattle lesions of the liver.
The groundsel is an erect herb, grows from one to three feet
in height, has deeply cut leaves along the stem and conspicuous
:fiat~'topped clusters of numerous yellow daisy-like flowers in
spring.
American yew, Taxus canadensis Marsh., English yew, Taxus
baccata L., Japanese yew, Taxus cuspidata Sieb. and Zucco
Yews are frequently planted as ornamentals in the State and
the American yew is rare in the mountains of the extreme western part of Maryland. The English yew has been responsible for
~eath of live-stock in EUrope, as a very poisonous alkaloid, taxine,
IS found throughout the tree. Trimmin,gs from yews should not
be fed to animals. It is reported that the American yew should
also be considered dangerous although no instances of poisoning
from this species have been found in the literature. The Japanese
yew is the most commonly planted' species in Maryland.
311
POISONOUS PLANTS OF lI[ARYLAND IN RELATION TO LIVESTOCK
TABLE 1.
SUMMARY m' RECENTLY RECORDED CASES OF PLANT POISONING
OF LIVE· STOCK IN :MARYLAND.
COUN'l'IES IN 1Il... RYLAND
ANurALS
I I I xl I I xl xl xl xl xl xl xl I xlxl xl xl I xl "I xl xl
I xl xl xl I I I
1,1 I xl I I xl "I xl I xl xl xl I xlxl I xl I I xl I I
I xl I xl I I I x
I Ixllxll I I I Ilxl Ilxlxlxlxl I blxl I
Ixlxl Ixl I
\
Black Nightshade
I I I xl I I xl xl I xl xl I xl I xl I I xl I I I "I I I I xl xl xl xl xl I I
Snow·drop (bulbs)
I I I I I I I I xl xl I I I 1xl I I xl I I xl I "I xl I I I xl I I I I
Jimson Weed
I I I xl I I xl I I I xl I xl I xl I I xl I I I I I I I xl xl I xl xl I I
Cockleour (seeding_)
I I I xl I I xl xl I I xl I xl I I I I xl I I xl I I I I I xl I xl I l:xl
Sorghum
I I I xl I I xl I I 1xiii 1 I I I xl \ \ \ 1'\ \ \ I xl x\ I \ I I I
Black Locust
I I \ I I I xl I I I xl I I I I I I \ I I I I I I I xl xl I I I I I
Lima Bean (vines, pods) I I I I I I I I I I I I I I I I I xl I I xl I I xl I xl I I I I I \
Buttercup
I I I I I I xl I I I I xl I I I I I I I I I I I I xl I I I I I I
Bracken
I I I I I I I I I I I xl I I I I I xl
I I I I I I xl I I I I I I
Peach (kernels)
I I I I I I xl I xl I I I I I I I I I
I I I I I I I I I xl I I I
Ealse HellebDre
I I I I I I I I I I I xl I I I I I I I I I I I I xl I I I I I I
Shepp Lamel
I I I xl I I I I I I I I xl I I I I I I I I I I I I I I xl I I I I
TobaccD
I I xl I I I I I I I I I I I I I I I I I I I I I I I xl I I I I I
Oak (sprouls)
I I I I I I xl I I I I I I 1 I I I I I I I I I I I xl I I I I I I
Kentucky Coffee-tree
I I I I 1 I I I I I I I xl I I I I I I I I I I I I I I xl I I I I
...:L;:;:07::b::::lo~ll!.-y~P:.::in:::.e_ _ _+1+I-;\~I~I--+-I-+1.....,1:--+1-;1_+1-+1_1f-+141-:1:--+141--+-1-+I.::,x\:--+141-+-1 I xl I I I I I I
Milkweecl
I I I I I I I I I I I I I I I xl I I \ I I I I I I I I xl I I I
Horse·chestnut
I I \ xl I I xl I I I I I I I I I I I I I I I I I I xl ! I I I I I
Privet.
I I I I I I I I I I I I xl I I I I I I I I I \ I I I I xl I I I I
Box
I I I I I I I I I I I I I I I I I xl I I I I I I I I I xl I I I I
A!sike Cluver
I I I I I I I I I I I I I I I I I xl I I I I I I I I I xl I I I I
St.•1ohnswort
I I I xl I I I I I I I I I I I I I I I I I I I I I xl I I I I I I
Jnhnson GraS8
I I I I I I I I I xl I I I I I I \ I I I I \ I I xl I I I I I I
Potato (greenecltubns) \ I I I I I xl I I
I I I I I I I xl I I I I I I I xl xl I xl I I I
Matrimony Vine
\ I \ \ I I I I I
I I xl I I I I I I I I I \ I \ xl xl I I I I I
COl'll (!nepn pars)
\ \ \ I I xl I x\ I
I xl I I I I I xl I I I I
I I xl I I \ \ I I
111111111111111111111111111111
WilrlBlack Cher1')'
jllountain Lanrol
Vv.t,CT}l,nnlock
r
Pl.nts damaged Or
infectpll with run~i
Corn (moldy)
\ ,\ I\xl\ I\xl\xl\x,\ II xl\xl\ \I \I xl\xl\xl--'I-....!-I
\ \ \-'I-"~I
\ \"+'1--7-+\
II \-+,-x+-I
\ \x+I-I~x+1
\ IIIx-+'I-x+-I\+1I
Sweet Clovers (daRla(!erl) I I I xl I I xl xl I
Oats (moldy)
Rye (el'g-otizru)
PaSJlahlm (rt'gotizcd)
I
xl I xl xl xl xl
I I I I I I xl I I I I I I I
I I I I I I I I I I \ I I I
I I I I I I I I xl I I I I I I
I xl
I x\
I xl
I I
I
I
I
I
I I "I
I I \
I I I
I I \
I ' xl xl
I I I xl
I I x\ I
I I I x\
I
I
I
I
I
I
I
I
I
I
I
I
I
\
I
I
Table I summarizes the recently recorded cases of stock-poisonin,g and gives the animals affected by each plant as well as
the counties in which the cases occurred, The number of cases
recorded for a particular county may not give the complete picture for this county as several factors modify this tota1. The
time spent in the county, the number of dairy or stock farms
and also the number of veterinarians practicing in the county
all contribute to the variations indicated in the table.
I
I
I
I
312
THE MARYLAND AGRICULTURAL EXPERIMENT STATION
It is thought that the table will give some indication of the
species of plants which are most likely to be responsible for
poisonil1,g of livestock and perhaps in this way shorten the time
necessary to solve poisoning cases. The plants involved in the
greatest number of cases have been put at the top of the list and
it is evident that the first few are responsible for the great
majority of cases recently occurring in Maryland.
ACKNOWLEDGMENTS
The valuable cooperation of the Maryland State Livestock
Sanitary Service Laboratory and its staff is acknowledged and
the aid given by many of the veterinarians practicing in Maryland, is .appreciated. Considerable assistance was also received
from the County Agents in each of the counties in the State,
especially in the location of the farms surveyed in this investigation.
Material of a technical nature was taken from some of the
standard works on toxicology and special mention is made of the
works of Pammel, "Manual of poisonous plants," of Steyn, "The
toxicolo,gy of plants in South Africa," and of Muenscher, "Poisonous plants of the United States." Information concerned with
cases of stock-poisoning in states other than Maryland was
gathered from bulletins on poisonous plants from the Agricultural Experiment Stations of the several states and acknowledgment is made of these sources. The published works of several
investigators in the United States Department of Agriculture,
pa.rticularly those of Chestnut, Marsh, Clawson and Couch, were
consulted frequently and use of some of this information is
appreciated, as well as personal consulta:tions of the specialists
engaged in this work, in particular Dr. J. F. Couch.
INDEX TO PLANT NAMES
Page
Claviceps ........................................... 283
Clover .............................273, 285
Cockle ................................................. 290
Cocklebur ......................................... 260
Colchicum .......................................... 297
Coneflower ......................................... 309
Conium ............................................. 297
Convallaria ..................................... 298
Convolvulus ............................... 298
Corn ....................................... 282, 286
Cow-parsnip ..................................... 304
Crotalaria ............................................ 298
Crowfoot ..... ............... ............. ....... 268
Cytisus ................................................ 299
Page
Aconite ................................................ 290
Aesculus ............................................. 270
Agrostemma ........ ........ . .............. 290
Allium ................................................ 259
Alsike clover ......................... 273, 285
Amanita . . ................ ...... .......... ....... 282
Amianthium ... .... .......... ................ 291
Anagallis ......... .......... ..................... 292
Anthemis .................................... 292
Apocynum ...................................... 293
Apple ................................................. 277
Aralia ............................................... 294
Arisaema .............................................. 294
Aroids .................................................. 294
Arrow grass .....................277, 278
Asclepias ..................................269, 270
Bindweed ......................................
Bittersweet ......................................
Black-eyed-Susan ........................
Bitterweed ...................................
Bloodroot .........................................
Bluebottle ..........................................
Box ....................................................
Bracken ..............................................
Buckeye ...............................................
Buckwheat ....................................
Brassica ..................................................
Buttercup ............................................
Buttollbush .....................................
Buxus ....................................................
298
263
309
303
310
259
273
271
270
285
285
268
296
273
Calla ....................................................
Caltha ..................................................
Calycanthus .................................
Cannabis ...............................................
Cardinal flower ..........................
Castor-bean ........................................
Celandine ............................................
Cephalanthus ..................................
Chelidonium .......................................
Chenopodium ..................................
Cherry ...................................................
Choke cherry ........................ ......
Cicuta .................................................
294
294
294
296
306
270
296
296
296
296
277
277
256
312A
Datura ...............................................
Delphinium ......................................
Dicentra ...................... ...... ............... ....
Digitalis ........................................
Diplodia ........................................... _.....
Dogbane ..........................................
Dogfennel .........................................
Dog laurel .......................................
265
300
300
300
282
293
292
254
Elder .....................................................
English ivy ........................................
Equisetum ........................................
Ergot .........................................................
Eupatorium ....................................
Euphorbia ...........................................
309
302
300
283
301
302
Fagopyrum ........................................
False hellebore ...............................
Fern .............................................271,
Feterita ...........................................
Flax . .. ........................................ 277,
Fly poison ..........................................
Foxglove ..........................................
Fungi ..................................................
285
275
297
280
282
291
300
282
Garlic .............................................
Gillenia ......... ............. ...... ....................
Glyceria ...............................................
Grain ............................... 282-283,
Grape hyacinth .............................
259
302
281
286
259
INDEX TO PLANT NAMES-(Continued)
Page
Marsh marigold ............... ..... ..... 294
Matrimony vine ............. 263, 266
May-apple ........ .. ................. 309
Melilotus .................................... 261
Menispermum ...... .................. ..... 307
Milkweed ........................................... 269
Milo ................................................. 280
Moonseed .......................... ................. . 307
Mountain laurel ............................. 252
Muscari ............................................ 259
Page
Groundsel .................................... 310
Gymnocladus ..... .... ... .. ........ 266
Hedera .....................................
HeleniUln .......... .........................
Hellebore ...... .... .......... .. . ............
Hemlock ...................... 255, 256,
Hemp '" ..........................................
Heracleum ..... ........... . ..........
Hercules' club . ......................
Horsechestnut ......................
HOl'senettle ................. ................
Horsetail .......................................
Hypericum ................................
302
303
275
297
296
304
294
270
265
300
285
Indian hemp ...............................
Indian physic ................................
Indian tobacco ......... . ...............
Iris ................................................
Ivy . ................ ....... ........... . ....252,
293
302
306
305
302
Jack-in-the-pulpit ....................
Jimson weed ..................................
Johnson grass ..................277,
Kafir .................................................
Kalmia ................................. 252,
Kentucky coffee tree .................
Knotweed .......................................
294
265
280
280
254
266
285
Laprotea ..........................................
Larkspur ................... .................... .....
Laurel .............................................
Leucothoe ........................................
Ligustrum .................... ... ..................
Lily-of-the-valley .. .............. ..
Lima bean ........................... 277,
Linum .........................................
Lobelia .........................................
Locust .............................................
Lupine ................................................
Lycium . ........................... ..... ...... ... ..
Lyonia ..................................................
289
300
252
254
273
298
280
282
306
262
Mahogany ...................................
Mandrake .....................................
Manna grass .... ,.................. 277,
Mal'ijuana .... ..... ..... ..................... ..
266
Nerium ......................................
Nettle ..............................................
Nicotiana .....................................
Nightshade ........................... 262,
308
289
265
263
Oak ........................................................ 271
Oleander .............................................. 308
Ornithogalum... . ...................... 257
Papaver ...............................................
Pal'thenocissus ..............................
Paspalunl. ...........................................
Peach ................................................ 277,
Phaseolus .......................................
Phytolacca ..........................................
Pimpernel ............................................
Pine, Pinus ..........................................
Plum .......................................................
Podophyllum .....................................
Poison ivy ............................................
Poke .........................................................
Polygonum ....................................
Poppy .......................................................
Privet ........................................................
Prunus .................................................
Ptel'idium ..........................................
308
288
283
279
280
308
292
274
277
309
287
308
285
308
273
278
271
Quercus .............................. ................... 271
307
Ranunculus ....................................
Rape ......................................................
Rattlebox ...............................................
Rhododendron ....................... 253,
Rhubarb ...........................................
Rhus ............................................... 287,
Ricinus .....................................................
266
254
309
281
296
312B
268
285
298
254
309
288
270
INDEX TO PLANT NAMES-(Continued)
Page
Robinia .. .... ......... ..... .......... ..... ....... 262
Rudbeckia ..... ................................. 309
Rumex ..................................................... 309
Sambucus .......................................
Sanguinaria .............................
Scotch broom ................................
Scouring rush ...............................
Senecio .............. ............. . ................ ......
Sheep laurel ......................................
Sheep sorrel ......................... _...........
Skunk cabbage ..............................
Smartweed .......................................
Sneezeweed ........................................
Snowdrop ......................................
Snow-on-the-mountain ...........
Solanum ..................................... 262,
Sorghum ................................... 277,
Sour-grass .............. ...... ........ ...........
Spurge .....................................................
Stagger bush '" .............................
Star-oi-Bethlehem ..................
St. Johnswort ......................
Page
Sumach .................................................. 288
Sudan grass ............................. 280
Sweet clover .................................. 261
Sweetshrub ..................................... 294
309
310
299
300
310
254
309
294
285
303
257
302
264
279
309
302
254
257
28fi
Taxus ................................................... 310
Thornapple ...................................... 265
Toadstool .......................................
Tobacco ............................................
Trifolium ..............................273,
Triglochin ....................................
282
265
285
278
Veratrum ........................................ 275
Virginia creeper ............................ 288
Water hemlock .................. 2G5,
White snakeroot .........................
Whild chel'l'Y .................................
Wormseed .........................................
256
301
277
296
Xanthium " .............................. 260
yew ........ ..................................... 310
312C
The Bulletins Named Below Are Available For Distribution.
These Bulletins are sent free of charge to any address upon application.
EXPERIMENT STATION BULLETINS
BUlletin No. 368, Sept., 1934, Spray Residue Removal trom Apples .
•,
,. 370, Nov., 1934, The Physical and Ohem. Properlles of Red Clover ltoots.
..
.. 372, J &n., 1985, Nitrogenous :Metabolism in Irish Potatoes During Storage.
878, July, 1935, A Survey of tIl. Sheep Industry of Mal·yland.
379, July, 1935, Fattening Thin Native Lambs.
!I80, July, 1986, The Effect ot Size and Type of Ewe on Production.
BB1, July, 1935, Tax Delinqaency in Maryland.
882, July 1935, Production, :Marketing and Consumption of Tobacco.
383, July, 1935, Ohanges in the Composition of Green SnaIl Beans.
384,
1935, WEtt'°ermct s~fd F~:~i1r:~rdT:!~~;"ent. on Tomatoes.
B86, July,
Sept., 1936,
U~; ~~:.::
mi; ¥l:~!:~S~\~~ai::;'t:rP~~~~;~i;~r8;3u6~~l';'iCal
Com·
position of Red Clover Plants to Winterhardiness.
39S, Feb., 1936, Tlte Properties and Stability at Wllipping O1'."m.
394, Mar., 1936, Sale of Dairy Products "t Roadside lIiarkets in Maryland.
396, May, 1936, Part I. The F"l:"m Credit Situation in Maryland.
~~~: ~~l~: m~: ¥K~d~~t!~nE':.~~";:~.ding of Early Lambs.
400, July, 1936, The Vinegar Gnat. or Pomace Flies.
402, Aug., 1936, StF~~e"r~~I~~~;:'b~l~~a;:~ctors in the Agglutination Test
408, Sept., 1936, StrawbeTl'Y Fertilizer Studies In lIIarylllnd.
404, Sept .. 1938, Dairy Herd Organization and Income On Dairy Farms.
405, Oct., 1936, An Economic Study of Dairy Farms in Maryland.
406, Nov., 1936, An Economic Study of Livestock Fal'ms in Maryland.
407, Dec., 1930, Marketing Fruits and Vegetables by Motor Truck
40B. Jan .. 1937, Report of Dairy Inspection Sel'vice for 1936.
409, May, 1987, Th .. Baltimore Wholesale Fruit and Vegetable Markets.
411, Apr., 193B, (Special Bulletin) Legume and Grass Silage.
412, Oct., 1937, Economy in County Government.
413, Oct., 1937, Some Factors Affecting the Aocuracy of the Babcock
Test on Composite Samples of :Milk.
414, ll'eb., 193a, :Metabolism in tI,. Corn Ear Worm. I. Studies on Fat
and Water,
415, Feb., 1938, Organization and Operation of :Marsh Market in Balti·
more and Proposed Improvements,
416, Apr .. 1938, Winter Barley in Maryland.
417, June, 19S5, Effect of Cash'ation of Lambs on Tl,.lr Development
and Quality of Meat.
41S, July, 1938, Does It Pay to Grade Eggs!
419, Juno, 1988, The Plum Ourculio.
421, Oct., 1988, An Economic Survey of Farm Orchards In Counties
Near Baltimore, Md., and Washington, D. O.
422, Oct.. 193&, Standard of Living on Carroll County, lIIaryland, Farms.
424, Jan., 1989, An Economic Study of Land Utilization in the To·
baceo Area of Southern Maryland.
425, Feb .. 1989, Variety and Strain Trials of Alaska and Sweet Types
of Peas for Canning in Maryland.
426, Mar" 1989, An Economic Study of the Hatchery Industry in Md,
427, July, 1989, The Production and Marl,eting of Honey in Maryland .
.. 42S, Aug. 1989, Qualities of Hams and Rapidity of Aging As Affected
By Curing and Aging Conditions and Processes.
429, Aug., 1939, Marketing :Mnl'yland Turkeys.
430, Oct.. 1939, Economic Analysis of the Baltimore Egg lIIarl<et.
431, Jan., 1940, An Economic Study of the Maple Pl'oduo.ts Industry in
Garrett County, :Ma~yland.
432, Feb., 1940, Types of Farming in Maryland.
433. May. 1940, Potato Disease Control Studies on the Maryland Enst·
ern Shore.
434, JUlie, 1940, lIfal'kcting Farm Pralluct. Tln'ough Comlllunity Auctions.
435, July, 1940, Measuring Inequalities in Farm Property A.scssments
in Maryland.
436, Allg .. 1940, Production and Marketing of lIIaryland Sweet Potatoes.
n 437, Oct., 1940, Rural Community Ol"gnnhntion in WElshing-ton and
Fl'(ldC'ricl{ (iounth~s. 1\Il1rylnllrl,
438. No\, .. 1940, Tl,. State Piseal Capacity of lIfal'yland and othe,'
S(lol('ctC"cl Rtl1tes.
439, ]\[ar., 1941, RtlldiAS on Corn Enr Worm Contl'ol.
440, Apr., 1941, Clnssiiicn.tion of Agl'icultllrnl ArPlls, Frederick County,
JI[aryll1nll.
441, May, 1941, Status anll Trenll of Agl'icultUl'al Cooperation in Mal'y,
land.
AI, July, 194], Fee,l all(1 Othe,' Costs of Pl'on neing Jllnrket. Eggs.
A2, Aug., 19·11 Oharactel'istics of }~al'm Property Assessments in J\!arylana, After the Last Reassessment.
AS, Oct. 1941, Economic Aspects of the Distilling Industry in JI[[Il'Y'
lond.
AA, Oct., 1941, TIle Potnto Entp1"l~ri"" in Gar!'ott ()ollnty, Man·land.
A5, Nov., 1941, Fn..l'mel's· ]..futua.I lhl'o Insul'anN' in ]\ICL-l'yland.
An, Noy., 1941, Vlllue of IL Ferrn('ntRtloll B)·.Prollnct ill POllltl'Y Noerl~.
A 7, 1\[0.1'., 194~, The OascheRrer in Mllrvlanll.
AS, l'rIar., 1942, Short-TN'm Cl'oclit on' the Lower Eltstcl'n Shore of
lIIlll'l']l1nrl.
A9. AuI' .. 194-2, Ext£'nt of Chan_£es ,!l~d _1E~~}~~~z~:i~~o~~!;'n~~rm Property
The Board of Regents of the University of Maryland.
HENRY HOLZAPFEL, In., Chairman... ...... _......................__ ............... _........... _._.Hagerstown
nOWLAND K. ADAMS, Vice-Chairman ............ .......... __ ................. ""_""" ........ Baltimore
MRS. JOHN L. WHITEHURST, S ect·otat·y .... .... _." ...................... ''''' ...........Baltimore
J. MILTON PATTERSON, T?·easu?·e?·.......... ......... ................ _....... .. ............. Baltimore
W. CALVIN CHESNUT................ _................................"........ ...... . ............................. Baltimore
WILLIAM P. COLIC, JR.... .......... .
................................._......................Towson
.TOI'IN E. SEMMES............ ....................... ...... ............... ..........
.. "__ -'''''''''' "__... Baltimore
P. C. TURNER .................................. _... '" ..... ........ . ........... ..
. .......... "'"'''' ...... Parkton
'* 'fhe BOfucl of Regunts and l\Ial'ylnud State Board uf _'-lgl'icultUl'C consists of cloven
menl bers.
A~
prct:;cnt, there are tlnee vacnncies.
Executive Officer of the Board and President of the UniVersity,
H. C. BYRD, LL.D., College Park
S'l'ATION STAFF
R. B. CORBE'l"l'. Ph.D., DIt'ector
AGRICULTURAL ECONOMICS
S. H. DeVault, PI1.D., P,·of. Agr. Eeon.
W. P. Walker. IlLS .. Assoc. Prof. Agr. Eoon.
A. D. Hamilton, M.S., Asst. Prof. Agr. l1:eon.
A,.\h"r 111. Ahalt. M,S ABSt. Prot. Agr. Bdue.
R. Ji'. Blll'dette, J\l.S.. l Bst. Agr. ECDU.
P. R. Poffenberger, M.S., Illst. Agr. )TIeoll.
BACTERIOLOGY
L. Ii. James, Ph.D .• Prof. Bact.
t1Iichnl'1 Pc!t:ZM·, Ph.D., lnstr. Bact.
ENTOMOLOGY
E. N. Doty, PIl.D .• Prof. Ento.
H. S. McGonnell, ]II.S., ASBOC. Prof. Enlo.
L. P. Ditman, Ph.D .• Asst. Prof. Ento.
G. J. Abral11s, M.S" Asst. Prof. Ap!cultur.
AGRICUL'l'URAL ENGINEERING
R. W. Carpenter. A.B., LL.Boo Prot. Agr. Jl:ngr.
G. J. Burkhurdt, M.R .• Asst. Pr·of. Agl'. Bng,·.
DAIRY DEPARTMENT
A. V. Krewateh, ]II.S., KE., Assoc. PrOf. Agr.
l!:ngr.
K, L. T'll']c. Ph.D., Prot. D.iry Husb.
AGRONOll!Y
C. W. Englund, Ph.D .• Prof. Dairy IIIfg.
W. B. KomI'. Ph.D .. Prof. Agl'onomy
L. A. Moore. PIl.D., Prof. Dairy Husb.
R. G. Rothgeb, Ph.D., Assoc. Geneticist
~1. H. Berry, M.S., Assoc. Prof. Dairy Husb.
R. P. Thomas. Ph.D .. Prof. Soils
Glenn T. Hoffman. B.S., A8Bt. DRirJ' Insp.
II. ll. Winant, M.B .. Asst. Prof. Soils
G. F. l\I~digRn. Ph.D" Asst. Proi. Soil.
HORTICULTURE
A. W. Woods, B.S .. lnst. Agronomy
C. H. 1I11>honey, I'h.D., Prof. Oler.
S. P. Stabler, B.S., Asst. Agroll.
Albert Wllite, B.S .• As"t. Agron.
A. L. Sclu·,,<1ol'. Ph.D .• Prof. Hort.
A. D. ITo(l.clll'Y! Ph.D" lm,;L Agl'on.
E. P. Walls. Ph.D., Pl'of. Canning Crops
A. O. Kuhn, M.R., Asst. Prof. ,1.1';1'011.
I. C. Haut, Ph.D .• Assoc. Prof. Pomo!.
l!'. B. Lincoln. Ph.D., Assoc. Prof. PIt. Prop.
ANIMAL HUSBANDRY
H. A. :Hunter, M.S., Assoc. Prof. Oanning
F. H. Loinbach. Ph.D .. Prof. Animal Husb.
Crops
DeVoe Meade, Ph.D., Prof. Animal Husb.
Jael<
Amatt. B.S., Inst... Hart.
J. B. Outhouse, lII.S., Inst1'. Animal Husb.
D.lIL Bniley, 11.1'1 .• Illstr. & Ass!. 01el'
ANIMAL PATHOLOGY
tHowal'<1 Aliel', rh.D., AHst. Prof. HOl't.
M. Ii'. Welsh. B.S .• D.V.M., Prot. Vet. Med.
Herman Todd, B.s., A.,t. Hart.
A. L. B1'1leolmel', B,S., D.V.M., Prof. l'ath.
C. W. Ritz. Ph. D .. Asst. Pomal.
R. lIL DeVolt. IIUt. D.V.M .. Assoc. P~of. Path.
L. J. Poclms. :Io[.S., D.V.lI1., Assoc. Prof. Path.
POULTRY f1:USBANDRY
M'I5;~J;.Rabstein, B.S., D.V.Moo Asst. Prof.
IlL A. JulI, Ph.D., Prof. Poult. HUBb.
Clyde Bean, D.V.M., ABBt. Prof. Path.
G. D. Quigley. B.S' .• Assoc. Prof. Poult. Husb.
H. R. Bird. Ph.D., Assoc. Prof. li'utrition
BOTANY. PLANT PATHOLOGY AND
R. E. Plt!l!ips, P11.D., Assoc. l?rof. Poult.
PHYSIOLOGY
Husb.
·C. O. Appleman. Ph.D .. Prof. Tlot. & Pit. PhY8.
Ronl1Jrl Bandonl Pll.D., P,·of. Bot.
R. A. Jehle. Ph.D .. Prof. PIt. Path.
R. G. Brown. Ph.D., Asst. Prof. Pit. Phys.
H. G. DnBIlY. Ph.D., Asst. Prof. Pit. Phys.
M. ·W. Woods, Ph.D .• Asst. Pl'ot. PIt. I>ath.
F1. A. Walker, Pll.D., Asst. Prof. Pit. Puth.
1,V F . .T~fferR, Ph.D .• 1n.t1'.• PIt.. Path.
C. E. Cox. '111.8., Inotr. PIt. Puth.
tHo G. SIMk, Ph.D .. Asst. Pit. Pllys.
tJumcs 'III. elwin, M,-ft. As"oe. 1'1'01. Poult.
Prod. &; Marketmg
Chal'le. Williams, M.S., Inst,.. Poult. Husb.
SEED INSPEC'l'ION
F. S. Holmes. M.S .• Seerl Inspector
EllenP. Emack. Seed Analyst
Olive lIL Kelk. Seed Annl,st
t,fo1l1l T. j\Iullfuly. B.S., See{l An[tly:-;t
*Dean of Graduate School.
tOn leav •.
The Station is located on the B. & O. R. R., City and Suburban Electric Car
Line and the Baltimore,Washington Boulevard, eight miles North
of Washington, D. C. Telephone-Warfield Exchange.
Visitors will be welcome at all times, and will be given every opportunity
to inspect the work of the Station in all its departments.
The Bulletins and Reports of the Station will be l11ailed free of charge
to all residents of the State who request them.
ADDRESS:
AGRICULTURAL EXPERIMENT STATION
COLLEGE PARK, MARYI,AND.
CONTENTS
Page
INTRODUCTION....... ........ ........... ............ ........................................ .......................... .
249
RECOMMENDATIONS FOR USE OF THIS BULLETIN.......................... ....
248
DEFINITIONS O°F A STOCK-POISONING PLANT............................................... 250
CONDITIONS OF POISONING... ............... ............ .................... ...... .... ................. ...........
250
PROCEDURES FOLLOWED IN THIS INVESTIGATION......................................
251
PLANTS WHICH HAVE CAUSED POISONING OF STOCK IN
MARYLAND AND DESCRIPTIONS OF 'rHE CASES OF POISONING................... ............ ................................................................... ... .......................................... 252
STOCK-POISONING BY PRUSSIC ACID PRODUCED IN PLANTS........
276
POISONING OF LIVE-STOCK BY FUNGL ............ '" ................ .... ...... ..............
282
PHOTOSENSITIZATION OR POISONING OF ANIMALS BY PLANT
SUBSTANCES ACTIVATED BY SUNLIGHT. ................. ................................
284
POSSIBLE STOCK-POISONING BY POTASSIUM NITRATE IN
PLANTS..... .............. ....... ............ ......... ........................................ ......................... 285
PLANTS' WHICH MAY G.i;\-USE HUMAN SKIN POISONING...................
287
MISCELLANEOUS PLANTS WHICH ARE POTENTIAL S'OURCES
OF POISONING OF LlVE-STOCK........................ ....................................................
290
TABL'E-SUMMARY O'F RECENTLY RECORDED CASES' OF PLANT
POISONING OF LWE-STOCK IN MARYLAND ....................................
311
312
INDEX............. ........ .............. ..... ... . ....... ...... .... . .............................................. 312A
ACKNOWLEDGMENTS.................................................................................................................