Joumal of Ethnopharmacology, 38 (1993) 121-128
Elsevier Scientific Publishers lreland Ltd.
121
Botanical methods in ethnopharmacology and the need for
conservation of medicinal plants
Inga Hedberg
Deparlmenl of Syslemuric Bolany. Box 541.5-75121 Uppsala (Sweden)
An imperative demand imposed on aH scientific invesligations is that they should be repeatable. which calls for adequate documen­
tation from the very beginning. In medicinal plant re~earch. botanical documenlalion plays a vital role since wilhout correctly iden­
tilied material and properly documenled voueher specimens the results are at best suspect and al worsl useless. The bolanical
eontributions requircd for ethnopharmaeologieal research thus inelude adequate naming of the material and deposition of properly
labelled voueher specimens in al leasl two public herbaria. Ethnopharmacology depends, however, upon hOlanical assistanee also
in another respeel, viz. concerning eonservalÍon. This field may seelll lo have Hule lO do with elhnopharmacology. bUl without joint
efforts to save the userul plants from extinetion, ethnopharmacology .... illlose important parts orilS main souree at an appalling raleo
Key words: documentation; herbaria; inventory; idenfification; synonymy; eonservalion
To a bolanisl 'Bolanieal melhods in elhnophar­
maeology' are so fundamenlal lhal lhey should be
well known lo all and everybody involved in
research on medicinal plants. However, a defini­
lion quoled by Sehulles (1991) indieales lhal lhis
is nol lhe case, sinee il reads: Elhnopharmaeology
has reeently been defined as 'lhe observalion, iden­
tification, description and experimental ínvestiga­
tion of lhe ingredienls and lhe effeels of
indigenous drugs'. Elhnopharmaeology is, how­
ever, a highly inlerdiseiplinary field where bolany
plays a vital role, and to leave oul lhe identifiea­
tion of planls yielding those indigenous drugs is to
leave out lhe very base for ethnopharmaeologieal
research.
Also experiences from contacts with a Swedish
medical doctor involved in a project on traditional
medicine in an African country show that much re­
mains when it comes to the planning and ac­
eomplishmenl of sueh programmes.
A furlher reason for highlighling lhe role of
bolany and botanisls in elhnopharmaeologieal
research is that recent trends within systematic
bolany ilself jeopardize fUlure availabililY of lhe
kind of botanieal expertise essential for sueh
research. In recent years molecular biology has
been given priority in several branches of biology,
lo sueh an exlenl lhal in botany il has ousled tradiCorrespondence lo: Inga Hedberg, Departmenl of Systemalic
Botany, Box 541, S·751 21 Uppsala. Sweden.
lional bolany more or less eomplelely. AII over the
world lhere is a profound lendeney lo negleel
'green botany' in favour of laboratory and com­
puter oriented activities, Field oriented, experi­
enced 'whole plant botanists' are, however, indj·
spensable for al! applied seienees dealing wilh
planls (see House of Lords 1sI Reporl,
1991-1992).
To foeus on bolany in elhnopharmacology is
badly needed also beeause bolanieal knowledge
and methodology is essential for the conservation
of medicinal plants, Though conservation is a very
important maUer the need is seldom expressed or
even touched upon at pharmacological con­
ferences. The reason míght be that conservation ís
not regarded as pure science, but on the other
hand it is vital for the future of elhnophar-'
macological research: the threat to many specíes
used for medicinal purposes is very grave and if lhe
scientists do not care about conservation, many
species might become extinct in the near future.
Discoveries of interesting substances in plant
material are of liule use if the species concerned
has in the mean time become extinct
Bolanical melhods
It is a well known fael lhat lhe evaluation of
traditional medicine varies very much depending
on whieh parl of lhe world we are dealing with.
Whereas in sorne parts, e.g. the tropics and China,
0378-8741193/$06.00 © 1993 EIsevier Scientific Publishers Ireland Ltd.
Printed and Published in Ireland
122
TABLE 1
seientifie (Latin) name al' lhe planl (if possible),
vemaeular name, loealily, part(s) al' plant used,
PROGRAM FOR STUDIES OF PLANTS IN
TRADITIONAL MEDICINE
administration, etc.
From Samuelsson (1988).
be put in a press to serve as voucher specimens for
Material al' eaeh speeies to be investigated musl
A. Tnventory and botanical identification
B. Studies of the literature
C. Pharmacological screening of extracts
D. Isolation and iden(ification of pharmacologically active
constimenrs
E. Pharmacological studies on isolated subslances
F. Toxicological studies
G. Clínical testing
H. Production of drugs
safe identifieation and future referenee. Preferably
at least two sheets should be seeured of eaeh eol­
lection to be later housed in different institutions.
In the tropies, where the material may be exposed
to serious attacks by insects and other pests, at
least three sheets must be secured. If conditions are
safe, those sheets mighl be kept in the eounlry al'
origino like in the INBIü projeel in Costa Rica
where one sheet with aH information available is
traditional medicine has always held a strong posi­
tion, lhis is nol lhe case in lhe USA or in mosl
parls of Europe. The evolulion al' modem, sehool,
medicine, in those parts meant that traditional
medicine, ineluding medicinal planls, was looked
upon wilh disregard or even eonlempt by lhe
medieal soeiely. Though lhis altilude now seems lo
be gradually ehanging il is slill wilh us, to a con­
siderable exlenl (see below).
The reawakening al' the ¡nteresl in planl
kepl in a slrong room, one goes to the INBIü her­
barium and one lo lhe university (A. Sitenfeldt,
pers. commun.). Where conditions for safe storing
of specimens are less suitable vouchers should be
kept at least in one institution in the country of
origin but also sent to institutions in temperate
regions where the risk of damage to the material is
much less. Voucher specimens must be as complete
as possible with nowers and/or fruits and, for
herbs, also roots. This is partieularly important for
lropieal malerial whieh often poses speeial dif­
substances in the industríalized countries together
ficulties
with lhe rapidly growing inlerest in developing
nowers, and bark should be taken and details on
slash, ele. given in the forms. Sinee lhe main parl
countries
to
5taft
research
prograrnmes
in
ethnopharmaeology also makes it imperative to
seeure and widen lhe knowledge about the impor­
lance of botany in such research.
The basie role played by bolany in researeh
dealing with plant substances is demonstrated in
Table l. Bul bolanieal experlise is needed nol only
for identification but a150 for inventaries and
documenfafion - aH three closely interwoven.
since inventories are meaningless and safe iden­
tification imposslble unless proper documentation
is achieved símultaneously.
in
identificatíon.
From
information from those healers is essential since
lhe possibilily al' finding aelive subslanees is mueh
greater if planls used by lhe healers are ín­
vestigaled, than if planls are sampled at random
(SpjUl and Perdue, 1978). In order to seeure pro­
per doeumenlatíon, a slandardized form (Fig. 1)
should be fiiled in for eaeh eoileetion, giving the
twigs,
of the information recorded in those forms is
essential for further pharmacological research, im­
portant details dealing with the plant from a
bolanieal poinl al' view should laler be eopied on
lhe label prepared for lhe herbarium speeimens
beeause sueh delails may be al' greal help in nam­
ing them.
Identificatian
After lhe field work has been eompleled the
mos! urgent task is the identification of the
speeimens eoileeled, whieh again
Inventaries
Lel us then slarl from lhe very beginning, lhe in­
ventories, which inelude the sorne times rather
laborious field work. This is eerlainly nol a one­
man job but leam work whieh should ideaily in­
elude al least one botanist, one elhnophar­
maeologist and local traditional healers. The
trees
makes the
availability of botanists crucial. Whereas sorne
malerial may be named without any particular dif­
ficulty, identification could in other cases be time­
consuming and sometímes very difficult.
Due lo ignoranee in this field, pea pIe, nol least
scientists, are often completely unaware of the
problems involved in this task. In Sweden, for ex­
ample, with its poor nora of aboul 1600 speeies al'
higher plants, where the famous Carl Linnaeus
started to name and elassify them more lhan 200
years ago, and where there are a number of floras
eovering lhe whole eounlry, and a 101 al' local
noras, lhere should be no diffieulties in naming
planls or planl eoileetions.
123
Oale:
Collectton SMP no.
_
1. Locallly: DisIMct
_
Village
_
Distance and direction 'rom major town,
_
Longrtude/lalrtude
Habrtal
_
2. Type 01 plant:
Tree
Herb
Parasite
Shrub
Liana
Aqueous plant
3. For Ireeo: Height & bUlk,
Bark descriplion,
_
Slash
_
4. Flower colour:
s. Frult descrlptlon:
6. Smell:
_
7, Latex present
8. Allacked by Insecto etc.:
_
_
9. Provisional tdenllflcallon:
_
10. vemacular name:
_
11. Name al lradlllonal healer:
-'­
12. Preparallon 01 remedy:
Planl part
Fresh.
_
DMed
_
Amount laken
Crushed
Cold water
_
Powdered
,Boiled
,Mixed wilh water (amount)
Bo,iling water poured over
_
_
Mixed wilh other yehiele (amount)
_
Other preparation
_
13. Dose and reglmen:
_
14. Dlsease or symptoms treated:
15. Plant used together wlth the 101l0wlng plants: (VemaQJlar name or SMP-number. Part 01 plant.
Note amount 01 plant part laken in preparation or other delails it preparation differs trom descriplion in
12 aboYe).
17. Addlllonal nOles:
Fig. 1. Fonn suggested for lield inventories in ethnopharmacological res¡;:arch (Samuelsson et al.. 1991 l.
124
TABLE 2
EXAMPLES OF THE USE OF THE SAME VERNACULAR NAME FOR D1FFERENT SPEC1ES
Extracted from Kokwaro (1976).
Language
Vernacular name
Scientilic name
Family
Digo
Kibombo
DissUlis rolUndifolia
Rauvo(fia mombllsillnll
Melastomataceae
Apm;ynaceae
Digo
Kamata
Aerangis thomsonii
Culcasia scandens
Orchidaceae
Araceae
Kamba
Kawala
Rubia cordifolia
5wpefia semora
Rubiaceae
AsclepiaJaceae
Kipsigis
Lemeiywet
Ozoroa incano
Syzygium guineen5e
Anacardiaceae
Myrtaceae
Cardiogyne africana
Cissus rotundifolia
Moraceae
Vitaceae
Ngoni
Mambahuru
In tropical countries, e.g. Tanzania or Colom­
bia, with about 10000 and 30000 species, respec­
tively. \""ith a considerable number unknown lo
science. and with floras covering only a portion of
the plan! families, !he situation becomes vastly dif­
feren!. The naming of a specimen in the ¡ield quite
often offers considerable difficulties or is impossi­
ble. In such cases the vernacular name may be used
as a reference, to be later replaced by the scientitic
name. It is then extremely important to be aware
of the fac! !ha! the same vernacular name
sometimes is applied to different species, as ex­
emplitied in Table 2, which shows that the same
vernacular name may refer to species from fairly
distanUy related families. Differences in pronun­
ciation may sometimes reveal to which species
reference is made, but sueh a difference will ob­
viously not be traceable from a \\-Titten formo
On the other hand, different vernacular na mes
are sometimes used for the same species as shown
in Table 3. If a voucher specimen is not available
this might cause considerable confusion.
TABLE 3
EXAMPLES OF THE USE OF DlFFERENT
VERNACULAR NAMES FOR THE SAME SPECtES
Language
Vernacular
name
Scientific
name
Family
Digo
Mungwene
MS<:l];msi
Ul'ario aClJminala
Annonaceac
Shambaa
Mnkande
Mvugve
Mvungunya
Kigdia africana
8ignoniaceae
Digo
Mserere
Mseltettc
Mtambaajongoo
Mvuma
Hoslundia oppmi((J.
Labiatae
Shambaa
Mshwee
Mshwelelc
125
TABLE 4
LIST OF SYNONYMS FOR COMBRETUM COLLlNUM
FRESEN.
Combretum abercornense Exell
e u/hum De Wild.
C. angustilancevlulum EngL
C. bajonense Sim
C. binderanum Kotschy
C. brosigianum Engl. & Die!:;
C. burllú Exell
e
elaeagnlfolium Olivo
C. elgonense Exell
C. sr. near C. elgonense sensu Burtt Davy
C. fischeri Engl.
C. jlaviflorum Exell
? C. frommjj Engl.
C. gazense Swynn. & Bale r.
e goerzenianum Die1s
C. hypopilinum Diels
e kabadense Exell
C. karaguense Engl. & Diels
? C. kerengense Diels
C. kotloense Exell
C. laboniense M.B. Moss
C. makindense Engl.
e. mechowianum O.
HotTm. subsp. ga::ense (Swynn. & Bak.f.)
Duvign.
C. mechowianum O. HofTm. subsp. taborense (Engl.) Duvign.
C. mwanzense Exell
? C. oliveranwn Engl.
e. populifolium EngL & Diels
C. psammophilum Engl. & Diels
e
e
e
e
?
e
ritschardii De Wild. & Exell
singidense Ellel1
suluense Engl. & Diels
taborense Engl.
trllncalum Engl.
verlicillacum Engl.
e
and that lhe material broughl home was worked
up without sufficient contact between botanists
from differenl countries, partly because the
material available was too scarce to reveal the con­
tinuous variation that often existed. Thus for
many species a number of synonyms have ac­
cumulated, the amount of which may sometimes
be rather impressive. as shown in Tables 4 and 5.
In the case of Combretum col/inum 30 synonyms
have been listed, aH under the generic name Com­
bretum. For Maytenus helerophylla no less than 42
synonyms are listed, only three of which are given
TABLE 5
L1ST OF SYNONYMS FOR MA YTENUS
HETEROPHYLLA (ECKL. & ZEYH.) N.ROBS.
Cassine s;;yszylowiczii Kuntze
Ca/ha buxifolia (L.) G. Don
e. cymosa (Soland.) C. Presl.
C. heterophylla (Eckl. & Zeyh.) Presl.
Celaslrus andongensis Olivo
angularü Sondo
e. buxifolius L.
C. cymosus Solando
elliplicus Thunb.
empleurifolius &kl. & Zeyh.
C. goniecaulis &kl. & Zeyh.
C. helerophy/lus Eckl. & Zeyh.
C. humi/ü Eckl. & Zeyh.
C. multiflorus Lam.
parvifolius Eck.l. & Zeyh.
palens Eckl. & Zcyh.
C. polyacanfhus sensu Eyles
C. polyan/hemos Eckl. & Zeyh.
rhombifolius Eck,1. & Zeyh.
spathephyllus &kI. & Zeyh.
C. venenafus Eckl. & Zeyh.
Elaeodendron glaucum semu Szyszyl
Gymnosporia acanthophora Loes.
G. angularis (Sond.) Sim.
G. brevipetala Loes.
G. buxifolia (L.) Szyszyl.
G. buxifolioides Loes.
G. capitata var. fenuifolia Loes.
G. condensala Sprague
G. cracaegiflora Davison
G. elliptica (Thunb.) Sehon!.
G. glauca Loes.
G. heterophylla (&kl. & Zeyh.) Loes.
G. maranguensÍ5 (Loes.) Loes
G. rhombifolia (Eckl). & Zeyh.) Bolus & Wolley-Dod
G. senegalensis vaL marangllPnsú Loes.
Gymnosporia trigyna sensu Perrier
G. uniflora Davison
G. woodii SzyszyJ
Maytenlls angalensis Ellell & Mendonp¡
M. bre~ipetala (Loes.) Wilczek
M. cymosa (Soland.) Ellell
e
e
e
e
e
e
e
For definite naming it is also in many cases
necessary to compare the voucher to adequately
named material in a large herbarium.
Synonymy
Because of lhe very long hislory of the use of
medicinal planls and lhe comparatively shor!
hislory of lhe scientific study of such plants we are
to-day facing a serious lack of routines in various
respects. The securing of vouchers has been - or
is - one, the necessity to find out and use the cor­
rect scientific name is another. Botanical revisions
of various plant families or groups often reveal
lhat a widespread tropical species has been
described by differenl botanisls under different
names. This is partly because collecting expedi­
tions in earlier days were organised by a number
of European countries in their respective colonies
126
under the generic name MaJ'tenus, the others
under 6 other generíc names.
The establishing and handling of such synonym
lists may be very time-consuming, but unless full
synonyíny is given. tedious and expensive analyses
and tests might be unnecessarily repeated In
species which have already been subjected to
led from a planllhat was idenlified only as 'prob­
ably belonging lo the Menispermaceae!'.
1t goes without saying that investigations car­
ried oul on material nol properly idenlified and
documented are of HUle if any use, since it is im­
possible lo know wilh cerlainty lhe source of lhe
chemical compound.
detailed investigations under a different species
name.
To sum up: For successful inventories and utiliza­
Documentation
lion of planls in elhnopharmacological research
lhe following precautions musl he taken:
Another focal point in elhnopharmacology is
the need foc documentation, an aspect which has
been badly neglected in far too many invesliga­
lions. Striking examples are given by Farnsworth
and Morris (1976) of very expensive and elaborale
research turning oul lo be complelely wasted
because of inadequate documentation.
An imperative demand on every scientific inves­
ligalion is that il should be repeatable, and one of
the most difficult problems in research on medici­
•
To secure good voucher specimens. in
temperate regions at least two sets, in the
lropics al leasl lhree. properly documenled
wilh collector, colleclion number and localily.
This information must be glven in each report
together with references to herbaria where
vouchers are deposited.
• To give, in standardized form, information on
locality, habitat, use. administration, etc., thus
material aften gives discordant results compared
making it possible lo re-collecl lhe species and
lo use lhe inforenalion given by traditional
wilh the first analyses. This may in sorne cases be
healers.
nal planls is lhal analysis from a second balch of
due to variatíon [rom Dile 101 to another in the
concenlration of aclive substances, but is probably
more often due lo lhe fact thal lhe second sample
was taken rrom a difIerent species. Such failures
For a satisfactory organisation of ethnophar­
macologicaJ research - and for lhal malter also
on all olher planl relaled projecls - the bolanical
can only be avoided if documenting colleclions
with complete voucher specimens are secured of aH
infrastructure requíred is:
plants investigated and infonnation on these
vouchers is published with each report on active
substances. The inclusion in every report of infor­
• A well equipped herharium where specimens
can be named and vouchers kepl for indefinile
periods.
• A well lrained herbarium slaff, lo handIe the
colleclions and prevent lhem from being
deslroyed by insecls or olher pesls.
• Scienlifically lrained botanisls capable of
dealing wilh the naming, checking of
malion on lhe planl malerial used - collector, col­
lection number and lhe herbarium in which lhe
vouchers are housed - offers lhe only possibilily
of checking the identily of a planl and making sure
that the same species is investigated on a later oc­
casion.
The ex.treme importance of vouchers should
thus be obvious to every scientist, and according
to recent information no reputable journal wouJd
accept a paper for publicalion if lhis inforenalion
is missing. Bul only about 15 years ago Farns­
worlh and Bingel (1977) reported lhe following
from a survey of lhe 1975 lilerature dealing wilh
lhe isolation of new chemical entilies from higher
planls: 'Gnly 160 of the 2399 novel chemical com­
pounds reporled were isolaled from planls for
which the aulhor(s) indicaled lhal a voucher speci­
men was available for reference to the plant mate­
rial invesligaled. There is even a 1975 paper,
published in a repulable chemical journal, in
which a new compound was reported to be isola­
synonyms, etc.
• A well equipped library wilh floras and olher
lileralure lo make il possible for bolanisls lo
name specímens belonging to families or
groups with which lhey are nol familiar.
Only if those resources are available can
elhnopharenacological research on planls be suc­
cessfully carried out.
Conservation of medicinal plants
Al firsl sighl ethnopharrnacological research
may seem to have httle to do with conservation of
medicinal plants. Bringing lhis up al a congress
otherwise slrictly devoled lo ethnopharenacology
t27
makes me recall Calo lhe elder (234-149 B.C.),
who - regardless of lhe subjecl he was lalking
aboul - is reporled always lo have finished his
speech with the words: 'praetera censeo Car­
thaginem esse delendam', Le. 'besides. rny apioian
is lhal Carlhage musl be deslroyed'. Bul whereas
many times Cato's remark was completely ¡rrele­
vant in relation lo the subject treated, rny message
should be cornmunicated al each conference deal­
ing with plant material lo remind scientists not
only of lhe vulnerabililY of much of lheir research
malerial bul also of lhe need for urgenl aclion. The
subject has in recent years beeo touched upon al
several conferences and in a number of publica­
lions, e.g. Hedberg (1987), Maheswari (1988),
Akerele el al. (1991), bUl il seems as mosl of lhe
appeals for aclion are eilher like preaching lo
lhose already converted or falling lo deaf ears. If
we - as again pointed out al a recent conference
00 'Systematics and conservation evaluation' ­
are going lo witness a mass extinction of medicinal
planls in lhe nexl few decades, lhis will be a
calaslrophy for people in lhe developing counlries,
where al presenl aboul 80% of lhe populalion de­
pend on lradilional medicine. lt would also be
disastrous for ethnopharmacologists. ror science
as a whole, and for humankind, not least since
only a fraclion of all higher planl species have
been properly investigaled (Farnsworlh and Soe­
jarto, 1991).
Obviously, elhnopharmacologislS like all olher
scientists working in basic or applied sciences deal­
ing wilh planls, have a heavy responsibilily lo help
save as much as possible of botanical biodiversity.
But to get the message across in such a way that
il really has an effect seems lo be eXlremely dif­
ficult, not least because scientists either are not in­
terested in communicating with society or lack the
ability lo do so. This problem has been treated by
Wachlel (1991) in a paper with lhe significant tille
'Lel's slop talking lo ourselves: the need for public
awareness'. Such a call certainly requires a more
broad-minded approach lhan is usually demon­
strated by representatives of our modern scientific
community.
There is probably nothing wrong in glorifying
the advances made in modern medicine during the
last few decades but this should cerlainly nol be
done by concealing al the same time the fact that
much of to-day's medicine is founded on ex­
periences and knowledge inheriled from earlier
days and from many years of research on planls.
Lel us go back 10 the introductory remark on
the approach to traditional medicine in our part of
Take llllle
live
ants
•
f
\..
From tbe belief of yesterday
to the knowledge oC to-day.
Fig. 2. Pamphlet on modern medicines issued by the National
Corporation of Swedish Pharmacies and published by their
permission. (Tcxt translated by lhe author.)
lhe world and see how il was lrealed only a few
years ago (Fig. 2). The pamphlel was issued by lhe
Nationa! Corporation of Swedish Pharmacies and
avadable in all pharmacies in Sweden.
Even if the pamphlel was intended in lhe first
place lo give information abolll lo-day's phar­
maceulics il is difficult lo undersland why lhis had
to be done in a way that immediately throws an air
ofridicule over what in fact has been extremely ¡m­
portant for the success of pharmacological re­
search. One might well ask why such an absurd
example from traditíonal medicine was chosen.
In a pamphlet like this, wouldn'l il have been
appropriale lo acknowledge the immense impor­
tance of the use of plants in medicine, taking into
account lhat 25-30';;0 of all western medicines slill
are derived directly or indirectly from higher
plants, that a large amount of our medicines to­
day have been synthesized using naturally occurr­
ing substances in plants as a model, and that - in
spite of great efforls over many years - it has still
128
proved impossible to synthesíze a considerable
number of active substances used in to-day's
medicine.
There seems al50 lo be an unfortunate and pro­
nounced tendency amongst scientists trying to de­
sigo vacious compounds to forget oc ¡eave out that
they often use nalural producls as models for their
synlheses. In lhis way lhe fundamenlal role played
by plants in such research remains unknown to tbe
media and consequenlly also lo lhe general public.
This lendency has lo be counteracled bul il ap­
pears lhat up to now elhnopharmacologisls have
been less apl actívely lo challenge lhe dislortion
caused by sorne recent trends in phannacological
research. It is obviously high lime aClively lo draw
lhe attentíon of sociely lo lhe role of elhnophar­
macology in lhe development of pharmacculics.
Iike
those
of
Unfortunalely,
slatemenls
Mangelsdorf in 1972. correcting his 1941 predic­
lion lhal in anolher 25 years drugs of plant origin
would be of little more lhan hislorical inleresl, or
publicalions Iike lhal by Farnsworth and Morris
(1976): 'Higher planls - lhe sleeping gianl of drug
development' do nol reach those who in lhe flrsl
place should be informed.
A policy musl be worked oul lo make the value
of plants c1early visible lo decision makers and lhe
general publico This could be done by joining
forces wilh bolanists, i.e. whole planl bolanisls,
and conservationists, thus safeguarding the condi­
tions for ethnopharmacological research. This
would also draw attention lo the value of tradi­
lional knowledge and assist in the conservation of
this knowledge and lhe planls which may be vital
ror OUT survival.
References
Akcrele. O., Heywood, Y. and Synge, H. (Eds.) (1991) Conscr­
\'aliOTl of Medicinal Plarlts. Cambridge Uoiversity Press,
Cambridge
Famsworth, N.R, and Bingel, A.S. (1977) Problems and pro­
spects of discovering new drugs from higher plants by phar·
macological screening. In: H. Wagner and P, Wolff (Eds.),
Medicinal Plam Research. Springer Verlag, Berlin, pp. 1-22.
Farnsworth, N.R. and Morris, R.W. ([976) Higher plants -­
the sleeping giant of drug development. American Joumal of
Pharmacy 148, 46-52.
Farnsworth, N.R. and Soejarto, D.D. (1991) Global impor­
tance of medicínal plants. ln: O. Akerele, V. Heywood and
H. Synge (Eds.), Consen'alíon oJ Medicinal Plan/s. Cam­
bridge University Press, Cambridge, pp. 25-42.
Hedberg, l. (1987) Research on medicinal and poisonous p1ants
in the tropics: past, present and future. In: AJ.M.
Leeuwenberg (Compiler), Medicinal and Poi.!onous Plants oJ
lhe TropicJ. Pudoc, Wageningen, pp. 9-15.
House of Lords 1st Report, Session 1991-92, Syslemalic Bio·
/ogy Research, Vol. l. (HL Paper 22-1). HMSO, London.
Kokwaro, 1.0. 1976, Medicinal Planrs oJ Easl A.frica. East
African Literature Burcau, Nairobi.
Maheshwari, J.K. (198&) Ethnobotanical research and
documentation. In: 1. Hedberg (Ed.), Systematic Botany­
a key science for tropical research and documenlation. Sym­
bo/ae Bolanicae Upsalienses 2& (3), 207-217.
Mangelsdorf, P.e. (1972) Introduction. In; T. Swain (Ed.l.
Plants in lhe Developmenl ofModem Medicine. Harvard Uni­
versity Press, Cambridge, MA.
Samuelsson. o. (1988) The need for systematic botany in re­
search on planls used in [radilional medicine. [n: 1. Hedberg
(Ed.), Systematic botany - a key science for tropical re­
search and documentation. Symbo/ae Bofanicae Upsaliensis
28 (Jj. 186-188.
Samuelsson, 0., Farah. M.H .. Claeson, P.. Hagos, M .• Thulin.
M., Hedberg, O., Warfa, A.M., Hassan, A.O., Elmi. A.H.,
Abdurahman. A.D .• Elmi, A.S .. Abdí. Y.A. and Alín, M.H.
(1991) Inventory of plants used in traditional medicine in
Somalia. 1. Plants of the families Acanthaceae-Chenopod­
iaceae. Jouma! of Elhnophormac%gy 35. 25-63.
Schultes, R.E. (1991) The reason for ethnobotanícal conserva­
tion. In: O. Akerele, V. Heywood and H. Synge, (Eds.l. Thc
Conservation of Medicinal Pfants. Cambridge Univcrsity
Press, Cambridge. pp. 65-75.
Spjut, R.W. and Perdue, R.E. (1978) Plant folklore: a tool for
predicting sources of antitumour ac,ivities? Cancer Treal­
menl Reporfs 60, 979-985.
Wachtel, P. (1991) Lel's stop talking to ourselves: the need for
public awareness. In: O. Akerele. V. Heywood. and H. Synge
(Eds.). Consenalion of Medicinal Planls. Cambridge Uníver­
sity Press, Cambridge, pp. 273-280.