Amer. J. Bot. 63(10):
1302-1310. 1976.
STUDIES OF PALEOZOIC SEED FERNS: ANATOMY AND
MORPHOLOGY OF MICROSPERMOPTERIS APHYLLUM1
THOMAS N. TAYLOR AND RUTH A. STOCKEY
Columbus43210
Departmentof Botany,The Ohio State University,
A B S T R A C T
genusMicrospermopThe discoveryof numerousspecimensof the monostelicpteridosperm
fromthe Lewis Creek and What Cheer localities
coal ball petrifactions
teris in Pennsylvanian
about the anatomicaland morphologicalvariabilitywithin
providesadditionalinformation
thegenus. Specimensare now knownup to 1.1 cm in diam thatbear epidermalappendagesin
ornamented
trichomes.The externalsurfaceof thestemis further
theformof variously-shaped
a singleC-shapedvascularstrand
flapsof corticaltissue. Petiolesexhibiting
by longitudinal
are producedin a 2/5 phyllotaxy.Large petiole bases that clasp
withabaxial protoxylem
thestemproduceprimarypinnaealternately.The presenceof axillarybranchingappearssimiroots,
lar to thatreportedin Callistophytonand Lyginopteris. Triarchto polyarchadventitious
some withsecondarytissues,are producedat both nodal and internodalregions.Of the currentlyrecognizedmonostelicseed ferngenera,Microspermopteris is most similarto Heteris presentedthatsupportscurrentideas regardingthe evolutionof the
angium. Information
eustelefromprotostelicDevonian ancestors.
gymnospermic
initiallydemascribedby Baxter (1949) frompetrifaction
terial collectedfromthe What Cheer locality of
Iowa, witha subsequentvarietyadded frommaterialcollectedfromthe FlemingCoal of Kansas
(Baxter, 1952). Recently,the taxon has been
reportedfromseveral coals in Illinois (Mahaffy,
1975) and easternKentucky(Taylor and Stockey, 1975). In the initialdescriptionthe genus
with
was characterizedas a leaflesspteridosperm
an exarch, partiallymixed protosteleup to 5.0
mm in diam. Stems were describedas being irregularin outlineand lackingleaves. Multicellular emergencestogetherwith adventitiousroots
were described on some stem fragments.The
genus was furthercharacterizedby the presence
of secondary tissues, concentricbranch traces,
and distichousbranching.
Duringthe past severalyearswe have accumulated a numberof specimensof this plant from
two petrifactionlocalities in North America,
especiallythe Lewis Creek site in easternKentuckywhere it representsa common elementof
the flora. It is our intentin thispaper to provide
additional informationabout this taxon, offera
of severalmorphologicalfeatures,
reinterpretation
in light
and discuss the genus Microspermopteris
of recenttheoriesregardingthe evolutionof the
habit.
gymnospermous
The followingdescriptionis based upon 36
THE GENUS MICROSPERMOPTERISwas
axes representing
numerousordersof branching.
Specimens were collected fromthe What Cheer
and Lewis Creek petrifactionlocalities which
are designatedMiddle and Early Pennsylvanian,
respectively(Good, 1975). Cellulose acetate
peels were used to determineanatomical and
morphologicalfeatures.All specimensand slides
are housed in the PaleobotanicalCollections,Departmentof Botany, The Ohio State University,
and include acquisition numbers 6,489-6,912,
12,177-12,420, 12,422-12,466.
DIAGNOSIs-Microspermopteris
aphyllum(Baxter) Taylor et Stockeyemend. Stems up to 1.1
cm in diam withmixed exarchprotosteleconsisting of large metaxylemtracheidsand up, to 10
peripherallypositionedprotoxylemstrands. Petioles arranged in 2/5 phyllotaxy,with single
trace slightlyC-shaped with abaxial protoxylem;
petiole base large and clasping up to one half
stem circumference,primary pinnae produced
alternately;axillarybrancheswith abundantsecondaryxylem. Cortexof thin-walledparenchyma
with secretorycells in youngerstems, and peripherally disposed longitudinal sclerenchyma;
peridermof thick-walledradially aligned cells.
Stem surface ornamentedby longitudinalflaps
of corticaltissue,and multicellular,
typicallyflattened trichomes. Metaxylemtracheidselongate,
with multiseriatebordered pits; protoxylemelementsscalariform.Primaryxylempentagonalin
cross sectionand divided into 5 sectionsby lon'Received for publication17 December 1975.
The authorsare indebtedto Dr. JohnW. Hall for gitudinal parenchymaplates that radiate from
making several What Cheer specimensavailable for stem center; protoxylemstrandsoccur in pairs,
study,and to the National Science Foundationfor parone strandon each side of a parenchymaplate.
tial supportof this research(BMS74-21105).
1302
November-December,
1976]
TAYLOR AND STOCKEY-MORPHOLOGY
OF MICROSPERMOPTERIS
1303
Secondary vascular tissues well-developed,sec- trace has been formedit remainswithinthe stem
ondaryxylemtracheidswithuni- and multiseriate cortexforsome distance(approximately6.0 mm)
bordered pits. Xylem rays up to 2 cells wide. beforepassing outwardinto the petiole base.
Triarchto polyarchadventitiousroots,some with
The most conspicuousaspect of the cross secsecondarytissues,arisingat both nodal and inter- tional configuration
is the
of Microspermopteris
nodal regions.
presence of large, angular metaxylemtracheids
(Fig. 1). In longitudinalsection,metaxylemeleType species- Microspermopterisaphyllum mentsmeasureup to 1.0 mm and possess slightly
Baxter 1949, p. 297-298, pl. 2, Fig. 1-4; pl. 3, tapered end walls, and multiseriate,
simple-reticFig. 5-7; pl. 4, Fig. 8-12.
ulate-bordered
pits (Fig. 19). Parenchymain the
metaxylemis organized into longitudinalplates
Synonymy-1952. Microspermopterisaphyl- up to threecells wide thatradiatefromthe center
lum var. kansensisBaxter; Trans. Kansas Acad. of the stemto formthe characteristic
pentagonal
Sci. 55: 101-103.
stem configuration(Fig. 4). We have observed
a largernumberof platesin some stems;however,
DESCRIPTION-General features-Stems range in all instancesthis increasein numberof plates
from0.5-11.0 mm in diam, withthe most com- appears to have resultedfromadditionaldivisions
plete specimenextendingapproximately38.0 cm of the originalfiveplates (Fig. 1).
throughthe coal ball. Most stems exhibit a
sinuous habit in the matrixmakinglongitudinal Axillary branching-One of the newly interstem sectionsdifficult
to obtain and possiblyre- pretedfeaturesof Microspermopteris
is the presflectinga liana or shrub-likegrowthhabit. A ence of axillarybranching(Fig. 24). Figures 12pentagonal protostele containing longitudinal 14, 17-18 illustrateprogressivestages of stem
plates of parenchyma(Fig. 1, 4, 15) is sur- and petioleseparation,and axillarybranchorigin.
roundedby a well-developedzone of secondary The productionof an axillarybranchbeginswith
xylem. To the outsideof thistissueis a vascular a large amount of secondary xylem extending
cambium, a zone of secondaryphloem, and a laterallyfrom the stem stele (Fig. 13). At a
parenchymatouscortex containing patches of slightlyhigherlevel (Fig. 12, 14) it becomes
sclerenchymaand secretorycells (Fig. 1, 4, 7, separatedto forma tereteaxillarybranch stele.
11, 16). Multicellulartrichomesand longitudinal Figure 17 representsthe axillarybranch, traced
corticalflaps extendfromthe stem surface(Fig. for a distanceof approximately5.3 mm. In this
2, 5, 8, 9, 25).
specimenthe moredistalorganizationof the axillary branch could not be determinedbecause of
Primarytissues-In transversesectionthe pri- faultypreservation.In tranversesectionthe axilmaryxylemis typicallypentagonalin outline as lary branchstele is circularwitha centralregion
definedby radiatingparenchymaplates (Fig. 1, of smallcrushedcells possiblyrepresenting
proto4). At themoredistallevelsof the stemthiscon- xylemelementsor parenchyma,surroundedby a
figuration
is maintainedby clustersof metaxylem zone of up to 12 rows of secondaryxylemtratracheids separated by patches of parenchyma cheids. At the point of axillary branch origin
(Fig. 7). In the stemthatcontainsthe mostsec- thereis a distinctinterruption
in the secondary
ondary xylem (Fig. 4) (Lewis Creek) the pri- xylem of the stem stele (Fig. 17, 18, arrows).
maryxylemmeasures 1.1 mm in cross sectional At higherlevels a few files of secondaryxylem
diam,whereasthe stemillustrated
in Fig. 1 (What tracheidsare present.
Cheer) has approximatelyone-thirdthe secondary tissuedevelopmentand the primaryxylemis
Petiole-The petiole or rachis clasps the stem
1.7 mm in diam. The stem illustratedin Fig. 7 axis for approximatelyone half of the diameter
is representedalmostentirelyby primarytissues. of the stemat the level of axillarybranchformaThe protoxylem strands in Microspermop- tion (Fig. 12, 24). At higherlevels the cross
teris,as determinedby cell diameterand pres- sectionalconfiguration
of the petiole is V-shaped
ence of annular-scalariform
wall thickenings,
are to almost flattened(Fig. 17, 21). In several
situatedon eitherside of the parenchymaplates specimens it has been possible to trace alterthat radiatefromthe stemcenter(Fig. 3). Fig- natelyarrangedprimarypinna axes (Fig. 20-22).
ures 3, 6, and 10 illustratesuccessivelyhigher The pinna trace consists of a single lateral xylevels throughprotoxylemstrandsin a regionof lary extensionthat shows the same anatomical
organizationas the
trace. Two longitutrace emission. In Fig. 3 the arrows on either dinal extensions petiole
of tissue ornamentthe adaxial
side of the metaxylemparenchymaindicate the surfaceof the petiolenear thelevel of pinna trace
small protoxylemstrands. At a slightlyhigher formation(Fig. 21-22). It has not been poslevel (Fig. 12) the 2 strandsunite to forman sible to demonstrateconclusivelymore than a
abaxial C-shaped bundle containinga circular singleorderof petiole branchingor the presence
strand of large metaxylemtracheids. Afterthe oflaminarpinnules.
1304
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TAYLOR AND STOCKEY-MORPHOLOGY
Secondary tissues-In almost all of the stems
examined there is evidence of some secondary
development.In older stems (Fig. 4) secondary
xylem consists of radially aligned tracheidsinterspersedwith vascular rays. Wood segments
varyfrom1-4 cells wide withthe individualtracheidssquare to rectangular
in outline. Tracheids
in the secondaryxylem are approximatelyone
eighththe cross sectionaldiam of the metaxylem
elements. Pittingis similarto that found on the
metaxylemtracheids. Bordered pits are also
presenton the radial walls of secondaryxylem
tracheids,but typicallylack a regular arrangement. Xylary rays are constructedof procumbent parenchymathat is organizedin both uniseriate and biseriate files. A narrow, poorly
preservedcambial zone is presentto the outside
of the secondaryxylem(Fig. 1, 16).
Small, rectangularsieve cells up to 25 /m in
diam and phloemparenchymaconstitutethe zone
of secondary phloem (Fig. 11). The smaller
phloem parenchymacells are organized in tangential chains of 2-5 cells that alternatewith
largercells, presumedto be sieve elements. This
is similarto what has been describedin Callistophyton(Rothwell, 1975). In the stemillustrated
in Fig. 11 this regionis approximately0.3 mm
thick. Preservationdoes not allow for the positive identificationof sieve areas. Phloem rays
show some increase in widthtowardthe periphery of the stem (Fig. 11). Parenchymaof the
phloemraysis identicalto the parenchymaof the
platesin themetaxylem.
Several stemsshow distinctdifferences
in symmetry(Fig. 4). This featureis quite noticeable
in relativelymature stems with extensivelydeveloped secondaryxylem,and appears to be the
result of gaps formed in the secondary xylem
when branchesare produced (Fig. 4, 17, 18).
OF MICROSPERMOPTERIS
1305
Baxter (1949) in the initialwork on the genus,
aligned scleroticcells.
nor a zone of tangentially
Vertically aligned mucilage cells are scattered
among the parenchymaof the cortex of some
stems (Fig. 7). The presence of these cells, as
well as the tangentiallyorientedscleroticfibers,
appears to depend upon the age of the stem,degree of preservation,and level of section. In
some stemsa well-developedperidermis present
withinthe cortex. It consists of up to several
rows of radiallyaligned cells that probablyconstitutethephelloderm,and an outer,thinnerzone
of thick-walled
cells of the phellem(Fig. 16).
Longitudinallateral extensionsof the cortex
give the more distal stems a wing-likeappearance (Fig. 2, 7, 23). These lateral extensions
lack a distinctmorphologyand reflectthe irregular outline of the cortex. In addition to these
multicorticalflaps, thereare irregularly-shaped
cellular trichomes(Fig. 5, 8, 9). They may be
sharplytapered(Fig. 9), or clusteredinto several
projectionsthat arise froma common,
finger-like
expanded base (Fig. 5). These structuresare
presentat all levels of the stems (Fig. 25), but
appear to be morecommonalong the distalparts
of axes, and at nodes. These structuresdo, not
appear to have been producedin any orderlyarrangement.
Roots-Triarch to polyarchadventitiousroots,
some showingwell developed secondarytissues
are presentat all levels along the stems except
on distal axes (Fig. 25). Roots are presentat
both nodal and internodallevels. Many branch
the coal
and displaya sinuouscourse throughout
ball similar to that exhibitedby small stems.
Older roots may be distinguishedfromyounger
stemswithsmall amountsof secondaryxylemby
the absence of radial parenchymaplates. Both
exhibitprominentmucilageductsin an irregularly
shapedcortex.
Cortex-The cortexis irregularin outlineand
is constructedof thin-walledcells. Toward the
peripheryof the stem the corticalcells decrease
DISCUSSION-There are a numberof so-called
in diameterand possess slightlythickerwalls. We monostelicseed ferns to which Microspermophave not been able to distinguish
withany degree terismaybe compared. These includethe genera
of regularitythe two-partedcortex reportedby Stenomyelon,
SchopCallistophyton,
Lyginopteris,
body,wellaphyllum. 1. Transversesectionof stemshowingpentagonalprimary
Fig. 1-10. Microspermopteris
tissues. Arrows indicatepositionsof departingpetiole traces. C.B.
developedsecondaryxylem,and extraxylary
1298 B (1)1(2) #10. x 16. 2. Transversesectionof stemshowingirregularoutlineand numerouscorticalprojections. C.B. 198A, #106. X 25. 3. Section showingformationof petiole trace. Arrowsindicatepositionof
protoxylemelements. Larger cells representmetaxylemtracheids.C.B. 6057 C top, #123 ,B. X 95. 4. Transof primary
body. C.B.
verse sectionof stem with well-developedsecondaryxylem. Note pentagonalconfiguration
6057 C top, #123 3. X 16. 5. Transversesectionof stemshowingcorticalprojections.C.B. 198A, #106. X 100.
higherlevel than that of Fig. 3. Arrowsindicatepositionof protoxylem
6. Formationof petioletraceat slightly
tracheids.C.B. 1298 B(1)1(2), #5. X 95. 7. Transversesectionof young axis showingsecretorycavitiesin
cortexand irregularstemoutline. Note small amountof secondaryxylem.C.B. 1061 B bot, #3. x 24. 8. Transtrichome.C.B. 198A side, #30. X 100. 9. Longitudinalsectionof multicellular
verse sectionof multicellular
higherlevel thanFig.
trichome.C.B. 198A side, #30. x 100. 10. Transversesectionof petioletrace at slightly
elements.C.B. 1298 B(1)1(2), #5. X 95. pp, parenchymaplate.
6. Arrowsindicatethe positionof protoxylem
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TAYLOR AND STOCKEY-MORPHOLOGY
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1307
t'
Fig. 20-22. Microspermopteris
aphyllum. Successiveseriesshowingdepartureof primarypinnae. 20. Depart-
ing pinna trace still within petiole cortex. C.B. 6057 C top, #91. X 17. 21. Higherlevel than Fig. 20 showing
primarypinna almost separatedfrompetiole. Note the flattenedconfiguration
of the pinna axis. C.B. 6057 C
top, #123 P. X 47. 22. Still higherlevel showingpinna separatedfrompetiole,and initiationof new trace from
oppositeside of petiole. C.B. 6057 C top. #146 ,p. X 17. Arrow in each figure depicts primary pinna axis from
lower level. PT, petiole trace; PPT, primarypinna trace.
fiastrum,Rhetinangium,
Calamopitys,and Heterangium. Of these the genus Heterangiumshows
the closest affinityto Microspermopteriswhen
only featuresof the stele are considered.
Specimens of Heterangiumare relativelyrare
in North American petrifactionmaterial. Graham (1935), and Fisher and Noe (1938) reportedthe occurrenceof the genus in coal balls
fromthe Illinois Basin, while Andrews ( 1942)
detailed the stelar anatomyof a new species, H.
americanum. The recent study by Shadle and
Stidd (1975) has expandedour knowledgeof the
rachial anatomyand pinnule organizationof the
Heterangium
frond.
Stemsof Heterangiumextendup to 5.0 cm in
diam and are characterizedby irregularbranch-
Fig. 11-19. Microspermopteris
aphyllum. 11. Transversesectionshowingextraxylary
tissues.C.B. 1298 B(1)1(1)
bot, #2. X 100. 12. Transversesectionat level wherestem,axillarybranch,and petioleare attached.Note interruptionproducedin stemsecondaryxylemnear pointof branch departure.C.B. 198 B bot, #226. x 15. 13.
Sectionof stembelow thatof Fig. 12 just afterpetioletrace departure.C.B. 198 B bot, #313. X 15. 14. Transverse sectionslightlyhigherthan Fig. 12 in whichpetiolehas separatedfromstem. Note claspingC-shapedconfiguration
of petiole. C.B. 198 B bot,#205. X 15. 15. Radial sectionof metaxylemshowinglongitudinalorganiztion of parenchyma
plate. C.B. 6000 I side, #214, x 110. 16. Transversesectionof stemshowingperidermand
of cortex. C.B. 1298 B(1)I(2) #10. x 95. 17. Transversesectionat level higherthanFig. 14 with
sclerenchyma
axillarybranchalmostseparatedfromstem. Axillarybranchsteleis missing.C.B. 198 B bot, #157. x 15. 18.
Transversesectionconsiderablyhigherthan Fig. 17 showingrelationship
betweenstem and petiole. C.B. 198 B
bot, #95. X 15. 19. Circular borderedpits of metaxylemtracheid. C.B. 198 A side, #47. x 180. AB,
axillarybranch;P, periderm;PP, parenchymaplate; PR, phloemray; PT, petioletrace;S, stem;SC, sclerenchymatous cortex;SP, secondaryphloem.
1308
AMERICAN
JOURNAL
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j
63
)K
W
-4
ste morpholog[
reonstructionshowing
Suggested
Fig. 23-25.
epidermal
aphyllum. 23. Stem segment showing irregular outline of cortex and flattened
Microspermopteris
petiole. 25.
rorign of axillarv branch. Note claspDing
of ste-m at nodep showingr
Segment
24.
trcoms
November-December,
1976]
TAYLOR AND STOCKEY-MORPHOLOGY
OF MICROSPERMOPTERIS
1309
ing. The primarybody consists of a mixed, wherethereare also 5 axial bundles. In Micromesarch protostelein which the large tracheids spermopteris,however, the protoxylemstrands
occur in clusters surrounded by parenchyma. occur on eitherside of the outer edges of the
Secondaryxylemis producedin varyingamounts. metaxylemparenchymaplates,witheach member
Radially elongatebands of fibersare presentin of a pair arisingfroma different
axial bundle. In
the outer cortex, while the inner cortex is de- S. tuedianum,traces are not positionednear the
limitedby horizontalplates of thick-walledcells. parenchymaplates. In Stenomyelonthe presence
betweenthe two of a cylindricalsystemof 5 sympodiais identical
One of the principaldifferences
generais the numberof tracesto the petiole. In to that described in Callistophyton(Rothwell,
Microspermopteris
one trace is present,while the 1975) and Lyginopteris;however, in Stenofrond of Heterangiumis vascularized by 2-10 myelon the basic protostele is maintained.
strands depending upon the level of section Whetheror not the metaxylemwedges and asso(Shadle and Stidd,1975).
ciated protoxylemstrands of Microspermopteris
Vascular rays of Heterangiumbroaden toward shouldbe regardedas sympodiacan notbe stated
the outside of the stem and may appear wedge- withcertaintyat thistime. We have been able to
remain follow the parenchymaplates for up to 3 cm.
shaped, whilethose of Microspermopteris
relativelyuniformthroughouttheir extent. The Serialtransverse
sectionsindicatethattheyremain
mixed,mesarchprotostelesof most Heterangium intact for a considerableextentthroughoutthe
axes usually contain more parenchymathan do stem; however,theydo undergosome change in
steles of Microspermopteris.The large meta- position.
xylemtracheidsof Heterangiumare more circuIn additionto the similarityof the sympodial
lar in transversesection than those of Micro- systemin Microspermopteris
to thatof some other
spermopteris.Throughoutthecourseof thisstudy monostelic seed ferns, the stelar organization
we have noticeda small numberof stemsof Het- may be regarded as occupyingan intermediate
erangiumfrom the Lewis Creek and Derringer position between some calamopityean axes of
Corners localitiesthat have primarybodies that Devonian age and youngereustelicCarboniferous
resemblethe conditionseen in Microspermopterisforms,with referenceto the amount of parenaxes; i.e., the presence of 5 prominentlarge chyma. In a fewstems,especiallythosefromthe
wedgesof metaxylemtracheidsand radiatingarms What Cheer site,we have observeda furtherdisof parenchyma.A fewof theseHeterangiumaxes section of the metaxylemwedges by secondary
rays with just a few filesof parenchyma(Fig. 1). These parenchyma
have uniseriate-biseriate
wedge-shaped vascular rays, but exhibit the plates, however,generallyarise at rightangles
typical petiole anatomy of Heterangium. Until to the principalmetaxylemplates. At some levels
the reproductiveorgans are knownfor both Mi- the numberof these secondaryplates increases
and Heterangium,petiole anat- to the extentthatrelativelysmallclustersof metacrospermopteris
char- xylem tracheidsbecome surroundedby parenomy will continueto be the distinguishing
acter.
chyma. This organizationis quite similarto the
Duringrecentyearstherehas been an increased primary xylem organization of Heterangium.
interestin the primarybody of vascular plants. Thus Microspermopteris
maybe added to a series
This has been broughtabout principallythrough that demonstratesa conversionfromthe protothe work of Beck and co-workers(Namboodiri stele to the eustele by an increasingmedullation
and Beck, 1968 a, b, c) who have describedin oftheprimary
xylemcylinder.
detail the primaryvasculaturein a number of
There are slight differencesbetween Microconiferophytic
gymnosperms.Beck (1970) has spermopterisaxes fromdifferent
localities. For
convincinglydemonstratedthat the eustelicform example, stems fromWhat Cheer typicallydislike that of Lyginopterisor Callistophytonhas play larger primaryxylem cylindersand lesser
evolved by longitudinaldissectionof a protostele amountsof secondaryxylemthan those of equivfollowedby modificationof columnsof vascular alent size fromLewis Creek. The What Cheer
tissue into discretesympodial systemsarranged stemsshow a furtherdissectionof the 5 primary
in a cylinder.Beck has postulateda phylogenetic xylemsegmentsby additionalparenchymaplates
series beginningwith a number of protostelic that extend at rightangles to the 5 main plates
formsincluded withinthe Calamopityaceae be- (Fig. 1, 4). Whetherthisfeatureis a phylogenetic
ginningwithspecies of Stenomyelonand Calamo- trend,since Lewis Creek fossilsare Early Pennpitysand extendingto Lyginopteris.Stenomyelon sylvanian and What Cheer, Middle Pennsylvatuedianum (Kidston and Gwynne-Vaughan, nian, or merelya geographicalvariation,is not
in thatit consistsof a proto- certain.
1912) is interesting
stele divided into 3 longitudinalcolumns by
Of additionalinterestis the presence of epiradiatingbands of parenchyma.Despitethethree- dermaltrichomesand corticalflaps of tissue arisangled appearance of this stemin transversesec- ing fromthe stemsof Microspermopteris.There
tion, traces originatefrom 5 positions. This is are numerous Devonian genera that produced
similarto the organizationin Microspermopteris epidermal appendages varyingfrom what have
1310
AMERICAN JOURNAL OF BIOTANY
[Vol. 63
(Gaspe), and Ontario,Canada. Paleontogr.Amer.
been describedas spines to papillae (e.g., Cre8: 77-127.
naticaulis (Banks & Davis, 1969), Kaulangiostemsand
phyton (Gensel, Kasper and Andrews, 1969), BAXTER,R. W. 1949. Some pteridosperm
fructifications
with particular referenceto the
and
Pertica
(Kasper
1971),
Sawdonia (Hueber,
Medullosae. Ann. Mo. Bot. Gard. 36: 287-352.
Andrews, 1972), Psilophyton(Banks, Leclercq
1952. The coal age flora of Kansas. 1. Miand Hueber, 1975). Epidermalappendageshave
crospermopteris
aphyllumvar. kansensisvar. nov.
been described on the stems of Callistophyton
Trans. Kans. Acad. Sci. 55: 101-103.
(Rothwell, 1975) and Lyginopteris(Oliver and BECK, C. B. 1970. The appearanceof gymnospermous
structure. Biol. Rev. 45: 379-400.
Scott, 1904) in the formof glandulartrichomelike emergences. As far as can be determined FISHER, M. C., AND A. C. Not. 1938. A list of coal
ball plantsfromCalhoun,RichlandCounty. Trans.
fromthe literatureno othersupposed monostelic
Ill. Acad. Sci. 31: 178-181.
seed ferngenera are known with epidermaltri- GENSEL,
P., A. KASPER, AND H. N. ANDREWS. 1969.
interest
is
of
It
of
tissue.
flaps
or
cortical
chomes
Kaulangiophyton,
a new genus of plantsfromthe
to notethatthesurfaceof Stenomyelontuedianum
Devonian of Maine. Bull. TorreyBot. Club 96:
is characterizedby epidermal emergencesthat
265-276.
varyfromshortand bluntto elongateformswith GOOD, C. W. 1975. Pennsylvanian-agecalamitean
cones, elater-bearing spores, and associated vegeswollenends. The authorssuggestthattheymay
tativeorgans. Palaeontographica
B, 153: 28-99.
represent transverse sections of longitudinal
ridges of the stem (Kidston and Gwynne- GRAHAM,R. 1935. Pennsylvanianflora of Illinois as
revealedin coal balls. 2. Bot. Gaz. 97: 156-168.
Vaughan,1912).
HUEBER,
F. M. 1971. Sawdoniaornata: A new name
may now be included with
Microspermopteris
for Psilophytonprincepsvar. ornatum.Taxon 20:
Callistophytonand Lyginopterisas examples of
641-642.
monostelicseed fernsin which axillarybranch- KASPER, A. E., JR., AND H. N. ANDREWS, JR. 1972.
ing is present.Rothwell(1975) has demonstrated
Pertica a new genus of Devonian plants from
the presence of axillarybuds in Callistophyton
northernMaine. Amer. J. Bot. 59: 897-911.
tissue, KIDSTON,R., ANDD. T. GWYNNE-VAUGHAN.1912. On
consistingof a mound of parenchymatous
the Carboniferous flora of Berwickshire. Part I.
in the smallestbuds, with two associated cataStenomyelontuedianumKidston. Trans. R. Soc.
phylls. In some cases the bud, whichis clothed
Edinb. 48: 263-271.
hairs,becomes an axilin a mass of multicellular
MAHAFFY,
1975. Morphologyof MicrosperJ. M.
lary branch with abundant secondary tissue.
mopterisand occurrencesin Middle Pennsylvanian
Oliver and Scott (1904) reportedthe presenceof
coal balls. Bot. Soc. Amer.Abstracts.Allen Press,
(= Lygino"bud-likestructures"in Lyginop-teris
Lawrence,Kansas. p. 22.
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