TAXONOMIC REVIEW OF ASTRANTHIUM INTEGRIFOLIUM (ASTERACEAE: ASTEREAE)

2005·3 MB·English

by  Guy L Nesom

TAXONOMICREVIEWOF
ASTRANTHIUMINTEGRIFOLIUM
(ASTERACEAE:ASTEREAE)
GuyL.Nesom
BotanicalResearchInstituteofTexas
509PecanStreet
FortWorth,Texas76102-4060,U.S.A.
ABSTRACT
Astranthiumintegrijolium(Michx.)Nutt^hasbeentreatedascomprisingtwotaxa(var./subsp.
integrifoliurtiandvar.trijlorum/suhsp.ciliatum)orsimplyasasinglespecieswithoutformalin-
fraspecificdesignation.Thetwotaxaarecompletelyallopatricandseparatedbyfeaturesofvegeta-
tive,floral,andcypselarmorphologyConsistentwithtaxonomicrankingofotherAstranthiiimspe-
ciespairs,thesetwotaxaaretreatedhereatspecificrank:Astranthiumintegrijoliumsensustricto
andAstranthiumciliatum(Raf.)Nesom,comb.nov.AneotypeisselectedforBellisciliatavar.triflora
Raf.(=A.ciliatum).
RESUMEN
Astranthimnintegrijolium(Michx.)Nutt.sehatratadocomprendiendodostaxa(var./subsp.
integri/oHumyvar.tri/Iorum/subsp.ciltatum) simplementecomeunasolaespeciesindesignacion
formalinfraespecifica.Losdostaxasoncompletamentealopatricosyseseparanporlamorfologia
vegetativa,floral,ydelacipsela.Deacuerdoconelrangotaxonomicodeotrosparesdeespeciesde
Astranthium,estosdostaxasetratanacjuiconrangoespeclfico:Astranthiumintegrijoliumsensu
strictoyAstranthiumciliatum(Raf.)Nesom,comb,novSeseleccionaunneotipoparaBellisciliata
var.trijloraRaf.(=A.ciliatum).
ThegenusAstranthiumNutt.includes12species(Dejong1965),allbutthreeof
themrestrictedtoMexico.Astranthiumintegrijolium(Michx.)Nutt.occursin
northeasternMexico,butitsrangeismostlyinthecentralU.S.A.Larsen(1933)
andDeJong(1965)treatedeasternandwesternpopulationsystemsofA.
integrifolium(Fig.1)asvar.integrijoliumandvar.ciliatum(Raf.)Larsen,re-
spectively,orassubsp.integrifoliumandsubsp.triflorum(Raf.)Dejong.
Shinners(1950)addedathirdtaxonatvarietalrank,A.integrifoliumvar.
rohustumShinners,whichsubsequentlywasraisedtospecificrankbyDejong
(1965).SinceDeJong'streatment,TexasbotanistshavemaintainedA.rohustum
(Shinners)DejongasaTexasendemic(Fig.1),butthetaxonomyofthemore
broadlydistributedA.integrifoliumsensulatohasnotbeencriticallyreevalu-
ated.DeJong'sgeographicandmorphologicaldelimitationoftheJntegrifolium
complex'hasbeenacceptedinnationalchecklists(e.g.,Kartesz1999),but
Cronquist(1980)treatedbothgeographicsegmentsasA.integrifoliumwith-
outformalrecognitionofinfraspecifictaxa.Otherfloristicaccountshavedealt
SIDA21(4):2015-2021.2005
2016 BRIT.ORG/SIDA21(4)
Fig.1.GeographicdistributionoiAstranthiumintegrifolium,A.ciliatum,andA.robustum.Squaresandsolidcirclesand
trianglesarefromspecimensatKY,MO,SMU-BRIT,TEX-LL,andVDB.Opensymbolsarefrompublishedsources(DeJong
1965;Chesteretal.1997;GreatPlainsFloraAssociation1977;Smith1988;USDA,NRCS2001).Populationsof».ciliatum
alsooccurinMexico(NuevoLeonandTamaulipas}.
withonlyoneortheotherofthetwotaxa.AccountsforOklahomaandArlcan-
sas(e.g.,Taylor&Taylor1994;Smith1994)alsohavereferrecitoA.integrifolium
withoutfinertaxonomicdistinction,whilethoselorTexasandtheGreatPlains
haverecognizedinfraspecificvariants(e.g.,Correll&Johnston1970;Barkley
1986;Diggsetal.1999).
AreevaluationofAstranthiumintegrifoliumsensulatoindicatesthatthe
twopreviouslyrecognizedgeographicsegmentsareallopatricanddistinguished
byvegetative,floral,andcypselarfeatures.Consistentwithtaxonomicranksof
otherAstranthiumspecies(seecommentsbelow),thetwotaxaaretreatedhere
atspecificrank.
TAXONOMY
1.Astranthiumciliatum(Raf.)Nesom,COmb.novBdUsciliataRa(.,NewFl,N,Amer.
2:24.18.37.AstranthiumtiUc^n[olium(Michx.)Nutt.var.ciliatum(Raf.)I.arsen,Ann.Mis-
souriBot.Card.20;35.1933.Astranthiumintegrifolium(Michx.)Nutc.subsp.ciliatum(Rai.)
DcJong,MiciiiganStateLJniv.Mus.Publ.Biol.Ser.2:304.1%5.Lectotypi-:(DcJong1965):USA.
NESOM.TAXONOMICREVIEWOFASTRANTHIUMINTEGRIfOLIUM 2017
TEXAS.AustinCo.:SanFelipedeAustin,1835,7'.DrummondU.221(NYwebsitephoto!,as
"Be/lisintegrijoliaMichx.";ISOLECTOTYPES:K,NY,P,PH).
BeUisciliataRaf.var.tri/loraRaf.,NewFlN,Amer.2:25.1837.Astranthiumintegrifolium(Michx.)
Nutt.var.trijlorum(Raf.)Shmners,Sida2:348.1966.Neotype(selectedhere):USA.TFXAS.
FanninCo.,4miNofBonham,sandyditchbank,10Jun1945,L.H.Shinners7842(SMU!).
Rafinesquenotedthat"it[presuTnably'Belliscill6i(a'lhasalsoavar.fri/Iora,withleavesallacutish
andonly3[ray]flowers.Theioliolesoftheperianthearelanceolateacuminateinallthesp.
notlinearasHookersays,theseedsareobovatepubescent."BecauseRafinesquenotedthathis
newspecies,Bdliscihata,occurs"inTexasandprobablyextendingtoLouisianaandArkansas,"it
seemsreasonabletoinferthatBellisciliatavar.trijloraalsowasbasedonaTexascollection,
perhapsfromDrummond,whosecollectionsprovidedthebasisforthedescriptionofB.ciliata.
DeJong(1965)alsomadethisinferenceinnotingthatthetypelocalityofvartriflorawas
"Texas."Rafinesque,however,providednoindicationofthetype,andnotypematerialof\'ar
triflorahasbeenfoundorcitedinpreviousliterature.
Smallcapitulawithrelativelyfewandsmallrayfloretsarecommonlyproducedlateinthesea-
soninAstranthiumintegrifohuniandA.ciliatum,but1haveseennoplantswithfewerthan
sixflorets.Plantsoftheneotypeweredescribedasproducing6-8rayflorets.Itseemslikely
thatthecapitulumobservedanddescribedbyRafinesquehadlostseveralrayflorctsduring
collecting,mounting,orhandling.
Astranthiumintegrifolium(Michx.)Nutt.varnisulatumLarsen,Ann.MissouriBot.Card.20:36.
1933.Type:UNITEDSTATES.Texas.MatagordaCo.:Matagorda,sandyprairies,5Mar1914,
E.J.Palmer4855(holotype:MO!).Shinners(1950)accuratelynotedthatthepresenceof
rosulateclustersofleavesreflectsearlygrowthstagesofasingleplant.
2.Astranthiumintegrifolium(Michx.)Nutt.,Trans.Amer.Philos.Soc,ser2,7:312.
1841.BellisintegrifoliaMichx.,Fl.BorAiner.2:131.1803.TYPE:UNITEDSTATES.[Tennessee]
"Cumberland,"A.Michauxs.n.(hoi.otype:RfideDeJong1965).Dejong(pp.434-435)in-
ferredfromhistoricalaccountsthatMichauxprobablymadethecollectioninJune1795in
thevicinityofNashville.Michauxhimself(1803)notedthatthespeciesoccurred"adripas
rivulorumetincollibusumbrosisTennassee.'"Cumberland"istheonlygeographicrefer-
enceontheholotype.
DistinctionsbetweenAstranthiumintegnfoliumandA.ciliatumareinthefol-
lowingcontrasts.
Plantsfibrous-rooted;basalandlowercaulineleaves3-6cmlongX7-22mmwide;
involucres3.5-6mmhigh;raycorollas(6-)8-17mmlong;cypselae(1.4-)1.6-2
(-2.2)mmlongX0.9-1.1mmwide,surfaceminutelypapillate-pebblywithlinear
striationsbarelydiscernible,glabrousorsometimessparselyglochidiate-pubescent
neartheapex,or(innorthernKentuckyandWestVirginia)glochidiate-pubescent
overthewhoesurface Astranthiumintegrifolium
Plantsslender-taprooted,rarelyfibrous-rooted;basalandlowercaulineleaves1.5-4
((-45-))6c-m10(l-o1n2g)xm3m-1lo1n(g-;14c)ypmsemlawei1d-e1;.i6nmvomluclroensg(X2-)02..65--04.,85mmmmwihdigeh,;sruaryfaccoerowliltahs
minutelongitudinalstriaebutotherwisenearlysmooth,notpapillate-pebbly,
sparselytodenselyglochidiate-pubescentfrombasetoapex Astranthiumciliatum
ThemorphologicaldistinctionofAstranthiumintegrifoliumandA.ciliatum
correspondswiththeirgeography,asmappedinFigure1,Thetwoareessentially
completelyseparateindistribution:A.ciliatumoccurswestoftheMississippi
2018 BRIT.ORG/SIDA21(4)
River,A.intcgrijoliumtotheeast.ThedisjunctoutherinHolmesCo.,Missis-
sippi(WoodsonandAndersonJ555,MO!),istypicalA.integri/o/ium;theoutlier
mMississippiCo.,ArkansasiPyle669,TEX!),istypicalA.ciliatum.
Astranthiumintegrifolium was first reported forWest Virginia by
Duppstadt(1992),withoutcitationof vouchers.Detailsaregivenbelow.The
limited,disjunctdistributionandtheoccurrenceprimarilyalongroadsides
suggestthatthisextendedpopulationsystemmightbeofrecentorigin,per-
hapsbyaccidentaldispersalfromKentucky,butthehabitatsappeartobeoth-
erwisenatural.
Collectionsexamined:WESTVIRGINIA.BarbourCo.:alongPleasantCreekPublicHuntingArea
road,extending1.5mi,bothsidesofroaduitoTaylorCo.,26Mayl^)*-)!,Bushs.n.CWVA);PleasantCreek
Huntmg&iMshingArea,roadside,6JunIQ*-)],Chirksons.n.(WVA);alongCo.Road10,betweenHwy
119andTygartLake,NsideolPleasantCax'cl<inPleasantCreekl''ubliciluntingArea;areaolPiuinis.
Liriodcndivn,Acer,Corniis,andCratac\;,us,withmuchinvasiveRosamuUijloniandl.oniccra
maacki]',Aslianlhiumlocallyabundantingrassyhabitatsonroadsides,roadbanks,andadjacent
fields,3Jun2002.Ncsom/WJ54(BRIT,GH,KY,NCU,OS,TENN,TEX,UARK,US,WVA),TaylorCo.:
alongPleasantCreekPublicIiiuitingArearoad,exiending1,5mi,bothsidesolroadintoBarbourCo.,
2JunKX)l./kcr.s.ir(WVA).
DISCUSSION
DeJong(1965,p.510)observedthat"Thetwosubspecies[ol Astranthium
integrifolium]areseparatedfromoneanotherbyquantitativecharactersand
mayberecognizedthroughouttheirrespectiveranges.Theoccasionalfailure
oiasinglecharacteriscompensatedforbyothercharacters.Thekeydiffer-
encesbetweenthetwosubspeciesholdtruewhentheyaregrowninthegreen-
houseunderunilormconditions."Nevertheless,DejongnotedthatinArkan-
sas,subsp.ciliatum"overlaps"and"hybridizes"withsubsp.integrifolium(p.
474andp.505)."Thenumberofspecimenswhicharethoughttobeputative
hybridsisrelativelynumerous,butnotenoughspecimensareavailablefrom
differentlocalitiestoassessthepatternofvariationaccurately"(p.511)."The
recognitionofsubspeciesratherthanvarietiesispromptedbytheconsiderable
rangesofsubsp.integrifoliumandsubsp.ciliatumandtherelativelynarrow
zoneofintergradation"(p.510).
IntergradesbetweenAsiranfliiuniintegrifoliumandA.ciliatumwerecited
byDejong(1965)fromArkansas(e.g.,DemarecI6912-SMU!,Harvey45-MO!,
SMU!,Engelmann129-MO\),Oklahoma(notseen),andMissouri(e.g.,Bush7534-
MO!,Steyermark22642-MO!).Hedidnotspecifythenatureoftheintergrada-
tion,butfromsheetsannotatedbyhim,itcanbeinferredthatthiswasprima-
rilyaninterpretationofrootmorphologyandgeneralvigor(stemheightand
leafsize).The'intergrades'citedfromthesestates(allwithintherangeofA.
ciliatum,asrecognizedhere)tendtobefibrous-rootedratherthantaprooted,
butrareplantsIromTexas(e.g.,GonzalesCo.,Turner37USMU;HarrisonCo.,
Orrl82-SMU)alsoareweaklyiibrous-rooted;allol theseareinterpretedhere
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aspopulationvariantsratherthanintergrades,becausetheybelongwithA.
ciliatumininvolucralheight,raycorollalength,andespeciallyincypselarsize,
surfacemorphology,andvestiture.ThesameistruefortwoArkansascollec-
tionscitedbyDejongasA.integrifoliumsubsp.integrifolium(HotSpringsCo.,
Soulards.n.-MO!;WashingtonCo.,Harveys.n.-MO!)andforMissouricollections
annotatedas"aff.subsp.integrifolium"(e.g.,Palmer39297-MO],Palmer39483-
MO!,SteyermarkJ0393-MO!).SomeArkansascollectionscitedbyDejongasin-
termediatebetweenthesubspecieswereannotatedbyhimsimplyas"A.
integrifoliumsubsp.ciliatum"(e.g.,Bush929-MO[,Pa/mer5992-MO!).
Robustplantsof Astranthiumciliatumare similar in habit to A.
integrifolium,anddepauperateplantsofA.integrifoliumaresimilarinhabit
toA.ciliatum.TheArkansascollectionsinterpretedbyDejongas"subsp.
integrifolium"orasreflectinghybridizationweremadearoundHotSprings
(HotSpringsCo.)andFayetteville(WashingtonCo.).Theseplantsaregener-
allytallerthanaverageforthespecies(upto32cmtall)andhaveleavesthat
rangelarger,andsomehavefibrousroots,butininvolucralsize,raylength,and
cypselarmorphology,theybelongwithA.ciliatum.Cypselaeofplantsfrom
ArkansasandMissourialsorangelonger(Ll-1.6mm)thaninTexasandOkla-
homa(1-L2mm).Whetherthelargersizesoftheseplantsmightreflectcon-
vergenceoranancestralsimilaritywithA.integrifoliumsensustrictoisnot
clear.Eventhoughvariousfeaturesoverlapinvariation,featuresofcypselar
morphology(vestitureandepidermalsurface)provideconsistentdistinction
betweenthetwotaxa,especiallywithrecognitionofthedisjunctionintheir
geographicranges,and1havenotseenanyplantthatcouldberegardedasin-
termediate.
Insummary,thepresentstudyfindsthatthereisnounequivocalevidence
forhybridizationbetweenplantsofAstranthiumintegrifoliumandA.ciliatum.
Infact,theirallopatricdistributionallowsnoopportunitytorgeneticinterchange,
anddifferencesincypselarmorphologysuggestthatisolationiscomplete.
CONSISTENCYINTAXONOMICRANK
MorphologicaldistmctionsbetweenAstranthiumintegri/oliumandA.ci/iatum
arerelativelysmall,buttheirpatternofrelationshipandtreatmentatspecific
rankareanalogousandconsistentwiththetaxonomyofspeciespairs(asrec-
ognizedbyDejong1965)ofAstranthiumfoundinMexico.Thetwoareessen-
tiallyidenticalinchromosomenumber(2n=8)andchromosomemorphology
(Dejong1965).Theirnortherndistributionsandmorphologicalsimilaritysug-
gestthattheyhaveanevolutionarysisterrelationship.Dejong(p.523)noted
thatA.rohustum(2n=6)"isrelatedtoA.integrifolium"...but"thespeciesalso
showsresemblancetoA.condimentumandA.orthopodumandhasthesame
chromosomenumberandkaryotypeasthesetwospecies."
TherelationshipofAstranthiumorthopodum(B.L.Rob.)E.LarsenandA.
2020 BRIT.ORG/SIDA21(4)
condimentumDeJongparallelsthatofA.integrifoliumandA.ciliatum.They
aresimilartoeachotherinchromosomenumber(In=6)andchromosome
morphologyandprobablyareevolutionarysistertaxa.Eachhasasubstantial
geographicrange,buttheyareallopatricindistribution.Theyaremorphologi-
callyseparated primarilyon the basisof root characters:plantsof A.
condimentumareannualsfromaslendertaproot;plantsofA.orthopodumare
biennialsorshort-livedperennialsfromafibrous-rootedcaudex,sometimes
withshortrhizomesorbasaloffsets.Additionally,therearesmallandoverlap-
pingdifferencesinstemorientationandleafshapeandsize.
AstranthiumsplendcnsDejong{In=18)andA.heamaniiDeJong(2n=
24)bothapparentlyhaveabasechromosomenumberofx=3andalsoprob-
ablyareevolutionarysistertaxa.Theyaresympatricbutgrovv'atdifferentel-
evationsandareotherwisedistinguishedonthebasisofcypselarvestiture(and
apparentlynothingelse):cypselaeofA.splendensareglochidiate-hairyover
the wholesurface while those of A. bcamanii areglabrousorsparsely
glochidiate-hairyonlyneartheapex.
ACKNOWLEDGMENTS
LoansofspecimensfromKY,MO,WKU,andWVA,helpofTEX-LLstaffdur-
ingarecentvisit,helpfromDonnaFord-Werntz(WVA)andBillGraftoninthe
investigationoftheWestVirginiaplants,andreviewcommentsofGeorge
Yatskievycharegratefullyacknowledged.
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