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THE NATURAL HISTORY MUSEUM VOLUME 26 NUMBER 2 28 NOVEMBER 1996 TheBulletin ofTheNaturalHistoryMuseum (formerly: Bulletin ofthe British Museum (NaturalHistory)), instituted in 1949, is issued in four scientific series, Botany, Entomology, Geology (incorporating Mineralogy) and Zoology. The Botany Series is edited in the Museum's Department ofBotany KeeperofBotany: Dr S. Blackmore EditorofBulletin: Ms M.J. Short Papers in the Bulletin are primarily the results ofresearch carried out on the unique and ever- growing collections ofthe Museum, both by the scientific staffand by specialists from elsewhere who make use ofthe Museum's resources. Many ofthe papers are works ofreference that will remain indispensable foryears to come. All papers submitted forpublication are subjected to external peer review for acceptance. A volume contains about 160 pages, made up by two numbers, published in the Spring andAutumn. Subscriptions may be placed forone or more ofthe series on an annual basis. Individual numbers and back numbers can be purchased and a Bulletin catalogue, by series, is available. Orders and enquiries should be sent to: Intercept Ltd. P.O. Box 716 Andover Hampshire SP10 1YG Telephone: (01264) 334748 Fax:(01264)334058 Claims for non-receiptofissues ofthe Bulletin will be met free ofcharge ifreceived by the Publisher within 6 months forthe UK, and 9 months forthe restofthe world. World List abbreviation: Bull. nat. Hist. Mus. Lond. (Bot.) The Natural History Museum, 1996 Botany Series ISSN 0968-0446 Vol. 26, No. 2, pp. 75-217 The Natural History Museum Cromwell Road London SW7 5BD Issued 28 November 1996 TypesetbyAnnBuchan(Typesetters),Middlesex PrintedinGreatBritainbyHenryLingLtd.,attheDorsetPress,Dorchester,Dorset Bull. not. Hist.Mus. Land. (Bot.)26(2): 75-217 Issued28November 1996 Studies in the genus Hypericum L. (Guttiferae) 6. Sections 20. Myriandra to 28. Elodes THE NATURAL HISTORY MUSEL NORMAN ROBSON K.B. DepartmentofBotany, TheNaturalHistoryMuseum, CromwellRoad, London SW75BD .PRESENTED CONTENTS Introduction 76 SeparationofsectsAdenosepalumandHumifusoideumfromtherestofKeller'ssect.Euhypericum 76 Circumscriptionofseel.Adenosepalum 76 Sect. 20.Myriandra 76 Subdivision 76 Charactersandvariation 78 Leaves 78 Inflorescence 78 Flowersandfruits 79 Cytologyandhybrids 79 Distributionandevolution 79 Sects21. Webbiaand22.Arthrophyllum 82 Charactersandvariation 82 Distributionandevolution 83 Sects23. Triadenioides,24.Heterophyllaand25.Adenotrias 83 Charactersandvariation 83 Distributionandevolution 84 Sect.26.Humifusoideum 85 Charactersandvariation 85 Distributionandevolution 87 Sects27.Adenosepalumand28.Elodes 88 Evaluationofsect.Elodes 88 Charactersandvariation 89 Morphologyandsubdivision 89 Cytologyandhybrids 90 Distributionandevolution 90 Systematictreatment 92 Sect.20.Myriandra(Spach)R.Keller 92 Sect.21. Webbia(Spach)R.Keller 133 Sect.22.ArthrophyllumJaub.&Spach 137 & Sect.23. TriadenioidesJaub. Spach 141 Sect.24.HeterophyllaN.Robson 146 Sect.25.Adenotrias(Jaub.&Spach)R.Keller 147 Sect.26.HumifusoideumR. Keller 153 Sect.27'.AdenosepalumSpach 170 Sect.28.Elodes(Adans.)W.Koch 208 References 212 Systematicindex 214 SYNOPSIS. Followingcitationofthetypeofanewsubspecies(H.silenoidessubsp.minusN.Robson)omittedfromPart8,those sectionsofHypericumdirectlyrelatedtosect. 1.CampylosporusthatwerenottreatedinPart3areconsidered,aswellassects 22.Arthrophyllumand28.Elodes,whicharecloselyrelatedrespectivelytosects21.Webbiaand21.Adenosepalum.Adiscussion ofthemorphology,chromosomenumbers,hybrids,distributionandevolutionofeachsectionisfollowedbyasystematicaccount ofthe81 speciesintotalthattheycontain. Sect.20.Myriandraisdividedintofivesubsections:subsect.CentrospermaR.Keller,subsect.PseudobrathydiumR.Keller, subsect. Suturosperma R. Keller, subsect. Brathydium (Spach) R. Kellerand subsect. Ascyrum (L.)N. Robson stat. nov., all additionaltoorwithcircumscriptionsdifferentfromthoseinAdams's1962paper;and//,tenuifoliumPurshreplaces//,reductum W.P.Adams. Sect. 27.Adenosepalum isdivided intofoursubsections: subsect.AethiopicaN. Robson, subsect. PubescentesN. Robsen, subsect. Caprifolia N. Robson and subsect. Adenosepalum; and H.joerstadii Lid is treated as a hybrid, H. glandulosum x reflexum. TheNaturalHistoryMuseum, 1996 N.K.B. ROBSON 76 Bupleuroidestheleafpairs areconnate andglabrous andthe styles INTRODUCTION basallyappressed;andinsects9.Hypericumand 14.Oligostemathe petals become (roughly) erect after flowering, not tightly twisted Thispart(Part6)oftheHypericummonographincludestreatments round the developing ovary as in sects 27. Adenosepalum and 28. oftheremainingsectionsdirectlyrelatedtothemainlyAfricanSect. Elodes. Sect. Adenosepalum is therefore distinguishable among 1. Campvlosporus (sects 20-28), sects 2-3 having been treated in species of 'sect. Homotaenium Boiss.' by the combination offree Part 3 (Robson, 1985) and sects 29-30 in Parts 7 and 8 (Robson, leaf pairs with inframarginal black glands (or if leaf pairs are 1987, 1990). Parts4 and 5 will include the remaining sections, all connate they are pubescent), petals twisting round the developing directly relatedtotheAsian sect. 3.Ascyreia (sects7-19). fruit, 3 distinct stamen fascicles (cf. sect. 26. Humifusoideum) and Before turning to the main concern of this part, however, it is seedswithalinear-reticulatetoscalariformtesta.Thepresenceofan necessarytoremedyanomenclaturalomissioninPart8.Thetypeof indumentum in many speciesdistinguishesthese from membersof Hvpericum silenoides subsp. minus, endemic to the Galapagos sects9and 14,whilstthewidespreadoccurrenceofflat-toppedsepal Islands (Robson, 1990: 90), shouldhavebeencitedas: & marginal glands in sect. Adenosepalum is paralleled only in some Ecuador,GalapagosIslands,AlbermarleIsland [Isabella], 825 speciesofsect. 17. Hirtella. Sect. 28. Elodes isdifferentiatedfrom 945m,28August 1905(fl),Stewart2064(BM!-holotype;GH!,K!, sect.Adenosepalumprincipallybythefloral modificationstowards MO!-isotypes). specialized insect pollination, but also by the red marginal sepal glands, the ribbed-scalariform seed testa and almost always by the Separation ofsectsAdenosepalum and absenceofinframarginal black leafglands. Humifusoideum from the rest ofKeller's sect. Circumscription ofsect.Adenosepalum Euhypericum Whentheforegoingcriteriawereconsidered, itbecamecleartome Sects20-28fallintosixquitedistinctgroups,eachrelateddirectlyto that the Himalayan, south Indian and Chinese species that I origi- ssetcatm.e1n.sCaampppvalreonstployrunso:t(fi)as2c0i.cMuylartieanadnrda,blwaictkh2gl-a5nsdtsylaebssenatp;pr(eiis)se2d1,. nbaellloyngintchleurdee.dTihnesepcutt.atiAvdeen'olsinekpiangl'umspe(cRioebss,ont,he \H9i1m1abl)aydaon nHo.t Webbiaanditsderivative22.Arthrophyllum,with3stylesspreading elodeoidesChoisy,isinfactcloselyrelatedtoH.hengshanenseW.T. from non-contiguous bases, stamens '3'-fasciculate, black glands Wang, from SE China (Jiangsi, Hunan, Guangxi, Guangdong). absentorpresentandleaves broadwithdenselyreticulatevenation; Indeed,Li(1990:6)broughtthesetwospeciestogetherinhiskeyto (iii) 23. Triadenioides, with 3 styles spreading from contiguous Chinese Hypericum, placingboth in sect. Adenosepalum. bases,stamens'3'-fasciculate,blackglandspresentonlyinthemost Three glabrous, western Asiatic species allocated to sect. derived species and leaves broad (but without clearly reticulate AdenosepaluminPart 1 andpreviouslyinFloraofTurkey(Robson, venation)to microphyllous;(iv)24.Heterophyllaand25Adenotrias, 1961b)mustalsobeexcludedandtransferredtosect. 12.Origanifolia. with3stylesspreadingfromcontiguousbases,stamens'3'-fasciculate, TheseareH. huber-morathiiN.Robson,H.minutumPoulterandH. blackglandsabsentandleavesmicrophyllous;(\)26.Humifusoideum, formosissimum Takht. They were originally excluded from sect. winidtehfin3i-t5e ssttaylmeesnsfapsrceiacdliesn,gbflarcokmglcaonndtsiguusouuasllybapsreess,en't3'a-n5dlreaatvheesr cOhrairgaacntiefroilstiiacboefcaHu.seortihgeainrifcoalpisuumleWsillladc.keadndthHe.sawvoilcluelnariviefsoilciluesm broad;and(vi)21.Adenosepalumanditsderivative28.Elodes,with Jaub. & Spach. H. minutum and H.formosissimum, however, have 3blasctykle(sorsprreedadiinngsecftr.om28c)ongtliagnudosusprebasseenst,a'n3d'-lfeasacviecslebdrosatda.meTnhse, ianntderHr.upstaeldsuvigtitnaee,umwhNi.cRhobarseonal&soHfuobu.n-dMoirn.,H.boitmhbcrliecaarltyumrelPaotueldtetro distributions of these groups are: Group (i) Eastern N. America, H. aviculariifolium;andH. minutumisclearlycloselyrelatedtoH. eastern Mexico, Belize, Guatemala, Honduras Republic, Greater huber-morathii. When other characters, such as glandularity, leaf Antilles, Bahamas, Bermuda; (ii) Macaronesia, eastern Mediterra- and flower colour and habitat (all in limestone rock crevices), are nean;(iii)Socotra,SWTurkey,Levant;(iv)NWAfrica,Mediterranean, taken into consideration, there can be little doubtthattheircorrect NW Turkey; (v) New Guinea, Luzon, Taiwan, Sumatra, Java, S. position is nearH. aviculariifolium. AMfarciacraonetsoiaE,thAiforpiicaa,aWn.dAErqaubaitao,riEaulropGeu,inWe.a,CaMuacdaasguass,caWr.;&(viS). sectW.itAhdtehneotsreoppiaclaulmancdaenasbteAsisaeteincatondhAanvaetoiltisanprsipmeictiivees,exschlruudbebdy, Tiunrckleuyd,edLeivnasnetc.t.NAodteentohsateptarolpuimcalbealnodngeaisntfAascitattiocssecpte.ciHeyspheirtihecrutmo swpheoclileys gilnabMraocuasr;on(iei)siNaWandAftrhirceaeadnedrivtahteivCeagnraoruypsI:sl(ai)ndAsfrtioca(na,) sensulato(seebelow). SomalilandandwesternArabiaand(b)thewesternMediterranean, Althougheachofthesegroups iseasily distinguishablefromthe wholly with indumentum; (iii) Europe to western Caucasus and others,membersofsects26(Groupv)and27(Groupvi)haveoften adjacentTurkey,theMediterraneanandEthiopia(withadjacentNE been includedin abroadsect. Euhypericum Boiss.,forexampleby Sudan and Arabia) to northern Tanzania, nearly always with Keller (1925: 177). Keller placed such species in his subsect. indumentum. H. elodesL. (sect. 28. Elodes) isderivedfrom group Hcoonmtoatianeendimuoms,tboyftfhaerstpheecilearsgewsitthsunbasrercotwiocnonintitnhueoussecltoinogn,ituwdhiincahl (iinit)oagnrdoHu.pa(fi)rruamthLearmt.ha(nfrionmsTecutn.is9i.aHaynpderaidcjaucme,ntwhAlegreeriIa)orfiigtisnwaelllly voiutstaaegognlotmheercaatpisounleovfalsvpeesc.ieAsttweemrpetsmtaodreatiboynaSltizeefatnhoifsfhe(t1e9r3o2g-e3n4e)- located it (Robson, 1977a). and Kimura (1951), both ofwhom divided it into sections, and by Gorschkova (1949), who retained Keller's subsect. Homotaenium Sect. 20. Myriandra butdivideditinto 15series.InPart 1 ofthiswork(Robson, 1977a), IdistributedKeller'sspeciesamongsections8,9, 14, 17, 18,26and Subdivision 27. Sects 17. Hirtella and 18. Taeniocarpium are distinguished amongthesebyhavingnoregularintramarginalrowofblackglands This well-delimited section comprises 29 species and4 subspecies onthe leaves and seeds with asmoothtopapillosetesta; in sect. 8. thataremostly shrubsorwiryshrubletsbutincludeafewperennial STUDIES INHYPERICUM 77 Sect. 20Myhandra Relationships 7. tenuifolium 18 11. brachyphyll1u8m 19. microsepalum 21 adpressum 22.ellipticum 18 18 9c. nitidum ssp. exile 13.fasciculatum 20. sphaerocarpum 9b. nitidum ssp. nitidum SUTUROSPERMA 29c. hypericoides ssp. prostratum 16.apocynifolium 17. nudiflorum 29b. hypericoides 8. lloydii ssp. multicaule 9a. nitidum ssp. cubens PSEUDO- BRATHYDIUM 5. densiflorum . tetrapetalum 15. buckleyi 18 4. lobocarpum 18 27. edisonianum 24.dolabriforme / 18 CENTROSPERMA BRATHYDIUM 28.suffruticosum 3. kalmianum 18 18 23. myrtifolium 18 1. frondosum 25.crux-andreae 29a. hypericoides 18,36 18 ssp. hypericoides 18 Fig. 1 Sect.20.Myriandra.Relationshipsandchromosomenumbers(2n)ofthe29species.Limitsofthe5(named)subsectionsindicatedbyboldlines. herbs.They all lackblackglands and have stamenfasciclesclosely Subsect.Centrosperma-shrubs;leavesandsepalswitharticulationor merged, so thatthe androecium appears to be polyandrous and (in grooveatbase;sepals5(4),deciduous;petals5(4);stamensdecidu- contrasttosect.30.Trigynobrathys}remainssoeveninthesmallest ous. 15 species, i.e. Spp. 1-14 in the present treatment + 23. H. flowers.Thestylesareslenderandcloselymutuallyappressedinthe myrtifolium. moreprimitive species; butthey have atendency to part in fruitin Subsect. Pseudobrathydium -shrubs and perennial herbs; leaves and moreadvanced4-petalledones('Ascyrum").Thestigmasaresmall. sepals withoutarticulationorgrooveatbase; sepals5-4, persistent MyrKielalnedrra(1i8n9t3o,th1r9ee25m)aidnivsiudbegdrotuhpes,grvoizu.pAtsrceyarteudmhaenrdetawsosseecct-. 2(ind4e-Hc.2i9nduuiodnuitsfhleionrpHru.emsneaunndtditfHrl.eoaartpumomec)ny;tn.pieftoallisu5m^)4.;1s4tsapmeecnisesp,eir.sei.sStpenpt.(1e5x-c2e2p,t tionsofHypericum,witheachsectionofHypericumcontainingtwo subsections: Fromtheseattemptsatinfrasectionaldivisionitwouldappearthat AHsycpyerriucmu-ms-epsaelpsalasndanpdetpaeltsal4s;5p;lapcleancteanttiaotniopnaraixeitlael;tostpyalreiset2a-l3.(4). tshpeerceieasre(Ht.hrebeuckmlaejyoi,r gHr.ounpusdi(falsorKueml,lerH.praoppoocsyendi)f,olbuitumthaantdfoHu.r Sect.Mvriandra-stamensdeciduous;placentationaxiletoparietal;styles myrtifolium)fallawkwardlyacrosstheproposedgroupdivisions.In 3-5. addition,theAscyrumgroupisheterogeneous,asSpach(18366)had Subsect. Centrosperma-placentationaxile,pyramidal. already realized. Most species have two unequal pairs of broad Subsect.Suturosperma-placentationparietal. appressedsepals,butin 19.H.microsepalumtheyareequal,narrow Sect. Brathydium - stamens persistent; placentation parietal or rarely and recurved. Spach placed the latter in a monotypic genus, axile;styles3. Isophyllum,as/,drummondii;anditisclearlynotrelatedtotheother SSuubbsseecctt..EPsueburdaotbhryadtihuymd-iupmla-cepnltaacteinotnatpiaorinetaaxli.le,pyramidal. 4h-apveetableleendsdpeercivieeds.butto 18.H. cistifolium,fromwhichitappearsto FollowingtheinclusionoftheAmericanspeciesofAscyruminsect. Thesuggestedinterrelationshipsofspeciesinsect.Myriandraare Myriandra (Adams & Robson, 1961), Adams (1962) recognized showninFig. 1,alongwiththefivesubsectionsintowhichtheyhave only one section, subdividing it intotwo subsections: beendividedhere. Itwillbeseenthattherearetwobasalspecies(1. 78 N.K.B. ROBSON H. frondosum and 2. H. prolificum, both variable, especially the Suturosperma (Spp. 16, 17), Brathydium (23. H. myrtifolium) and latter), from which the remaining species have been derived. H. Ascyrum (Spp. 25, 26) but is wholly absent from subsect. frondosumisdirectlyrelatedtotheAscyrumgroup(Spp.25-29)and Pseudobrathydium(15. //. buckleyi).Thischaracterchangeisasso- the Brathydiutn group (Spp. 23-24), whereas the Suturosperma ciated with a tendency for the point ofleaf-fall to move from the group(Spp. 16-22)and//,buckleyi(Sp. 15)aredirectlyrelatedto//. basalgroovetothepetioleorpseudopetiole. Delayedbasal leaf-fall prolificum(asare Spp. 3-14). is found in 16. H. apocynifolium, 17. H. nudiflorum, 25. H. crux- From Fig. 2, which showsthe limitsofcertaincharacters, itwill andreaeand26.H.tetrapetalum,whilesuprabasalleaf-falloccursin be clear why Keller and Adams had difficulty in defining their 15. H. buckleyi, 18. H. cistifolium, 19. //. microsepalum and the subdivisions and why nohard andfast linescan bedrawn between remainderofsubsect.Ascyrum (Spp. 27-29). Myriandrasensustricto(Spp. 1-14)andtheremainingspecies.The In the linear- to acicular-leaved species, there is a contrast be- groups outlined above, however, can be treated as five reasonably tweenthoseinwhichthemarginisrevolutebuttherestofthelamina well defined subsections: unaltered(12. H. lissophloeusand the H. galioides and //. nitidum groups, Spp. 6-11)andtheH.fasciculatumgroup(Spp. 13, 14), in 1. Subsect. Centrosperma (p. 94)-Sepalsandpetals5; sepalsand which the midrib area is raised beneath, forming agroove on each stamens deciduous; leaves and sepals articulated; sepals very sidebetween itand the revolute margin (cf. Fig. 2). unequaltosubequal;styles(2)3-5(6);placentationincompletely INFLORESCENCE. The inflorescence of the near-ancestral //. axile toparietal; shrubs. Spp. 1-14. synstylum is 1-2-flowered, a state that is reflected in the 1-3- 2. Subsect.Pseudobrathydium(p. 112)-Sepalsandpetals5;sepals flowered basic inflorescence of sect. Myriandra (usual in 1. //. and stamenspersistent; leaves and sepals notarticulated; sepals frondosum). Two evolutionary tendencies lead to (i) the involve- subequal; styles 3; placentation incompletely axile; low shrub. ment of an increasing number of nodes in flower-bearing Sp. 15. (basipetal)and(ii)anincreasingdegreeofcymose(i.e.dichasial/ 3. Subsect. Suturosperma (p. 113) - Sepals and petals 5(4-3); mnaonntochinassiuabls)ecbtr.ancCheinntgro(ascpreorpemtaa,l).leBaadsiinpgetatlobtrhaenchlionnggisnadormrio-w sepalsandstamensdeciduousorpersistent;leavesandsepalsnot inflorescences of H. galioides, H. nitidum, H. lissophloeus and articulated, sepals unequal or usually subequal; styles 3(4); their relatives. Acropetal branching is dominant in subsects placentation incompletely axile to parietal; shrubs or perennial Suturosperma, Brathydium and Ascyrum, where involvement of herbs. Spp. 16-22. more than three nodes is rare, occurring only in forms of25. H. 4. Subsect. Brathydium (p. 122) - Sepals and petals 5; sepals crux-andreae and 29. H. hypericoides. Pseudo-dichotomous persistent, stamens deciduous or persistent; leaves articulated branchingisconfinedtosubsect.Ascyrum,whereitoccurswholly incompletely or not at all, sepals not articulated; sepals very or partly in all species. utboneepqadriuisaetltiantlog;ussiuhsbrheueqbdusafolrr;ossmutbytlshehesru3pb(rs4e).c;Seppdlpia.ncge2n3ot-na2tei4ob(nyTihnitchseosmuupbnlseeetqceutlaiylonaxacinalnde eFvLoOlWutEiRoSnaAryNDreFdRUuIcTtSi.on Rinefenruemnbceesrhoafveflboeraeln mmaedmebearbsoveintosetchte. persistent sepals, more numerous stamens and widely branched Myriandra.Thepolyphyleticreductionfrompentamerytotetramery 5. Siunbfsleocrte.sceAnscce,yrsueemk(epy. p1.2943)).- Sepals and petals 4: sepals and atinridtmhieemreporeuorsiuasenxtcgheyipnstoaesicsnioucSmip.apt.eTd2hi-en5,sguwbyshneeocrete.ciAtushmceryerisuamoptpwheieatrrhwiatsoreehdaruvecgetuilobanereltnyo stamens persistent; leaves articulated or not, sepals not articu- secondaryincreasesto4-5-mery,andoccasionally inthegalioides, lated; sepals very unequal; styles 2-3(4); placentation parietal; nitidum andfasciculatum groups (Spp. 6-14). shrubsorwiry shrublets. Spp. 25-29. The sepals areprimitively unequal (e.g. in 1. //.frondosum) and remainmarkedly so intetramerousformsofthatspecies and inthe Characters and variation (Fig. 2) directly related subsect.Ascyrum, where the outerpairis largeand T(Hbc1o.lhna.ethcHryk.sappfcegertlrcioaiionnecndsodsiooi,dsnfeuasstmnehc)dsetu.tbtaoMshnypemd.rirpinpoeaurletnolcedsuitcrupriarmdaotvsgtuatolmrra)yaan.tpfdepArsmaosraametrmnbe-etufnasotplhriowymolainyysneahsgndrdupwarbuibsnyrocyutvipsiehfetaotrocrhbc3emsoy.m(ml2Tpt9ahaaccle-.kl artsaelempslatptylrrolaebfmsoeestrrcehoedeouvmss(eeecncsoptenaircbloiesenasaenslen,tixthnc,(sgeiopn1tt9hst.eshouaHdmtb.eseveimcefntilo.cortrpmBhioesrnsaogetofpthfahy2relu8diru.itmu)H,sm.ap,entscthduiehfeetfsshrieeunptweiaiiqnlctunsoaheslrauiramtpe)ya.uiagsrIlrunmavaodeltusrlh-tyye nied by trends towards a reduction in number of members ofthe equal. In subsect. Brathydium (Spp. 23, 24), however, both species floral whorls. have unequal sepals, although the inequality is less in 24. H. dolabriforme than in 23. H. myrtifolium. The curved-dolabriform LEAVES. The most closely related species to sect. Myriandra in (hammer-shaped)petalsintheformerarethemostextremeinform sect. 1. Campylosporus is the north-east African H. synstylum, in the section. Otherwise the petals do not provide specifically whichhaspinnateleafvenation.Thusthevenationinsect.Myriandra distinctcharacters.The trendfromdeciduoustopersistentstamens isalsobasicallypinnate.Intheprimitive,broad-leavedspecies(e.g. hasalreadybeen mentionedabove, andthestamensotherwisevary 1.H.frondosum)thetertiaryreticulationisverydenseandclear,but only in numberand length, decreasingfromc. 650ofupto 12 mm mm itislessclearorobscure in species with thickerleaves (e.g. 18. //. long(1.//.frondosum)toc.30of2.5-4 (28.H. suffruticosum). cistifolium). The more advanced species in subsect. Centrosperma The relatively large number of stamens is one of the reasons for have linear, often needle-like leaves with only a midrib visible associating//,dolabriformewithH.myrtifoliumratherthanwith20. beneath. H. sphaerocarpum. Theoccurrenceofagroovewheretheleafjoinsthestem('leaves Theovaryplacentationisnevertrulyaxile,i.e.theplacentaenever articulated') is a plesiomorphic character in Hypericum in general meet in the middle ofthe ovary. The primitive state, incompletely andinsect.Myriandrainparticular(Fig.2).Itisconstantinsubsect. axileorpseudo-axile,isfoundinSpp. 1-5ofsubsect.Centrosperma Centrosperma and present in primitive members of subsects andinsubsect. Pseudobrathydium(Sp. 15)and23. H. myrtifolium. 79 Sect. 20Myriandra Characters Inflorescencebranchingmainlybasipetal \ Inflorescencebranchingmainlyacropetal Stamensdeciduous Fig.2 Sect.20.Myriandra.Limitsofcertaincharacters.Notetheisolatedapomorphicoccurrencesof5(6)-styledandpersistentstamensrespectively. Elsewhere there are parallel developments to truly parietal species of sect. Campylosporus in which (i) the styles are com- placentation in all subsections. The variation in testapattern ofthe pletelyunitedeveninfruitand(ii)therearetendenciesforthepetals seedsisnotsogreatasitisinsomeothersections:fromreticulateto to fall tardily (H. quartinianuni) and for the black glands to be finely scalariform via scalariform-reticulate and linear-foveolate. completelyabsent(H.synstylum).Inthesespecies,too,thedevelop- ment ofpinnate venation is almost complete, only the lowermost Cytology andhybrids (Fig. 1) pairoflateralveinsoroneofthemremainingfree.H. quartinianum occursfromsouth-westernArabia(Yemen)tonorthernMalawiand Tnh=e9c,h2rnom=o1s8o,meexcneupmtbfeorrainreseccotr.dMoyfri2ann=dr1a6ifsoarl2m2o.stH.coenlsliisptteinctulmy, nisorctohnefrinneMdoztoamtbwioqaudej,acwehnitlsatretahseirneleaatsitveerlynaEptohmioopripahi(cH/a/r.ars)yansntdyolnuem Ha=.t1ed1ter-na1sp4ilof(ilAdodrrauemmcsof,rrdo1f9mo5rM9)a1..cHDo.ensfprCioot.ne,dtoNhsoisrutmrhe(lpCa.tair9vo6el)uiannniadftoharamptiohtpayudloaf2tnciho=nro2o7mf,o5-n. AinfrTnihocreatrheaenridsnasSoowumitahdl-eieaad.sitsterrinbuUt.iSo.nAa.l,gawph,erteher1e.fHor.ef,robnedtwoeseunm,notrhteh-meoasstt some number, natural hybrids appear to be very rare except in primitive species in sect. Myriandra, occurs sporadically from cultivation, which suggeststhatthe speciesare isolatedbyecologi- Kentucky to Georgia and eastern Texas. There is a considerable cal and/orbiologicalfactorsratherthanby geographical separation morphological gap, too, as H.frondosum has deciduous petals and alone.Thecultivatedhybrids,whicharosespontaneouslyanddoubt- stamens,thestamenfasciclesarecompletelyunitedwithaconsider- lesscontinuetoappearwhensuitablespeciesaregrowntogether,all ablyincreasednumberofstamens,andtheovaryis3-merous.Inthe involve Spp. 1-6only. leaves, the acute to obtuse apex ofthe African plants has become Distribution andevolution (Fig. 3) apipnincautlea,tew-oibtthusweidtoelryousnpdreeda,dianngd(tnhoetveansacteinodninigs)whloaltelryalcs,lodseendsaenldy The north-eastAmerican andCaribbean sect. Myriandra is, aswas reticulatetertiary venation and punctate(notelongate) glands. noted in Part 3 (Robson, 1985: 169), mostclosely related to those FromH.frondosumthreecladesdiverge(i,vii,viii),thesecorre- 80 N.K.B. ROBSON Sect. 20. Myriandra Distribution 14 nw Fla NC-c Fla s Ala II Ga->La 13 se NC-*.Fla Miss 9c |9 s Ga, nw Fla NC--n Fla- e Tex w Cuba 9b nw Fla s SC, Ga, n Fla, e Ala 21 22 NC -*e La 18 Mass -*-Ga- Minn-Nfld Tenn, Mo, WVa, Tenn 111, Ind 9a NJ-+Ga, Ala-Pa w Cuba, Belize 16 Va, Tenn-nw Fla 20 Ga Fla lowa^Ohio^ La' Ark Miss, [La], e Tex? n A^-a-*ne Tex, e Okla 17 e Tex, e Okla -( Ga?, SC c Fla Mass-vSC-y 26 n Tex-*s Ohio Que, Ont, Wis-*NY 23 sFlGaa,, ws CAulbaa, 29 b SC?, Ga-Miss s NC-e La, c Fla 28 c Hisp (Dom R) 29a 29c se NY-Fla-e Tex, e Okla Va-*Fla--e Tex, Okla-Ky; e Mex-rHond; Gr Ant, Jam; Bah, Berm; [Azores] Fig.3 Sect.20.Myriandra.Distributionofthe29species,showingmajor(==)andminor( )disjunctionsandtrends(-).Lowercaselettersindicate compasspoints;squarebracketsindicateextinctions(Sp. 17)orintroduction(Sp.29c);romanfiguresindicatemajorclades(seetext).Geographical abbreviationsusedinFig.3:Ala-Alabama,Ark-Arkansas,Bah-Bahamas, Berm-Bermuda,DomR-DominicanRepublic,Fla-Florida,Ga- Georgia,GrAnt-GreaterAntilles,Hond-HondurasRepublic,111-Illinois,Ind-Indiana,Jam-Jamaica,Ky-Kentucky,La-Louisiana,Mass- Massachusetts,Mex-Mexico,Minn-Minnesota,Miss-Mississippi,Mo-Missouri,NC-NorthCarolina,Nfld-Newfoundland,NJ-NewJersey, NY-NewYork,Okla-Oklahoma,Ont-Ontario,Pa-Philadelphia,Que-Quebec,SC-SouthCarolina,Tenn-Tennessee,Tex-Texas,Va-Virginia, Wis-Wisconsin,WVa-WestVirginia. spendingto(i)H.prolificutnandtherestofsubsect. Centrosperma esis that H. kalmianum had a recent, post-glacial origin (from H. alongwithsubsectsPseudobrathydiumandSuturospertna,(vii) sub- prolificum).Theothersingle-speciesderivative(15.//. buckleyi)(v) sect.Brathydiumand(viii)subsect.Ascyrum.Thetransitionfrom 1. hasanareaintheCarolinasandGeorgia(theBlueRidgeMountains) H.frondosumto2.H.prolificumisgradual,consistingessentiallyof thatiswhollywithinthatof//,prolificum.Thespeciatingfactorsfor reductionsinsizeofpartsandincreaseofvariation north-westward this dwarf straggling shrub with reductions in size and inflores- NW from Georgiatothe uplandsbordering thecentral Mississippi cence-branching would seemtobe altitude andexposure. basin; but there is a morphological 'gap' between these species, at The remainderofsubsect. Centrosperma (clades iii and iv) show least in the wild. The wide distributional range of2. H. prolificum several parallelisms, so that extreme members of each (7. H. includes acomparably wide range ofvariation, so that as many as tenuifoliumand8.H.lloydiiontheonehandand 11.//.brachyphyllum five clades (ii-vi) appear to have arisen directly from it. 3. H. on the other) have come to resemble one another, with resultant kalmianum (ii) is anorthern derivative in which reductions in size taxonomicconfusion.Adams(1959, 1962)resolvedthisconfusionas (overallandofmostparts)andinflorescence-branchingareaccom- regardstheU.S.species,andIhaveattemptedtoincorporatethetaxa paniedby a(secondary) increaseto5-mery intheovary.TheGreat from Cuba and Belize. Clade (iii) is relatively straight-forward. A Lakestypeofdistributionmaybeassociatedwiththeglacialnunatak southwardtrendfrom//.prolificumresulted intwotaxa, one north- in this region, i.e. the species may have reached its present area in eastern (5. H. densiflorum), the other south-western (4. //. & pre-glacialtimes. Utech Iltis(1970),however,favourthehypoth- lobocarpum). The reasons for treating these taxa as species rather STUDIES INHYPER/CUM 81 than subspecies are explained on p. 100. In both species there is a subsect. Centrosperma (iv) forms the H. nitidum-H. fasciculatum reductioninsizeofflowerandleafandanincreaseinflowernumber. group, which comprises two subgroups: the H.fasciculatum group In H. lobocarpum, these changes are accompanied by a marked (Spp. 12-14), confined tothe American lowland mainland from N. tendency towards a 5-merous ovary and lobed fruit, whereas in H. Carolina to Mississippi, and the H. nitidum group (Spp. 9-11), densiflorumtheyarenot. H. lobocarpumis mainly intheuplandsto having a similardistribution but extending into Louisiana, western the west ofthe lower Mississippi; H. densiflorum has a two-armed CubaandBelize.Theprimitiveformsof9.H. nitidumwouldappear distribution:coastalplainfromNewYorktoS.Carolinaandalongthe to be in Cuba and Belize, but those of 13. H.fasciculatum are in westernsideoftheAppalachianMts.Butan'arm'of//,lobocarpum^ Florida.Theoverlappingareasandincompletemorphologicaldiffer- areaextendseastward inthe southto south-eastern S.Carolina; and entiation of the taxa in the H. nitidum group suggest that wherethe southernendoftheH. densiflorum areameetsthis 'arm', land-connectionsbetweenBelizeandFloridaviaCubaexistedfora incentralAlabama, someintermediates(hybrids?)occur.Anarrow- longtime. leavedformof//,densiflorumfoundinTennessee(H.interiorSmall) The remaining clade from 2. H.prolificum (Clade vi)comprises providesamorphologicallinktothenarrower-leaved6.H.galioides, subsect. Suturosperma, of which the lowest branch (Spp. 16, 17) which has acoastal-plain distribution (N. CarolinatoeasternTexas includes species that are morphologically somewhat intermediate. excludingpeninsularFlorida).Thisspeciesofrelativelywethabitats H.apocynifoliumandH.nudiflorum,whichhaveinflorescencesthat isecologicallydistinctfrom its largelyco-extensivereducedderiva- aremoreacropetallybranchedthanthoseof//,prolificumaswellas tive, 8. H. tenuifolium, a plant ofdry sandy habitats. Between the smallerflowersandbroaderleaves,formanothereast-westpairwith 'arms' of H. densiflorum'^ range there occurs 7. H. lloydii, a low, overlapping distributions: H. apocynifolium from Oklahoma and spreading, narrow-leavedderivativeofthatspeciesfromtheeastern TexastoLouisianawithoutliersontheFlorida-Georgiaborder, //. South Appalachian foothills. The remaining derivative clade of nudiflorum from eastern Texas to Virginia excluding Louisiana, Sects 21. Webbia and 22. Arthrophvllum Relationships Distribution and Characters a) b) nanum var. prostratum vacciniifolium 4b 5 s Turkey 4d pamphylicura / ? O nanum var. nanum rupestre canariense pal margin contiguous \ sprt ne trop. Africa style bases revolutum ssp. revolutum Fig.4 Sects21. Webbiaand22.Arthrophvllum.a)Relationshipsandchromosomenumber(2n).b)Distributionandlimitsofcertaincharacters.Forkeyto annotationsseeFig. 3(p. 80). 82 N.K.B. ROBSON Sects 23. Triadenioides, 24. Heterophylla. 25. Adenotrias Relationships aegypticum ssp. aegypticum aciferum IC aegypticuw ssp. webbii 1L aegypticum ssp. maroccanum 20 N dogonbadanicum I ssp. smithii socotranum Fig.5 Sects23. Triadenioides,24.Heterophyllaand25.Adenotrias.Relationshipswithinsectionsandwithspeciesofsect. 1 Campylosporus,showing chromosomenumbers(2n). where it is apparently extinct. The rest of the clade consists of a easternTexas),butitalsooccursdisjunctlyalongtheEasternCordillera southern branch (18. H. cistifolium in the Coastal Plain from N. inMexico,Guatemalaandthe HondurasRepublic. Inaddition, itis Carolina to Louisiana including Florida, 19. H. microsepalum in foundinthemainislandsoftheGreaterAntillesandintheBahamas Florida)andanorthernone(20.H.sphaerocarpuminthecentraland andBermuda.ArecordfromtheAzoressuggestthatitisarelatively upper Mississippi valley 'giving rise to' the herbaceous 21. H. recentarrivalthere;butwhetheritcamebynaturalextensionofrange adpressum (north-eastern) and 22. H. ellipticum (northern). or with human assistance is not clear. Overlapping the northern To return to the clades directly related to 1. H. frondosum, in marginoftherangeoftheerect29a.subsp.hypericoidesisthatofthe subsect. Bmthydium 23. H. myrtifolium (Clade vii) has smallerbut morespreading29b.subsp.multicaule(OklahomatoMassachusetts); broadleavesandamoreacropetallydeveloped,morewidelybranch- andinHispaniola(DominicanRepublic)thereisaprostrate,almost inginflorescencethanH.frondosum,anditsdistribution(Georgiato herbaceousform(29c. subsp.prostration). Mississippi) is to the south-east and distinct. The derivative 24. H. dolabriforme, with narrowerleaves and more unequal sepals, hasa Sects 21. Webbia and 22.Arthrophyllum smallrelictareatothenorth-westcentredinKentuckyandTennessee. Foicncaulpliy,esinaCwliaddeevairieia(ssuobustehcwt.a/rUdcyorfMa/nl)itnehefvraormiasboleutHh.-ecarsutxe-rannOdkrleaa-e Characters and variation (Fig. 4a, b) homatoNewYork(LongIsland).Threeofthederivativespeciesoccur Sects Webbia and Arthrophyllum form a monophyletic group di- wholly(27.H. edisonianum,28.H.suffruticosum)orlargely(26.H. rectlyrelatedtosect.Campylosporus.Aswillbeexplainedonp.135, tetrapetalum) within thatarea, H. tetrapetalum being found also in I now regardthenearestrelativeofH. canariense(sect. Webbia)to westernCuba.Theveryvariable29.H.hypericoides,however,hasa benot//, roeperianum(asinRobson, 1985: 166-168,ff. 1-3)but//. much wider distribution and is divided into three subspecies. The revolutum subsp. revolutum, more specifically the relatively broad- subspeciesmorphologicallynearesttoH. crux-andreae,29a. subsp. leaved form of that species that occurs sporadically in Ethiopia. hypericoides,occupiesalmostthe sameregionintheU.S.A. asthat From it, H. canariense differs inter alia in having '3' stamen species (Delaware and Maryland west to eastern Oklahoma and fascicles, a3-merous ovary with divergent styles, noblackglands,

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