A Monograph of Monsonia L. (Geraniaceae)
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• -: ".••.?-•*•#:•>•-•-, I!-' .. MEDEDELINGEN LANDBOUWHOGESCHOOL WAGENINGEN • NEDERLAND 79-9 (1979) A MONOGRAPH OF MONSONIA L. (GERANIACEAE) BIBUOTHEEK LH. 0 2 NOV. 1979 OmV. TIJDSCHR. /inw H. J. T. VENTER Laboratory ofPlant Taxonomy andPlant Geography Agricultural University,Wageningen, The Netherlands Al 582.751.2 MEDEDELINGEN LANDBOUWHOGESCHOOL WAGENINGEN • NEDERLAND • 79-9(1979 ) A MONOGRAPH OF MONSONIA L. (GERANIACEAE) H.J. T. VENTER Laboratoryof Plant Taxonomy andPlant Geography, Agricultural University,Wageningen, The Netherlands Received 17-4-1979 Date of publication 14-9-1979 H. VEENMAN & ZONEN B.V.-WAGENINGEN-1979 CONTENTS Introduction 1 Geographical distribution 3 Ecology 4 Relationship to other genera 4 Relationshipo fth especie s(withi nMonsonia) 4 Citation ofspecimen s 5 Genus diagnosis 5 Keyt o the species 6 Speciesdescription s 10 1. M. angustifoliaE . Mey.e xA .Rich . 10 2. M. attenuataHarv . 18 3. M. brevirostrataKnut h 23 4. M. burkeanaPlanch ,e xHarv . 26 5. M. deserticolaDinte r exKnut h 32 6. M. drudeana Schinz 35 7. M. emarginata(L.f. )l'Herit . 39 8. M. galpiniiSchltr .e xKnut h 44 9. M.glauca Knut h 47 10. M, grandifoliaKnuth 53 11. M. heliotropioides(Cav. ) Boiss. 57 12. M. igneaSchin z 62 13. M. ignorata Merxm.& Schreiber 66 14. M. lanuginosaKnut h 69 15. M. longipesKnut h 72 16. M. luederitziana Focke& Schinz 77 17. M. natalensisKnut h 81 18. M. nivea(Dene. )Web b 84 19. M.parvifolia Schinz "0 20. M.praemorsa E .Mey .e xKnut h 94 21. Af. senegalensis Guill.& Perr . 98 22. M.speciosaL. '05 23. M. transvaalensisKnut h ''' 24. M. trilobataKer s 114 25. M.umbellata Harv. 117 Nomina nuda Species excluded '22 Acknowledgements 123 Bibliography T , f 126 Index ofname s INTRODUCTION The present publication isa monograph ofth e genus Monsoniamainl y based on a study of material from 39 herbaria from Southern Africa, Europe and America. Approximately 3000 specimens were examined. The investigation of theherbariu m materialwa ssupplemente d byfield studie so fsom eo fth especies . Pollen were, moreover, collected from all the species for examination with the scanning electron microscope. The Monsonia Species are rather uniform in morphology, both vegetatively and generatively, and therefore sound differential charactersar eseldo m present. There is, furthermore, so much variability within each taxon that distinction between speciesbecome seve nmor edifficult . Onlythroug h theaccessabilit y ofa large number of specimens distinctive patterns or combinations of characteris tics became clear, thus permitting the delimitation of the species. In the past much emphasis waslai d on a singlefeatur e asdistinctiv e characteristic between species, for example the number of flowers in an inflorescence. This resulted in inaccuracy and confusion, as was the case with the epithet'biflora' applied in a number ofcases . Leaf form is an important characteristic in the species of Monsonia.Th e va rious forms were identified and named according to the SYSTEMATICS ASSO CIATION COMMITTEEFO R DESCRIPTIVE BIOLOGICAL TERMINOLOGY(1962) . As far aslea fvenatio n isconcerned , four main typescoul d be distinguished, viz. i) pinnate venation - one midrib from the blade base branching along its length into lateral veins; ii) subpinnatevenatio n- asfo r pinnate,bu tth emidri ba tit sbas e accompanied bytw oo rmor elatera lvein swhic hare ,however ,les stha n halfa slon ga sth e midrib; iii) palmate venation - three or more about equal-sized main veins branching from theblade' s base; iv) subpalmatevenatio n - asfo r palmate,bu t themidri b largertha n the lateral veins, and these lateral, furthermore, more than half as long as the central vein. Different indumentum types arepresen t in theMonsonia species .Thes e types areidentifie d and named atth ehan d of LAWRENCE(1951) . Although someo fth e specieshav eonl ya singl eindumentum ,th emajorit y havea doubl e indumentum, especially on the stem (Fig.'s 1.5 and 4.3). Monsonia is conspicuously glanduliferous. In every species one or several kinds of glands have been observed. Stalked glands (Fig.'s 1.4, 1.5, 10.2 and 15.5),sessil egland s(Fig . 10.2),punctat eglands ,an dglandbase d hairs(Fig.' s 1.5 and 15.5)ar epresent . Thestalke d glands,however ,ar eno t uniform in structure, sincea columna r type(Fig . 15.5)an d an acicular type(Fig.' s 1.4 and 10.2)coul d be distinguished. The acicular type may be straight and erect (Fig. 10.2) or curved (Fig. 1.4). All these stalked types and even the hair of the glandbased Meded. Landbouwhogeschool Wageningen 79-9 (1979) 1 types are hollow and mostly filled with viscid exudate. The acicular stalked glandsma ya swel lb econsidere d asgland-tippe d hairs,bu t that may complicate the already difficult indumentum description even more. The present author thusprefer s 'stalked glands' to'gland-tippe d hairs'. Collections from thefollowin g herbaria werestudie d: A Cambridge, Massachusetts, U.S.A.: Arnold Arboretum. B Berlin,Germany : Botanisches Museum. BLFU Bloemfontein, Rep. ofSout h Africa: Herbarium of the University of theOrang e FreeState . BM London, Great Britain:Britis h Museum (Natural History). BOL Cape Town, Rep. of South Africa: Bolus Herbarium, University of CapeTown . BR Bruxelles,Belgium :Jardi n Botanique del'Etat . E Edinburgh, Great Britain: Royal Botanic Garden. FI Firenze, Italy: Herbarium Universitatis Florentinae, Istituto Botanico. G Geneve, Switzerland: Conservatoireet Jardin botaniques. GB Goteborg, Sweden:Botanica l Museum. GH Cambridge, Massachusetts, U.S.A.: Gray Herbarium. GRA Grahamstown, Rep. of South Africa: Herbarium of Albany Museum. J Johannesburg, Rep. ofSout h Africa: The Moss Herbarium, Univer sityo fth eWi twate rsrand . K Kew,Grea t Britain:Th e Herbarium and Library. KMG Kimberley: Rep. ofSout h Africa: Herbarium, Alexander McGregor Memorial Museum. L Leiden,Netherlands : Rijksherbarium. LINN London, Great Britain:Th e Linnean Society of London. M Munchen, Germany: Botanische Staatssammlung. MA Madrid, Spain: Instituto 'Antonio Jose Cavanilles',Jardi n Botanico. NBG Cape Town, Rep. of South Africa: Compton Herbarium, National Bot. Gardens. NH Durban, Rep.o fSout h Africa: Natal Herbarium. NU Pietermaritzburg, Rep. of South Africa: Herbarium of the Univ. of Natal. Paris, France: Museum National d'Histoire Naturelle, Laboratoire de Phanerogamic PEU Port Elizabeth, Rep. of South Africa: Herbarium University of Port Elizabeth. PRE Pretoria, Rep. of South Africa: Botanical Research Institute, Na tional Herbarium. PRU Pretoria, Rep. of South Africa: Schweickerdt Herbarium, Univ. of Pretoria. PUC Potchefstroom, Rep.o fSout h Africa: Herbarium ofth eUniversit y of Potchefstroom. Meded.Landbouwhogeschool Wageningen79-9 (1979) S Stockholm, Sweden: Section for Botany, Swedish Museum for Natural History. SAM Cape Town, Rep. of South Africa: South African Museum Her barium, National Botanic Gardens. SRG H Salisbury, Rhodesia:Nationa l Herbarium. STE Stellenbosch, Rep.o f South Africa: Government Herbarium. STE-U Stellenbosch, Rep. of South Africa: Herbarium of the University of Stellenbosch. UPS Uppsala, Sweden: Institute of Systematic Botany, University of Uppsala. US Washington, U.S.A.:Nationa l Herbarium, Smithsonian Institution. W Wien, Austria:Naturhistorische s Museum. WAG Wageningen,Netherlands :Laborator y ofPlan tTaxonom y and Plant Geography. WIND Windhoek, South WestAfrica : S.W.A. Herbarium. Z Zurich, Switzerland: Botanischer Garten und Institut fur Systema- tische Botanik der Universitat Zurich. ZULU Empangeni,Kwa-Zulu ,Rep .o fSout hAfrica : Herbarium ofth e Uni versity of Kwa-Zulu. Specimenscollecte d within thesam e1-degre egri d aregroupe d together in the specimen lists following the species descriptions. These grids are indicated as follows: for example 14S25Emean s 14°South-latitud e and 25° East-longitude. Twenty five species out of a total of 60 species and 8subspecie s or varieties whichwer edescribe d aremaintained . Nosubspecifi c taxaar edistinguishe d here. GEOGRAPHICAL DISTRIBUTION Monsonia occurs in Africa, Madagascar and South West Asia. The main centre ofdistribution , however, isSouther n Africa where2 0specie soccur , 17 of which are endemic to this region, viz. M. attenuate/, M. brevirostrata,M. bur- keana, M. deserticola, M. drudeana, M. emarginata, M. galpinii, M. grandifolia, M. ignorata,M. lanuginosa, M. luederitziana, M. natalensis,M. parvifolia, M. praemorsa, M. speciosa,M. transvaalensis, M. trilobata,an d M. umbellata. M. angustifolia,M. glauca and M. senegalensis are widely distributed in Africa, the first mentioned is also present in Madagascar and the last of these three is also represented inAsia'a s far east asIndia . M. igneaan d M. longipes areendemi c to eastern Africa, whilst M. heliotropioidesan d M. niveaar eendemi c to the deserts of northern Africa and Arabia, the first mentioned also occurring as far east as West Pakistan. Meded. Landbouwhogeschool Wageningen 79-9(1979) ECOLOGY The species of Monsonia inhabit a variety of niches. A number of them are foundi ndeserts ,th eNamib ,Sahara n andArabia ndeserts ,severa loccu ri nsemi - desert areas,whils t another groupinhabi t sub-tropical or tropical bushlands or grasslandswhic hma yb edr yo rmoderatel ymoist .A smal lnumbe r ofspecie sar e restrictedt ocool ,hig haltitud egrasslands .A fe wspecies ,i nparticula r M.angus- tifolia,hav ea wid eecologica l amplitude and areencountere d under avariet y of climaticconditions .On especies ,M. speciosa, isendemi c to the South Western Cape region of South Africa where