S T R E L I T Z I A 34 The Apocynaceae of Namibia P.V. Bruyns Bolus Herbarium Department of Biological Sciences University of Cape Town Rondebosch 7701 Pretoria 2014 S T R E L I T Z I A This series has replaced Memoirs of the Botanical Survey of South Africa and Annals of the Kirstenbosch Botanic Gardens, which the South African National Biodiversity Institute (SANBI) inherited from its predecessor organisa- tions. The plant genus Strelitzia occurs naturally in the eastern parts of southern Africa. It comprises three arbores- cent species, known as wild bananas, and two acaulescent species, known as crane flowers or bird-of-paradise flowers. The logo of SANBI is partly based on the striking inflorescence of Strelitzia reginae, a native of the Eastern Cape and KwaZulu-Natal that has become a garden favourite worldwide. It symbolises the commitment of SANBI to champion the exploration, conservation, sustainable use, appreciation and enjoyment of South Africa’s excep- tionally rich biodiversity for all people. EDITOR: Alicia Grobler PROOFREADER: Yolande Steenkamp COVER DESIGN & LAYOUT: Elizma Fouché FRONT COVER PHOTOGRAPH: Peter Bruyns BACK COVER PHOTOGRAPHS: Colleen Mannheimer (top) Peter Bruyns (bottom) Citing this publication BRUYNS, P.V. 2014. The Apocynaceae of Namibia. Strelitzia 34. South African National Biodiversity Institute, Pretoria. ISBN: 978-1-919976-98-3 Obtainable from: SANBI Bookshop, Private Bag X101, Pretoria, 0001 South Africa Tel.: +27 12 843 5000 E-mail: [email protected] Website: www.sanbi.org Printed by: Seriti Printing, Tel.: +27 12 333 9757, Website: www.seritiprinting.co.za Address: Unit 6, 49 Eland Street, Koedoespoort, Pretoria, 0001 South Africa Copyright © 2014 by South African National Biodiversity Institute (SANBI) All rights reserved. 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S T R E L I T Z I A 34 (2014) iii Contents Abstract. 1 Introduction ................................................................. 2 Materials and methods . 4 Results . 5 Taxonomic account ............................................................ 8 Apocynaceae Juss. ............................................................ 9 RAUVOLFIOIDEAE Kostel. 10 CARISSEAE Dumort. ................................................... 10 Carissa L. ......................................................... 10 MELODINEAE G.Don .................................................. 12 Diplorhynchus Welw. ex Ficalho & Hiern ................................ 12 APOCYNOIDEAE Burnett . 13 BAISSEEAE M.E.Endress ................................................ 13 Baissea A.DC.. 13 NERIEAE Baill. ........................................................ 14 Adenium Roem. & Schult. ............................................ 14 Strophanthus DC.. 16 MALOUETIEAE Müll.Arg. ............................................... 18 Pachypodium Lindl. ................................................. 18 PERIPLOCOIDEAE R.Br. ex Endl. 20 Cryptolepis R.Br. (incl. Curroria Planch. ex Benth.) ........................ 20 Ectadium E.Mey. .................................................... 22 Raphionacme Harv. ................................................. 23 Tacazzea Decne. ................................................... 28 SECAMONOIDEAE Endl. 29 Secamone R.Br. .................................................... 29 ASCLEPIADOIDEAE R.Br. ex Burnett. 29 FOCKEEAE H.Kunze, Meve & Liede. 30 Fockea Endl. 30 MARSDENIEAE Benth. ................................................. 34 Gymnema R.Br. .................................................... 34 Marsdenia R.Br. .................................................... 35 Rhyssolobium E.Mey. ................................................ 35 Stigmatorhynchus Schltr. ............................................. 37 ASCLEPIADEAE (R.Br.) Duby ............................................ 39 Asclepias L. ........................................................ 40 Cynanchum L. (incl. Sarcostemma R.Br.) ................................ 42 Gomphocarpus R.Br. ................................................ 48 Microloma R.Br. .................................................... 51 iv S T R E L I T Z I A 34 (2014) Pachycarpus E.Mey. ................................................. 57 Pentarrhinum E.Mey. ................................................ 58 Pergularia L. 60 Periglossum Decne. ................................................. 60 Schizoglossum E.Mey. ............................................... 61 Schizostephanus Hochst. ............................................. 65 Sphaerocodon Benth. ................................................ 66 Tylophora R.Br.. 67 Xysmalobium R.Br.. 69 CEROPEGIEAE Decne. ex Orb. 69 Australluma Plowes ................................................. 71 Baynesia Bruyns .................................................... 72 Brachystelma R.Br. ex Sims ........................................... 73 Ceropegia L. 82 Duvalia Haw. ...................................................... 94 Hoodia Sweet ex Decne. 96 Huernia R.Br. ...................................................... 104 Larryleachia Plowes. 110 Lavrania Plowes .................................................... 113 Orbea Haw. ....................................................... 115 Orthanthera Wight. 122 Piaranthus R.Br. .................................................... 125 Quaqua N.E.Br. .................................................... 127 Stapelia L.. 130 Stapeliopsis Pillans .................................................. 136 Tavaresia Welw. .................................................... 138 Tridentea Haw. ..................................................... 140 Tromotriche Haw. 144 Acknowledgements ........................................................... 148 References. 149 Index ....................................................................... 151 S T R E L I T Z I A 34 (2014) 1 Abstract The Flora of Namibia is dominated by the most diverse in the extreme south of the country, families Poaceae, Asteraceae and Fabaceae. in the Rosh Pinah and in the Karasburg districts. Here, an account of the Apocynaceae, the sixth The distribution of each species is mapped and, largest family in Namibia, is presented. A total of for many genera, one species is illustrated with 153 species belonging to 46 genera are recorded line drawings. Lectotypes are selected for several as occurring naturally for the country and 19 of species. these species are endemic to Namibia, with two endemic genera. More than half of these 153 Keywords: Apocynaceae, Apocynoideae, species belong to the tribe Ceropegieae, with Asclepiadoideae, endemics, largest families, Na- the highly succulent group, the stapeliads, repre- mibian Flora, Periplocoideae, Rauvolfioideae, sented by 58 species. It is shown that the family is Secamonoideae. 2 S T R E L I T Z I A 34 (2014) Introduction The only account of the Flora of Namibia & Bruyns (2000) and APG III (2009) these now remains the Prodromus einer Flora von Südwest- fall into a single family, which is the sixth largest Afrika (Merxmüller 1966–1972). Much new infor- in Namibia (Table 1). mation has become available since the comple- tion of this work and revision of the ‘Prodromus’ Namibia is bounded on the west alongside is becoming ever more necessary. In an attempt the Atlantic Ocean by the Namib Desert, one of to initiate a Flora of Namibia, an account of the the most arid regions on Earth, and on the east family Apocynaceae for Namibia is presented by the semi-arid Kalahari ‘Desert’ (Simmons et al. here. 1998). Consequently the country is mostly arid to semi-arid. Over its surface area of 824 292 km2, The Apocynaceae is a medium-sized, cos- a total of 3 729 angiosperms have been record- mopolitan family of some 5 000 species with a ed. This is made up of 938 monocotyledons and preponderance of species in the tropics (En- 2 791 dicotyledons (Craven 1999), correspond- dress & Bruyns 2000). The family is well repre- ing to the widely known ratio of three dicotyle- sented in southern Africa generally, where over donous species to one monocotyledonous spe- 650 species are known (Germishuizen & Meyer cies (Goldblatt & Manning 2000). In contrast to 2003). the Cape Flora where petaloid monocotyledons dominate (Goldblatt & Manning 2000), in Na- In Huber (1967) the three families Apocyn- mibia the 938 monocotyledons are mainly non- aceae (6 genera, 10 species), Asclepiadaceae petaloid, with 551 species in the Cyperaceae (32 genera, 101 species) and Periplocaceae (5 and Poaceae alone and with the petaloid fami- genera, 9 species) were listed for Namibia (i.e. a lies Amaryllidaceae (43), Asphodelaceae (50), total of 43 genera with 120 species in the greater Hyacinthaceae (88), Iridaceae (36) and Orchi- Apocynaceae). With the arrangement of Endress daceae (20) contributing only 237 species