Biological Journal of the Linnean Society, 2006, 87, 27–43. With 7 figures © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 27–43 27 Blackwell Science, LtdOxford, UKBIJBiological Journal of the Linnean Society0024-4066The Linnean Society of London, 2005? 2005 871 2743 Original Article AN OVERVIEW OF THE CAPE GEOPHYTES s. PROCHEs ET AL . *Corresponding author. Present Address: Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa. E-mail: sproches@sun.ac.za An overview of the Cape geophytes SERBAN PROCHES 1* , RICHARD M. COWLING 1 , PETER GOLDBLATT 2 , JOHN C. MANNING 3 and DEIRDRÉ A. SNIJMAN 3 1 Department of Botany and Terrestrial Ecology Research Unit, University of Port Elizabeth 6031, South Africa 2 A. Krukoff Curator of African Botany, Missouri Botanical Garden, PO Box 299, St. Louis, Missouri 63166–0299, USA 3 Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, South Africa Received 7 May 2004; accepted for publication 1 February 2005 The Cape Region (here treated as the winter rainfall region of southern Africa, thus including fynbos, renosterveld and succulent karoo vegetation) is the world’s foremost centre of geophyte diversity. Some 2100 species in 20 families have been recorded from this area, 84% of them endemic. The most important families, with more than a hundred geophyte species each, are Iridaceae, Oxalidaceae, Hyacinthaceae, Orchidaceae, Amaryllidaceae and Asphodelaceae. Although southern Africa does not appear to have been the main diversification centre for the plant orders with high- est geophyte representation (Asparagales and Liliales), it represents an active centre of transition to geophytism, such transitions having occurred independently in numerous plant groups, often followed by rapid speciation. Sev- eral Cape geophyte groups have consequently expanded across Africa to the Mediterranean Basin, and possibly to other winter rainfall regions. Remarkably high local species diversity in renosterveld vegetation, even in relatively homogeneous environments, suggests that pollinator specificity and phenology play an important role in niche par- titioning. However, character diversity is also high in storage organs and leaves, and this could account for the high species diversity values recorded at larger spatial scales, especially across environmental gradients. Long-term climatic stability, combined with topoclimatic and edaphic diversity and regular fire occurrence, is likely to be responsible for the remarkable geophyte diversity of the Cape, as compared to other mediterranean-climate regions. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 27–43. ADDITIONAL KEYWORDS: bulbs – corms – morphological plasticity – phylogenetic constraints – rhizomes – tubers. INTRODUCTION Mediterranean climates are well known for their remarkable plant diversity (Cowling et al., 1996), and the high numbers of geophytes they harbour have long been noted (Raunkiaer, 1934). The geophyte floras of some of these regions have been the subject of taxo- nomic and ecological reviews (e.g. south-western Aus- tralia: Pate & Dixon, 1982; Parsons & Hopper, 2003; California: Rundel, 1996; Chile: Hoffmann, Liberona & Hoffmann, 1998). The Cape Flora of South Africa is, however, by far the richest in geophyte species (Fig. 1), and while Cape petaloid monocots have recently received a popular review (Manning, Goldblatt & Snij- man, 2002), a comprehensive taxonomic, ecological and evolutionary assessment for the Cape geophytes is still lacking. A number of recent monographs (e.g. Goldblatt, 1986, 1989; Marais, 1994; Perry, 1994; Goldblatt & Manning, 1998; Linder & Kurzweil, 1999) clearly indi- cate that good taxonomic information has been accu- mulated, at least as far as some large genera are concerned. These are mainly genera of horticultural importance, with many species now being cultivated worldwide. However, significant discoveries continue to be made even in such groups, including the recent discovery of a new Clivia near Nieuwoudtville, hundreds of kilometres from the closest previously Downloaded from https://academic.oup.com/biolinnean/article/87/1/27/2691597 by guest on 29 December 2022