A checklist of the plants of Mahwaqa Mountain, KwaZulu-Natal

A checklist o f the plants of Mahwaqa Mountain. KwaZulu-Natal, is presented. The list includes 1 030 indigenous and naturalized flowering plants and ferns. Comparisons are made with the floras of KwaZulu-Natal (Ross 1972). the Cape of Good Hope Nature Reserve, Cape Point (Taylor 1985). the southern Natal Drakensberg (Hilliard & Burtt 1987). the Amatolas (Phillipson 1987). the Langeberg (McDonald 19991 and Umtamvuna Nature Reserve (Abbott et al. 2(MX)). It is hoped that the publication of this list w ill contribute towards the recognition of the area as a natural heritage site.


INTRODUCTION
The Grassland Biome covers 343 (KM) km: or 16.5% of the land area in South Africa and supports the greatest human population densities and the highest levels of agricultural utilization on the subcontinent, consequently it is under considerable conservation threat. Only 1.12% of South African grasslands are currently conserved despite the fact that they contain high levels of floristic diversity (Rutherford & Westfall 1994). Some idea of the heterogeneity of the Grassland Biome can he gleaned from the fact that it accommodates 25 of A cocks's veld types. Comparative aspects of biodiversity are limited by size disparity in the geographic areas under considera tion. However, it is pertinent to mention that our collec tions from this single mountain exceed 1 (MX) spp. and the whole of the Cape Peninsula was estimated to sup port in the region of 2 622 spp. (Adamson & Salter 1950).
Mahwaqa Mountain falls into the Zambezian Subregion which boasts a number of endemic genera, most o f which are concentrated in Angola and in the Drakensberg system, in fact the latter is characterized by a high percentage o f local endemics (Takhtajan 1986: Hilliard & Burtt 1987: Cowling & Hilton-Taylor 1997. The mountain falls under Acocks's (1988) Veld Type 44a. Highland Sourveld. About 51.3% o f this veld type occurs in Kw aZulu-Natal and. of this, 8.7% is protected. Unfortunately, the great majority of conserved vegeta tion falls within a single reserve. Natal Drakensberg Park, and consequently geographic diversity is under represented (Scott-Shaw et al. 1996). To address this problem it is essential to have information pertaining to the floristic diversity in geographically distinct areas. In this way the conservation importance of such areas, under the threat of agricultural exploitation, can be assessed in some detail. Drakensberg Gardens between 29° 40'S and 29° 50'S lati tude and 29° 38'W and 29° 4 0 'W longitude. The moun tain is almost completely surrounded by cultivated land, w ith the Mossbank Plantation to the south and farmlands to the north, east and west. This situation is dynamic w ith an ever increasing number of farmers planting exotic timber.
The mountain lies within Turner's (Philips 1973) physiographic region-Bulwer Block-with an altitudinal range of 1 700 m to almost 2 000 m above sea level. The highest point of Mahw aqa Mountain (2 075 m) com prises a basalt cap overlying Clarens Sandstone, with yellow and red apedal. freely drained, dystrophic soils, which have a tendency to be highly leached (Van Oudtshoom 1992).
Mahwaqa is in the summer rainfall region of south western KwaZulu-Natal, with peak precipitation between November and March (Schulze 1982). The summit of the mountain is largely grassland, but intact patches of indigenous forest occur in the sheltered areas, from which tire is excluded, and the largest of these is Inkelabantwana Forest.
The vegetation on a large portion of the mountain is fairly pristine and torms part of a biosphere reserve. Extensive collections have been made by M.A. Rennie on Sunset and Glengaritf Farms which are adjacent to the biosphere reserve and reach a maximum elevation of 1 985 m.

MATERIALS AND METHODS
Provisional species inventories for the area were obtained from M.A. Rennie and species lists (no vouch er specimens) were provided bv R. Scott-Shaw and K. Cooper. In most instances this information was verified and supplemented by a study of herbarium specimens in the Natal University Herbarium (NU) and by a literature search. PRECIS [National Herbarium. Pretoria (PR E i Computerised Information System] was consulted and the relev ant data w as extracted and cross-referenced w ith voucher specimens at PRE. For the most part, the arrangement of the checklist conforms to the Englerian system, followed by De Dalla Torre & Harms (1907) and Arnold & De Wet (1993). The liverworts follow Perold (1999). Naturalized weeds are marked with an asterisk (*).
There are 45 pteridophytes comprising 4.4% of the mountain's flora. The ratio of monocotyledons to dicoty ledons on Mahwaqa is 1: 2.1. Ten families of flowering plants are very well represented and collectively constitute over half (53%) of the total species (Table 2). Nineteen fami lies each contribute more than 1% to the total number of species, collectively accounting for 67% of the species. It is interesting to note that the diversity of pteridophytes is high at the family level but low at the species level. Conversely, the monocotyledons show a trend with proportional incre ments at the generic and species levels. This possibly indi cates a fairly low number of families rapidly speciating in conjunction with the spread of the Grassland Biome.
The floristics of many South African habitats are domi nated by the Asteraceae (Taylor 1985: Westfall et al. 1986: Hilliard & Burtt 1987: Van Wyk et al. 1988: Deall & Backer 1989. This family is also dominant on Mahwaqa Mountain (15.6%, Tables 2: 3). Asteraceae is represented by fewer species on Mahwaqa than in the southern Drakensberg, but are better represented on the Mountain than in KwaZulu-Natal as a whole (Table 3). This trend in the data was expected, as Asteraceae is the largest family in KwaZulu-Natal and its highest diversity occurs in the Drakensberg (Hilliard 1978). The family is characterized by speciation in the Grassland Biome, the major habitat on Mahwaqa Mountain. The higher species diversity recorded in the southern Drakensberg (Hilliard & Burtt 1987) probably reflects the recruitment of Cape elements in this region and the Amatolas and Langeberg show similar levels o f diversity (   Poaceae is the second most diverse family in the study area (Tables 2; 3), dominating in terms of biomass, as the mountain falls primarily within the Grassland Biome. Grasses also constitute one of the main contributors to the Natal flora (Hilliard 1978). Gibbs Russell et al. (1990) identified a number of endemic Drakensberg grasses, some of which occur on the mountain (Agrostis barbuligera var. barbuligera, Cxnodon liirsutus, Digitaria tricholaenoides, Helictotrichon longifolium, Merxmuellera stricta, Pentaschistis e.xserta, P. setifolia, Setaria obscura and Sporobolus pectinatus). The family is less speciose to the south and accounts for only 3% of the diversity on the Langeberg. where fynbos dominates ( Table 5).
The apparent disparity between Table 2 and 3 with respect to the position of the Fabaceae is the result of the Liliaceae s.I. being treated as a single entity in Table 3 and being reduced to its component families in Table 2. This modification allows direct comparison with Hilliard (1978) and Ross (1972) which deal with Liliaceae s.I. In Table 2, Fabaceae is fourth on the list of species contrib utors. Hilliard & Burtt (1987) state that Fabaceae is the    Table 3). The lower diversity of this family on the mountain is partly due to absence of tropical tree and shrub species in the elevated grasslands.
The disparity is borne out by comparison between Mahwaqa Mountain and Umtamvuna Nature Reserve (Table 5). Four endemics to the southern Drakensberg. Argyrolobium nigrescens, A. sericosemium, Indigofera woodii and Lotononis virgata, occur on the mountain.
The Orchidaceae is well represented in mountain flo ras of the eastern seaboard and is the third most speciose family on Mahwaqa Mountain (85 taxa) and the fourth most in the southern Drakensberg (83 spp.). Only two of the Mahwaqa species are narrow endemics, Huttonaea oreophila and Pterygodium cooperi. The diversity of orchids on Mahwaqa and in the southern Drakensberg is higher than in any of the compared areas (Tables 3-5).
Liliaceae s.I. contributes 5.8% or 60 spp. to the Mahwaqa flora (Table 3). which correlates closely with the family's importance in the southern Drakensberg (6.3% or 84 spp.) and for the flora of KwaZulu-Natal (247 species or 5.1%). When broken down into com po nent fam ilies (sensu Dahlgren et id. 1985) the H yacinthaceae is best represented in the southern Drakensberg with 34 species (Hilliard & Burtt 1987). This pattern is repeated on Mahw aqa Mountain w here 29 species of Hyacinthaceae occur (2.7%). The Asphodelaceae is also well represented on the mountain with 23 species compared w ith the 19 species listed by Hilliard & Burtt (1987) for the southern Drakensberg. In Kniphofia. a number o f species are outlined as narrow endemics by Codd (1968) and of these K. ichopensis, K. brachystachya and K. fibrosa occur on Mahwaqa Mountain. The area is also the northern limit of K. paniflora.
The Iridaceae contributes a large number of species (43 or 4%) to the Mahwaqa Mountain flora ( Table 2). The family has a peak of diversity in the mountains and winter rainfall areas of sub-Saharan Africa (Goldblatt 1983) ( Table 4). The Iridaceae is the seventh largest fam ily in the southern Drakensberg (65 or 4.9 %) (Hilliard & Burtt 1987) and similar levels of diversity are seen on the Langeberg (5%) (McDonald 1999). Five of the species recorded from Mahwaqa are endemic to the southern Drakensberg. Moraea hiemalis, M. unibracteata, M. carnea (Goldblatt 1986). Gladiolus panulus (Goldblatt & Manning 1998) and Hesperantha grandiflora (Hilliard & Burtt 1986).
Scrophulariaceae (including Selaginaceae) are impor tant in the southern Drakensberg where they constitute 5.9% of the species (Hilliard & Burtt 1987). On Mahw aqa the family is slightly less important, contributing 4.2% or 44 species which is comparable to that for KwaZulu-Natal at 3.6% (Hilliard & Burtt 1987). This diversity includes three narrowly distributed species, Manulea florifera, Nemesia silvatica and Diascia megathura.
The Asclepiadaceae. now included under Apocynaceae (Leistner 2000). display similar levels of diversity on Mahwaqa and in the southern Drakensberg (3.1% and 3.4% respectively), but these levels are considerably lower than the diversity in KwaZulu-Natal (Ross 1972). This is probably due to the exclusion of tropical and xerophytic species from the montane habitats. A number of mesic asclepiads appear to have speciated in the Natal Drakensberg and of these Aspidonepsis flava, A. reenensis, A. diploglossa and Schizoglossum elingue subsp. elingue have been recorded on the Mountain. A com par ison w ith floristic inventories to the south, show that the Asclepiadaceae are insignificant in their contribution to the flora of the Langeberg.
It is clear from the data above that M ahwaqa Mountain supports a highly diverse flora and is a strong candidate for long-term preservation. The area approach es the Amatola and the Langeberg Mountains in terms of its a-diversity despite being a fraction of the land area. In addition, a-d iv ersity is com parable to that of Umtamvuna Nature Reserve of the Pondoland Centre, which is renowned for its phytodiversity (Van Wyk 1990. 1994. The levels of endemism are considerably lower than those of the Langeberg and the Pondoland Centre although numerous southern Drakensberg endemics occur on the mountain.
One of the most insidious threats to the diversity of indigenous grasslands, is their invasion by opportunist seedlings from timber plantations. This threat is in the form of timber species, such as eucalypts and pines, as well as weeds from these plantations. Changing burning regimes, due to the high risk that fire poses to timber plantations, allow the proliferation of woody species which are intolerant o f fire. Pyrophytes, which constitute the bulk of the indigenous vegetation, are rapidly lost from these altered moribund habitats. The ubiquitous and irresponsible degradation of grasslands in KwaZulu-Natal is a serious indictment on agroforestry in the province. Hopefully the vegetation o f M ahwaqa Mountain will not succumb to the invasion of weeds and opportunist seedlings from the surrounding plantations.

SYSTEMATIC LIST
The angiosperm nomenclature is arranged according to Arnold & De Wet (1993). Leistner (2000). and species are arranged alphabetically within each genus. The nomenclature of Asparagaceae follows Fellingham & Meyer (1995). Synonyms in italics in brackets follow unpublished PRECIS lists.
Putative hybrids and subspecific taxa are excluded from the above tables but are included in the checklist. Most of the cited vouchers are housed in the Natal University Herbarium (NU), Pietermaritzburg and at the National Herbarium. Pretoria (PRE). Voucher slides of the bryophytes are housed at NU.