Cape plants: corrections and additions to the flora. 1

Abstract

Comprising an area of ± 90 000 km:, less than 5% of the land surface of the southern African subcontinent, the Cape Floristic Region (CFR) is one of the world’s richest areas for plant species diversity. A recent synoptic flora for the Region has established a new base line for an accurate assessment of the flora. Here we document corrections and additions to the flora at family, genus and species ranks. As treated in Cape plants, which was completed in 1999. the flora comprised 173 families (five endemic), 988 genera (160 endemic: 16.2%), and 9 004 species (6 192 endemic: 68.8%). Just four years later, a revised count resulting from changes in the circumscriptions of families and genera, and the discovery of new species or range extensions of species, yields an estimate of 172 families (four endemic), 992 genera (162 endemic: 16.3%) and 9 086 species (6 226: 68.5% endemic). Of these, 948 genera and 8 971 species are seed plants. The number of species packed into so small an area is remarkable for the temperate zone and compares favourably with species richness for areas of compa­rable size in the wet tropics. The degree of endemism is also remarkable for a continental area. An unusual family compo­sition includes, in descending order of size, based on species number. Asteraceae. Fabaceae. Iridaceae. Ericaceae. Aizoaceae, Scrophulariaceae. Proteaceae. Restionaceae, Rutaceae. and Orchidaceae. Disproportionate radiation has resulted in 59.1% of the species falling in the 10 largest families and 74.6% in the largest 20 families. Thirteen genera have more than 100 species and the 20 largest genera contribute some 31.5% of the total species number.