27 
illttsir ated by the South African Flora. 
notable. The divergence is always considerable in the case of the Australian 
and South African and South American connexions. The species and even 
the genera are usually distinct. In general the distribution of the bulbous 
Monocotyledons can be explained equally well by divergent invasion from 
the northern hemisphere as by land connexions in the southern. 
As regards the South African species and their present-day distribution, 
practically all the large genera show relatively wide-ranging species around 
which relatively rare endemics may be grouped ; or allied species in neigh- 
bouring areas or under different ecological conditions ; or variable species 
in the process of breaking up. Being of a rather uniform ecological type, 
however, the examples are not quite so striking as when a xerophytic, 
widespread, shrubby species among the Dicotyledons is connected with 
a mesophytic forest species. The bulbous Monocotyledons nearly all 
belong to early stages of the plant succession. 
Among the Liliaceae, the genus Asparagus is more varied in its 
ecological behaviour, and widespread species may be paired with rare 
endemics in a very striking way, e. g. A. declinatus and A. Macowani ; 
A. stipulaceus and A. Burchellii ; A. striatus and A. erectus\ A. sarmentosus 
and A. oxy acanthus ; A. f ale atus and A. Sprengeri ; A. aethiopicus and 
A . myrioclados ; A. medioloides and A. Krausii and A. volubilis. The large 
genus Aloe similarly supplies numerous examples of the working of our 
general principles. 
Orchidaceae . 
There are eighteen endemic genera, of which one, Huttonaea , is eastern 
and the rest mainly or entirely south-western. Another twenty-eight genera 
are also found in tropical Africa, and these have invaded South Africa to 
a greater or less extent from north and east towards the south-west. For 
details concerning the distribution of the genera and other Monocotyledonous 
families, Schonland should be consulted (30). 
Restionaceae . 
As is well known, this is another of the typically south-western families, 
only two species (one each of Restio and Leptocarpus ) being found in Natal. 
The family may, however, probably be connected with the Eriocaulaceae, 
which are much more widely distributed in the tropics of both hemi- 
spheres. 
Gramineae. 
The 500 odd species of grasses in South Africa fall naturally into two 
distributional groups, the south-western being distinctly separated from the 
rest. The south-western grasses are temperate in their affinities, the eastern, 
northern, and western are tropical. Eighty or ninety of the south-western 
species are endemic. The chief genera are Danthonia , P entaschistis , 
Pentameris , Achneria , Avenastrum , Brizopyrum , Lasiochloa , Ehrharta. 
Though the temperate tribes are thus mostly concentrated in the south- 
