216 Bews . — The South-east African Flora : 
Gymnosporia (Celastraceae). The oldest type of this genus, according 
to inflorescence and fruit characters, has no spines, and is represented 
in South Africa by such a type as G. acuminata , a small tree which occurs 
usually outside but sometimes inside forest. G. peduncularis is a closely 
allied large, mesophytic, forest tree. G. cordata , also near the ancestral type, 
is a coast forest species. A more recent type, with the inflorescence in 
clustered cymose panicles, is represented by G. buxifolia , a somewhat 
variable and widespread species all over South Africa. It is very spiny 
in the drier situations and illustrates the development, on the one hand, 
towards xerophytism. On the otl^r hand, the rare endemic, G. amaponden- 
sis , is a recent type with the fruit one-celled instead of three-celled. It 
is known only from the Egossa forest in East Pondoland and illustrates the 
development towards mesophytism. 
Any other large genus which is tropical and subtropical can be dealt 
with in exactly the same way as in the case of Euphorbia and Gymnosporia . 
Subtropical Grasslands. 
The flora of the great subtropical grassland areas consists of species 
which, unlike the trees and shrubs, are mostly wind-distributed, and the 
origin and migrations of the type as a whole are not so easily traced. The 
origin of the grasses themselves is also somewhat obscure. In the Bamboos 
the grass flower approaches nearest to the ordinary monocotyledonous type, 
and possibly they are the most primitive. The twenty-three genera of 
Bambuseae are mainly tropical with a tendency to extend largely into the 
mountains of the tropics, but they are not grassland types. The tropical 
and subtropical grasslands are dominated mainly by genera belonging 
to the tribes Andropogoneae and Paniceae, where the spikelets are much 
reduced and highly specialized, phylogenetically an advanced type. 
Aristida (Stipeae) is a large important genus adapted to drier sub- 
tropical and desert conditions. 
Temperate grasses, on the other hand, belong mainly to the tribes 
Aveneae, Festuceae, and Hordeae, with spikelets less specialized and con- 
taining usually numerous florets. This would seem to suggest that, wdth the 
exception of the Bamboos, the temperate grasses have retained more of the 
primitive floral characters than the tropical, but there is little agreement on 
the course of evolution in the grass flower, and the subject must for the 
present remain obscure. 
In South-east Africa the most distinctly tropical type of grassland 
is that of the coast-belt, where there is an admixture of species such as 
Pollinia villosa , Perotis latifolia , and species of Panicum , but the dominant 
species belong to the Andropogoneae, as in the high veld and low veld 
areas all over the eastern side. Species of Aristida , Eragrostis , and 
Sporobolus show adaptation to drier conditions and open formations. At 
