126 ACACIAS IN VARIOUS PLACES. (Sess. ox. 
covered, with everywhere scattered trees: one could see 
perhaps a quarter of a mile in every direction. I selected seven 
plants as characteristic of this grassy, tree-covered plateau. 
All of them were Leguminose (Albizzia fastigqiata and others). 
At this point the first step in the change from monsoon 
wood to acacia scrub had been taken, but to get the acacia 
pioneers, we should have been obliged to go much further 
to the north. , 
The district bordering the Sahara on the south is pre- 
cisely that of which we know very little, but it is at least 
likely that similar acacia woods are or were common all 
along the border of the Sahara. 
Somaliland is in some places a desert almost as devoid of 
vegetation as the Sahara itself. A transitional acacia and 
thorn-scrub region, with a long dry season, occupies a large 
area in British and German East Africa to the south of 
Somaliland. 
From Mombassa. to Kibwezi and Machakos I marched 
through this transitional zone. Acacias are exceedingly 
common and characteristic: they are, with succulent 
_Euphorbias and Dioscoreas, perhaps also the most impressive 
features of the flora. There is a great deal of variation in 
the character of this scrub. Sometimes the acacias and 
other trees are scattered and distant, whilst the ground 
between is almost bare of vegetation. In other places the 
trees are in close order: flowering plants, creepers, and 
grasses cluster round their stems, and a considerable under- 
growth springs up. Gnarled and twisted acacias of all 
sorts and sizes, with bright white bark and a very thin and 
naked appearance, are the most usual shrubs and trees. 
Grasses and sedges growing in small tufts are dotted over 
the ground between these trees, but only as an epen flora, 
for the soil can be distinctly seen. These grasses form no 
sward or turf: except immediately after the rains, they are 
dead, dry, and withered up. Occasionally a tiny gazelle or 
“paa” with large ears springs out of the thorns and vanishes 
down the path. A closer search reveals (or at least used to 
do so) quantities of game such as ostriches, zebras, giraffes, 
Clarke’s gazelle, etc. This district is in part the same as 
that described in Engler’s “ Pflanzenwelt Ost-Afrikas,” which 
is connected especially with German East Africa. There is, in 
