130 ACACIAS IN VARIOUS PLACES. [ Sess, cxx. 
by great flat-topped hills of recent sandstone, one sees how 
the dense thorn-woods and thickets which cluster round the 
base of the Boschberg open out into patches of wood which 
again scatter into isolated acacias and extend far out into the 
plain. Green river-woods accompany the windings of the 
Fish river, which also extends across the plains. 
On the banks of dry riverbeds in the Karoo itself, A. 
horrida (Doornboom), A. detinens (Wait-a-bit), and A. Giraffe 
are almost the only shrubs which can exist (Drude, “ Hand- 
buch der Pflanzengeographie”). Also in the deserts of 
Damaraland there are thick woods along some of the 
watercourses which are composed chiefly of acacias (A. 
detinens, var. biyjuga, A. hebeclada) (Schimper, “ Pflanzen- 
geographie,” p. 660). 
I have no exact data as to the occurrence of acacias in 
India, but A. planifrens seems to be a pioneer in certain 
deserts (¢/. Schimper, /.c., p. 290), and thorn-woods are common. 
Kurz (see Schimper, /.c., p. 407) describes in Pegu certain dry 
forests, Sha-woods, chiefly of Acacia catechu, which, from 
description, resemble very closely the East African 
thorn-bush. 
In Australia there is the Mulga Serub (4. anewra), Also, 
according to Tenison Woods (Drude, /.c., p. 497) the Brigalow 
Serub, on the western side of the coast mountains of 
Queensland, would seem from his description to be a similar 
association and similarly situated. The dominant plant is 
Acacia harpophylla (with <A. saligna and A. excelsa); the 
bluish-gray colour of its sickle-shaped leaves gives to the 
whole scrub a peculiar silver-gray sheen. This scrub is a 
fairly close thicket, and covers a large amount of ground. — It 
seems able to hold its own even on fairly good soil, for cattle 
do not eat the young shoots and devour the grasses (Proce. 
R.S. N.S. Wales, vol. vii. p. 565). The Kangaroo thorn, A. 
armata, is protected by thorns, but many of the Australian 
acacias rely upon the astringency of the bark, which has 
sometimes from 26 per cent. to 48 per cent. of tannin! One 
species, A. giaucescens, 18 poisonous, and a narcotic is obtained 
from it which is used by the natives to stupefy fish. So far 
as one can gather from descriptions, these Australian acacias 
fringe the inland desert in quite a typical way. 
' A, binervata, A. decurrens, A, dealbata, and other wattles. 
