; ne cd AAA mo} saiurad Cd Physiotegical Botany. a 
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8 The ‘Sudan Region. 
This region includes Central Africa from 20°N, lak to 20 og. ; 
lat., as well as southern Arabia; and enjoys, in general, a re- ic a 
Eohiae rain only when the rays of the sun strike vertically 
downwards, remaining at other times under the influence of _ a 
the dry trade-winds. Growth is therefore possible only asan 
occasional phenomenon ; and the prevalent character of the 
vegetation is that of the savannahs. Copious dew and sharp ™ 
changes of temperature contribute to render the climate ofthis 
region extremely ill-adapted for the immigration of foreign 
\ 
forms; so that the aboriginal fauna and flora have been © 
preserved in their primitive aspect. A characteristic feature | se 
is the gigantic Grasses, often 6 or 7 metres high ; peculiar to ‘oe 
it are the enormous stems of the baobab and leaves of Wusa ee 
Lnsete. Among the more important useful plants are the 
tamarind, the fig-sycamore, the palms, especially the doom | “i 
palm and the oil palm £/aeds guineensis, and the succulent and 
poisonous arborescent Euphorbias. Acacias and thorny 
shrubs are generally distributed. A not inconsiderable por-. 
tion of the Sudan flora has migrated into Upper Egypt. ae 
South Arabia was at one time treated as a separate region, " 
on account of its balsamic vegetation. 
BRP Ss 
9. Zhe Kalahari Region. 
The Kalahari region extends along the Atlantic coast of. a 
Africa from 20° to 29°S. lat. It is altogether destitute of 
water, and forms a connecting link between deserts, savannahs, » 4 
and steppes covered with shrubs ; and has no oases witha 
settled population, but is tenanted only by wandering nomads. 
Peculiar to this region is the remarkable Wedwitschia (see — 
p- 338); and the most prominent members of the scanty — 
flora are spiny Acacias and other shrubs which almost | aa 
tirely impede locomotion, a number of bulbous and a 
_ plants, Grasses, and the aout African water-melon, pais) Te © 
are no palms. a 
