Nov. 1905. | ACACIAS IN VARIOUS PLACES. 127 
this book, the usual wealth of detail which is characteristic 
of German botanical work. Dr. Engler makes about ninety- 
five associations grouped under nine heads or formations, and 
in at least twenty of these associations acacias are found. The 
table which follows gives the titles of these acacia associations 
and the species which are recorded for each.» 
Now if one glances over this table, it must be confessed that 
it is exceedingly difficult to form any clear idea of the distinc- 
tions between and characters of these twenty associations. 
The first four belong to the coast, the next three are associations 
found below an altitude of 125 metres. Those marked v. a, 
b, and c.a are frankly acknowledged as transitional by Engler 
himself. My view, however, is that all these twenty associa- 
tions are transitional: the majority of them are variations ot 
an acacia-scrub region dependent on local differences in soil, in 
shelter, and in the amount of moisture. On the coast where 
the air is laden with moisture from the sea, one finds the 
usual thick evergreen wood with an occasional acacia on its 
outer edge (ii. C). This wood becomes more open in drier 
places where A. pennata is best able to take a prominent 
position (ii. D): further inland, where the influence of the 
sea moisture is less pronounced, the wood becomes a thick 
bush (iii. ¢); and in still drier places what Engler calls a 
thorn-bush thicket (ii. E and iii. 0). 
If a river cuts through this bush or thorn-scrub, its banks 
are covered by a strip of wood dependent on the river 
moisture, with a few acacias which are probably on the 
outside edge of the wood next the bush or thorns (ii. F). 
Much of the land is too dry even for thorn-bush thickets, and 
here comes in a pioneer acacia association, the so-called 
“orchard steppe,” from a somewhat fanciful resemblance of 
the scattered’ acacias to an orchard (iv. ¢). In rocky places 
and little broken hills where the moisture is in crevices of 
the rock, the acacias are often partly replaced by Euphorbias 
and other succulents (iv. /). 
At a height of about three thousand feet, this acacia region 
begins to shade off towards the monsoon wood, or, as Engler 
calls it, an “upper dry tropical wood,” which is characteristic 
of African plateaux at about this altitude. The transitional 
stages are a close steppe bush thicket (iv. a) and a steppe 
wood (iv. /) 
