Nov. 1905. | ACACIAS IN VARIOUS PLACES. 131 
In South America I found that an acacia, A. cavenie 
(332, Chile), is or used to be the dominant plant over a 
considerable part of the Central Chilian valley, i.e, from 
[tata to Chillan. 
This is the transitional zone between the temperate flora 
of South Chile and the horrible desert of Atacama and 
Tarapaca, where the only plant found by Darwin was a 
lichen growing on mule-bones. 
In the locality where this acacia once existed in great 
numbers there is a very long dry season, and probably there 
is underground water. The Guanaco used to be common all 
over this part of Chile, so that the stout spines are not 
unexpected. 
On the other side of the Andes, near Mendoza (Argentine) 
there is an association of thorny shrubs, the Chanar (Gouwrliea 
decorticans), which, though not an acacia, seems to have a 
similar habitat. 
In Brazil the “ Carrascos,” composed of Acacia dumetorum, 
are thickets of thorn-shrubs sufficiently open to allow a 
horseman to pass in any direction (Schimper, /.c., p. 282). 
In Nicaragua A. spherocephala and A. cornigera are well 
known on account of the ant-police which they support, but 
I have not been able to satisfy myself as to their country. 
In Northern Mexico, Arizona, and Texas, the extensive 
chaparal (Prosopis glandulosa and P. pubescens) is an 
acacioid thorn-scrub association, and acacias occur also in the 
sub-tropical steppes of Mexico, but here again I have not 
definite data (Schimper, /.c., p. 509). 
I must not omit the Island of Socotra, where the acacias 
socotrana, Balfour fil. (on plains near the sea on north side of 
island) and A. pennivenia, Schweinfurth (Tamha), as well as 
Dichrostachys dehiscens, Balf. fil. (Kadhab and Hadibu plains) 
occur, as well as an acacia undescribed ! (plains near Galonsir). 
These plains have been described by our President as part of 
the Arabo-Saharan desert. 
I think that this very imperfect sketch of the distribution 
of acacia shows that it is the commonest and most character- 
istic constituent of desert-bordering associations both in 
tropical and sub-tropical countries.. They are often the 
dominant plant in thorn-scrubs, thorn-woods, and light woods 
1 Balfour, “ Flora of Socotra.” 
