International Excursion in America. 
329 
and is thus climatically different from “ true ” desert. Correspond¬ 
ingly the vegetation is more luxuriant and much more numerous in 
individuals than is the case in the typical North African deserts. 
It is the “dry bush steppe” of various Continental writers. The 
dominant growth-form is the fair-sized shrub, much bigger than the 
North African undershrubs, with small highly xerophilous and some¬ 
times deciduous leaves. The leading species are Larvea (Covillea) 
tridentata, Parkinsonia niicvophylla a nd Fouquieria splendens. Here 
and there the branched columns of the giant cactus rise far above 
the scrub and, locally, species of Opuntia and Echinocaclus occur in 
considerable numbers. Only in places do grasses or other herbs 
form anything like continuous ground cover. Along the channels 
and “washes” the mesquite (Prosopis) occurs abundantly and 
grows quite luxuriantly, together with species of Populus, Salix 
and Fvaxinus. 
Santa Catalina Mountains. 
On the afternoon of September 21st the party motored across 
the desert to the foot of the Santa Catalina range, on which the next 
few days were to be spent. The evening meal—taken at a camp at 
the base of the mountains amid a grove of giant cacti ( Carnegia )— 
was made quite luxurious by the excellence and variety of the food 
(which included a huge supply of ice-cream !), and just before 
sunset a start was made up the mountains for “ Oak Camp ” where 
the first night was to be spent. The lowermost slopes are covered 
by a magnificent stand of Carnegia mixed with Fouquieria. At a 
somewhat higher level these disappear and the first evergreen oak 
(Q. oblongifolia) appears, with Juniperas pachyphlcea, Arctostaphylos 
pungeus, Dasylirion Wheeleri, Nolina microcarpa , etc. The camp in 
“ Soldiers’ Canyon,” nearly 5,000 feet above the sea among the 
evergreen oaks and accompanying sclerophyll scrub, was reached 
long after dark. September 22nd was spent among the vegetation 
of this region, which is a transition between semi-desert and sclero¬ 
phyll vegetation. On the morning of September 23rd the further 
ascent of the range was undertaken. Among the evergreen oaks 
(Q. emoryi , Q. hypoleuca and Q. arizonica) the dwarf Finns cembroides 
(one of the “ pignon ” group, close to P. edulis and P. monophylla) 
appears, and about 5,500 feet it increases and permeates the whole 
open woodland. “ Manzanita Ridge” is covered with scrub among 
which Arctostaphylos spp. are conspicuous. Towards 6,000 feet the 
tall southern yellow pine (P. arizonica) comes in, and shortly 
afterwards P. chihuahuaensis. Here and there a few Douglas 
spruces and Pteridiuni aquilinum also appear. On the north-facing 
