VEGETATION OF THE SANTA CATALINA MOUNTAINS. 27 
arroyos are Rhus trilobata, Baccharis emoryi, Erythrina flabelliformis, 
Bouvardia triphylla, Amorpha californica, Fendlera rupicola, Morus 
celiidifolia, and the climber Vitis arizonica. 
On the flood-plains of the larger cafions in the Lower Encinal may 
be found the lowest examples of several species which become common 
in the forested region of the mountain, and these are indeed the lowest 
members of the forest flora, if aquatics are excepted. At 4,900 feet 
Ceanothus fendlert and Prunus virens are both to be found, growing 
not only on a flood-plain but in the shade of evergreen oaks. Berberis 
wilcoxtt is found at 5,200 feet growing in shade near a constant spring, 
and Rhamnus ursina is infrequent at 5,000 feet near streamways. 
During the mid-summer there is an abundant stand of herbaceous 
perennials and ephemerals on the flood-plains of the Lower Encinal, 
giving them a much closer carpet of vegetation than is to be found on 
the adjacent slopes. Abundant and characteristic among them are: 
Artemisia sp. Euphorbia crenulata. 
Asclepias tuberosa. Gymnolomia multiflora. 
Brickellia californica. Hymenothrix wrightit. 
Castilleja integra. Malvastrum sp. 
Chameccrista leptadenia. Monarda pectinata. 
Comandra pallida. Solanum douglasit. 
Cordylanthus wrightit. Solidago sparsiflora var. subcinerea. 
Crotalaria lupulina. Sporobolus confusus. 
Diodia teres. Stachys coccinea. 
Eriocarpum gracile. Stenophyllus capillaris. 
THE UPPER ENCINAL. 
During the ascent from 5,000 to 6,000 feet the most notable change 
in the vegetation is the gradual increase in the density of the stand of 
evergreen trees and shrubs (see plates 18, 19, and 20), a change which 
forms the chief distinction of the Upper Encinal from the Lower 
Encinal. Quercus emoryi and Quercus arizonica are still the dominant 
trees, while Pinus cembroides and Juniperus pachyphlea are somewhat 
less common. Arctostaphylos pungens and Garrya wrighiti are the most 
common of the larger shrubs and Mimosa biuncifera of the smaller ones. 
Dasylirion wheelerit, Nolina microcarpa, and Agave palmeri remain 
abundant, at least on southern slopes, up to 6,000 feet and Agave 
schottii remains common up to its upper limit at that elevation. With 
the increasing abundance of the oaks, however, these semi-desert 
species as well as the cacti become infrequent and are confined to the 
summits of ridges and the crevices of rocks. 
On steep north slopes, between 5,300 and 6,000 feet, many almost 
pure stands of Pinus cembroides are to be found and also the lowest 
individuals of Quercus reticulata, here a low-branched tree of 20 feet 
in height. Pinus chihuahuana first appears at about 5,900 feet on 
south slopes, being the only one of the trees which is not found at 
much lower elevations on north slopes than on south ones—indeed it 
is not common on north slopes at any elevation. 
