1917] VESTAL—FOOTHILLS VEGETATION . 357 
CLASSIFICATION OF FOOTHILLS HABITATS 
Xerophytic neg (the general condition of summits and side-slopes) 
Rocky habita 
Craggy pe and rock-walls (see figs. 2, 3) 
Rock-strewn detritus slopes 
Rock-talus, usually less stable than preceding 
“Granite-gravel” habitats 
Compacted granite-gravel floors and side-slopes (see fig. 3) 
Loose granite-gravel floors, washes, and talus (= gravel slides) 
Fine-soil habitats 
ed-soil floors and detritus-slopes (fine soil with imbedded and superficial 
rock fragments of various sizes) 
Fine-soil floors and detritus-slopes (infrequent) 
Less xerophytic habitats (valleys and steep slopes, etc., relatively local) 
Less xerophytic side-slopes coined? north-facing, cantly of considerable 
gradient, and best developed in valleys) 
Mesophytic ravine habitats 
Narrow ravines (best developed in small side-canyons, especially on the 
south side of eastward-flowing main streams) 
Canyon-bottoms (the wider bottoms of the larger canyons are sometimes, 
however, exposed and xerophytic) 
Seepage and dripping areas (infrequent and small) 
Stream-side habitats (with usually constant supply of soil moisture, but 
widely varying atmospheric conditions 
Synopsis of plant associations 
The following synopsis is aimed to give in perspective the 
distinguishing characters of the plant communities of the foothill 
region. It is based upon whatever features of the particular com- 
munity seem most distinctive and appropriate: growth-form, 
moisture relations, physiographic, geographic, and successional 
relations. 
CLASSIFICATION OF FOOTHILLS ASSOCIATIONS 
iations generally primitive in character: the first vegetation of new or 
adivoubic & habitats, usually in rocky or gravelly situations; vegetation 
open and sparse, generally xerophytic 
Plants lichens; on rock surfaces, either on craggy summits, knobs, and 
rock-walls, or on loose boulders......-......0.00¢e0e Lichen associations 
Plants paella sticg in rocky or detrital situations, soil of variously 
ani tg instr shrubs; of nate local and temporary occurrence; 
frequent in areas recently ieee ae sess, + Sumac association 
Dominant a Faia bie) punted coercieton 
