San Bernardino Distriet. 627 
gramma triangularıs and Pellaca andromedifolia. The last, hard to point 
of brittleness, is the only form in which leaves persist throughout the dry 
season. 
3. Canyon Formation. 
The most prominent feature of this formation is the presence of trees. 
With the exception of the few mentioned in the mountains, trees are restricted 
to this formation. Trees are not found in all parts of the canyons; but in the 
parts where they do grow they form groves. It is unusual to find isolated 
specimens. This social habit does not produce tall straight trunks. Usually 
the trunks are massive and the unbranched stock is comparatively short. The 
crown is always large and spreading. These canyon groves are formed almost 
entirely by two species, namely Platanus racemosa and Quercus agrifolia. It 
is as common to find groves consisting of either Ouercus or Platanus as it is 
to find both together. In the upper and narrower parts of the canyons, Acer 
macrophyllum and Pseudotsuga macrocarpa are frequent. Owercus chrysolepis, 
a member of the mountain scrub frequently wanders into the canyons and 
‚becomes arborescent. 
In the region not occupied by trees, we find numerous shrubs and ge The shrubs of 
the canyon formation are usually uneE than those of mountains and foothills and are more 
regularly branched. ncy is much more toward a mesophytic than a zerophytic type. 
e tende 
The branches are Be straight. The leaves are of medium size and varying shape. They are 
seldom entire and often compound. The characteristic forms are Eriodietyon tomentosum, 
Romneya Coulteri, Amorpha californica, Trichostema lanatum, Rosa californica, Mimulus gen. 
glutinosus, Photinia arbutifolia, Zauschneria californica, Pentstemon cordifolius. Climbing for 
are represented by Vitis californica and Rhus toxicodendron. In canyons which no longer Be 
oc. ; 
on the spreading rather than the erect habit and its joints are not more than half the size of 
the hill forms 
The herbaceous flora of the canyons is a large one but its composition does not vary as 
often or as regularly as that of the foothill. Many forms are typically mesophytie in nature, 
; E n 
Only one fern growns on the canyon floor, Pteris (Pteridium) aquilina. It is much smaller than 
when growing in moist open sandy situations. 
During the wet season shrubs about 2,5 meters high constitute nearly the entire vegetation 
of a River Bed Formation. In manner of growth these forms resemble the canyon shrubs. 
The leaves are, however, always entire and usually smooth. The major portion of this shrub 
growth is made up of Salix lasiolepis, S. laevigata, Baccharis viminea and Nicotiana glauca. 
During the wet season, herbs are uncommon and are restricted to the borders of the river beds. 
After the flow of water ceases (usually in April) many of the mesa herbs spread over the river beds: 
2. San Jacinto Territory. 
This interior territory differs from the coastal mostly in a negative way, the 
latter possessing fully one hundred species which do not extend into the et 
Among these are eight species of Atripler, five each of Chorisanthe an 
Phacelia, four each of Gilia and Antirrhinum, and three each of Astragalus, 
Calochortus, Cotyledon and Salvia. 
40* 
