246 IOWA ACADEMY OF SCIENCE Vol. XXIX, 1922 
Fig. 1. General view of Yosemite region. Vernal and Nevada Falls to the right 
halepense) and many others which occur in late summer. Except 
for the more or less fleshy leaved kinds the plants of the fields 
are dry. Barnyard grass, Johnson grass, crab grass and other 
plants of this type are green only near irrigated ditches. The 
foothills show only the dried remains of wild oat ( Avena fatua ) 
and tall meadow oat grass ( Arrhenatherum elatius ), Hordeum 
murinum and H. maritimum var gussonianum. Along the San 
Joaquin and its smaller tributaries the valley oak ( Quercus lo- 
bata), a beautiful tree with spreading pubescent branches, is fre- 
quent. The cottonwood ( Populus Fremontii) occurs along living 
streams and willows like the sandbar willow ( Salix fluviatilis ) , 
the black willow (S. nigra) and the arroyo willow (S. lasiolepis) 
as well as the box elder ( Acer negundo var Calif ornicum) and the 
ash ( Fraxinus Oregona), are more or less common. A difference, 
however, is observed in the foothills through which Merced river 
flows. The foothills here, as along all other streams of the Sier- 
ras, are more or less dry. Here may be found the Digger pine 
( Pinus Sabiniana) which usually forms a very thin stand. The 
large cones and thin gray foliage give the foothills a peculiar as- 
pect. Digger pine is frequently associated with the California 
buckeye ( Aesculus Calif ornica) and the western red bud ( Cercis 
occidentals) . Valley oak ( Quercus lobata) may still occur and 
with it the Wislizenus oak (Q. Wislizenii) . The Oregon ash 
( Fraxinus Oregona) occurs in the foothills along streams and 
was f<kmd at El Portal. In ascending the valley the aspect 
gradually changes, the bull pine ( Finns ponder osa) appears and 
