( 301 ) eth | H 
problems have been obtained from Coville’s “Botany of the Death 
Valley Expedition,” Parish’s “Sketch of the Flora of Southern 
California,” and Hall’s “Survey of San Jacinto Mountain,” as 
well as from Merriam’s paper dealing with his system of life zones, 
which latter I have adopted. 
Acknowledgments are most heartily given to the following 
persons for the loan of material, or for assistance in determining 
questions of taxonomy and nomenclature: Dr. B. L. Robinson, 
Mr. F. V. Coville, Dr. J. N. Rose, Dr. J. K. Small, Dr. P. A. Ryd- 
berg, Dr. H. M. Hall, Mr. S. B. Parish, Dr. A. Davidson, Mr. 
W. F. Wight, Mr. C. R. Ball, Mr. P. L. Ricker, Mrs. K. Bran- 
degee and Miss M. A. Day. 
To Professor W. R. Dudley, who has courteously given much 
time and valuable assistance, and through whose advice and en- 
couragement I undertook the study of the southern California flora, 
and to Dr. N. L. Britton, who has given valuable aid in carrying 
on these studies, is due whatever merit this paper may possess. 
INTRODUCTION 
PHYSIOGRAPHY 
Southern California is the name popularly applied to that part 
of the State of California which lies south of Point Conception 
and the Tehachapi Mountains, a territory lying between 32° 35’ 
and 35° 45’ north latitude, and extending from the 37th to the 
43d meridian west. Its western boundary is the Pacific Ocean, 
its southern Lower California, and its eastern the Colorado River, 
which separates it from Arizona. On the north the boundary 
is formed by the crosss ranges which break up the general trend 
of the Coast Ranges and the Sierra Nevada. Its line extends 
from Point Conception eastward along the Santa Ynez Mountains, 
Mount Pinos, and the Tehachapi Mountains to the southern ex- 
tremity of the Sierra Nevada, thence eastward to the southern 
boundary of Nevada. East of the Sierra Nevada the northern 
boundary is arbitrary, as the Mohave Desert merges into the desert 
regions northward and eastward with no definite line of demar- 
cation. 
The area comprised within these boundaries is approximately 
113,250 square kilometers, a little over one fourth that of the 
entire State. ‘The greatest width from east to west is 520 kilo- 
