2 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 
demonstrating their range northward. Mrs. Blanche Trask, of Santa 
Catalina Island, sent valuable insular lichens. Miss Alice Eastwood, 
as Curator of the Herbarium of the California Academy of Sciences 
at San Francisco, lent a large heretofore undetermined collection of 
Pacific coast lichens, made by Dr. KE. L. Greene, T. S. Brandegee, 
Dr. Albert Kellogg, and others, representing plants from the extreme 
of Lower California to Alaska. This important collection was lost 
shortly after its return to San Francisco in the catastrophe of April 
18, 1906. Mr. F. M. Reed, of Redlands, has also contributed valu- 
able forms. To Dr. J. N. Rose, Associate Curator of the United 
States National Herbarium, the writer is especially desirous of ex- 
pressing his great appreciation of the valued advice and help afforded 
in the preparation of this paper. 
Briefly stated, Southern California, as here understood, is the por- 
tion south of the 36° parallel, containing the counties of Kern, Santa 
Barbara, Ventura, Los Angeles, Orange, Riverside, Imperial, and 
San Diego, in area amounting approximately to one-third that of the 
State. It may be divided into three main topographical sections, a 
coastal, a mountain, and a desert. The first ascends gradually from 
the coast line to the foothills of the second or mountain district, 
reaching an average altitude of 100 meters; it is mostly open country, 
sparsely wooded, fairly well watered, and mainly devoted to agricul- 
ture or grazing. Earth, rock, and corticular lichens are about equally 
represented in it. The second (mountain) section, facing southwest- 
ward, rises abruptly from the former to an average height of 1,500 
meters, with several elevations up to 3,000 and 3,700 meters, and 
having a width of 150 kilometers, more or less; its flanks are clothed 
by an often impenetrable chapparal growth, while toward the sum- 
mits a more open arboreal growth prevails. This district offers a 
rich vegetation of fruticulose and crustaceous as well as foliose lichens 
on earth, rock, and bark. From this toward the third or desert sec- 
tion the descent is more gradual and passes into the desert plateau 
of 1,200 meters elevation, gently sloping east and northeasterly, 
southward descending to, and in some localities even below, the sea 
level. This desert section is arid, practically waterless the greater 
part of the year, sustaining a brushy, with here and there a stunted 
arboreal vegetation. The lichens are chiefly terrestrial or saxicolous, 
bark forms being quite rarely seen. That the scanty precipitation 
and low atmospheric humidity are not entirely accountable for this 
paucity of lichen growth is evidenced by the fact that, though in 
localities sheltered from wind and sunlight, lichens flourish in a meas- 
ure, they do not appear in as great variety of species as elsewhere. 
The prevailing, often severe, dust and sand storms form an active 
factor in prohibiting the life of lichens or their symbionts. In the 
coastal section the average annual precipitation is 30 to 45 cm., less 
