nized
the agricultural, and indeed the whole, economy of California. At the
two ends of Cajon Pass, only four or five kilometres apart, are the two
utterly distinct floras of the Mohave desert and the San Bernardino
valley. Despite the presence of the pass, plants do not spread, so great
is the difference of climatic conditions. On the desert the same plant
will vary in different years from 4 in. to 10 ft. in height when equally
mature, according to the rainfall and other conditions of growth. Many
mature plants are not taller than 0.4 to 0.8 in. The tree yucca often
attains a height of 20 to 25 ft., and a diameter of 1.5 ft. About 600
species of plants were catalogued in desert California in 1891 by a
government botanical party. The flora of the coast islands of California
is very interesting. On Santa Cruz Professor Joseph Le Conte found 248
species, nearly all of which are distinctively Californian, 48 being
peculiar to the surrounding islands and 28 peculiar to Southern
California. Various other things indicate a separation of the islands
from the mainland in quaternary times; since which, owing to the later
southward movement on the continent of northern forms in glacial times,
there has been a struggle for existence on the mainland from which the
islands have largely escaped.

_Forests._--The forests and agricultural crops of the state demand
particular notice. In 1900 the woodland was estimated by the United
States census at 22% of the state's area, and the total stand at 200,000
million ft. of timber. The variety of forest trees is not great, but
some of the California trees are unique, and the forests of the state
are, with those of Oregon and Washington, perhaps the most magnificent
of the world. At least the coniferous forests which make up nine-tenths
of California's woodland surpass all others known in number of species
and in the size and beauty of the trees. Forty-six species occur,
namely, 32 species of pitch trees (18 pines), 12 species of the
cypresses and their allies (2 sequoia), and 2 species of yews or their
allies. Peculiar to California are the two species of sequoia
(q.v.),--the redwood (_S. sempervirens_), and the big-tree (_S.
gigantea_), remnants of an earlier age when they were common in other
parts of the world. The redwood grows only in a narrow strip on the
Coast Range from Southern Oregon (where there are not more than 1000
acres) down nearly to the Golden Gate, in a habitat of heavy rai