Page:Popular Science Monthly Volume 57.djvu/81

Rh land view: Mount Hamilton, the site of the Lick Observatory of the University of California; Mount Diablo, the base and meridian of the United States land surveys of central California; and Mount St. Helena, a volcanic peak the summit of which is common to Napa, Sonoma, and Lake Counties, and whose spurs are noted for their quicksilver mines, mineral and hot springs.

The plant life of the immediate Tamalpais region is abundant and interesting; the flowering plants are represented by about eighty orders, three hundred and fifty genera, and from seven to eight hundred species, of which about one hundred are trees and shrubs. Some of the Sierra forms occur on Mount Tamalpais, and it is also the locus of the most southerly extension of certain boreal species. Owing to the wide range of temperature, moisture conditions, and exposures, many of these plants can be found in bloom during every week in the year. During the warm, moist



autumn and winter the hardiest species bloom from October to April in protected areas, and in the cold, exposed areas these same species require the heat of the season from April to September to bring them into bloom. Thus, within a radius of four or five miles from the summit there is not a week in the year when the flowers of certain species can not be gathered—this in face of the fact that