PREFACE 



The Flora of Western Middle California includes a descriptive account of 

 the native and naturalized plants growing in the region about San Francisco 

 Bay, east to the Sacramento and San Joaquin rivers, north to the south line 

 of the counties of Mendocino, Lake and Colusa, and south to the Pajaro River 

 and Pacheco Pass. While the geographical limits are marked almost through- 

 out by the natural features of rivers, mountain ranges and valleys, the area 

 as a whole is not an especially natural one. Rather, this area (the choice of 

 which was governed both by the needs of its human population and by it^ 

 accessibility) comprises portions of several distinct areas, namely, the North 

 Coast Ranges, the South Coast Ranges and the Great Valley of California. 



The most distinctive and sharply defined feature of the region of this Flora 

 is the Redwood belt. The Redwood (Sequoia sempi rvirens) grows in a narrow 

 strip along the coast, mainly on the western face of the outer (or seaward) 

 Coast Range. Wherever the main range breaks down to low sandy or clay 

 hills, below 500 to 1800 feet in altitude, the Redwood does not grow, and there 

 are in consequence transverse gaps in the continuity of the Redwood belt. Such 

 gaps occur in central and northern Marin county, on the San Francisco penin- 

 sula, and in the Pajaro and Salinas valleys between the Santa Cruz and Santa 

 Lucia mountains. Associated with the Redwood arc the Tan Oak, Madrona and 

 Douglas Fir, and growing on the forest floor we find such distinctive Redwood 

 plants as Oxalis oregaaa, Scliopus bigelovii, Clintonia andrewsiana, VancouveHa 

 parviflora, Viola sarmentosa, Vaccinium ovatum and Gaultheria shallon. 



In climate and in plant population the Redwood belt presents as a whole 

 slight diversity. Its climate is very uniform, showing comparatively slight 

 differences in temperature throughout the year, with a rainy season succeeded 

 by a season of fogs. Outside the Redwood belt is a beach strip characterized 

 by such shore species as Abronia latifolia ami umbellata, Lathyrus littoralis, 

 Lupinus littoralis. Attiplex californica, Mesembryanthemum aeqmlaterale, Ar- 

 temisia pycnoeepJiala, Franseria bipinnatifida and chamissonis. 



The climate of the Coast Ranges inside the Redwood belt and of the Great 

 Valley is markedly different from that of the immediate coast or Redwood 

 region. These areas have also but two seasons, a rainy season lasting from 

 mber to April and a dry season from May to October, when rain is 

 normally absent. March and April may, however, be spoken of as spring 

 months since the annual vegetation is then at its height, and September and 

 October as fall months since then is the period of greatest development of the 

 fall flora. 



The Coast Ranges of our region are characterized by barren slopes or hills, 

 by slopes openly wooded with oaks, or by chaparral, the latter being the most 

 marked featured The term chaparral refers to the extensive and dense colonies 

 of shrubs which clothe mountain slopes and ridges and includes such typical 



