size in the past two centuries, since it occupied lands that have 

 been transformed into agricultural land. As a result, Valley Grass- 

 land occupies only a small remnant of its former area. 



Originally, Valley Grassland was made up of various perennial 

 bunch grasses (Plate 9D) such as needle grass (Stipa spp.), bunch 

 or blue grass (Poa spp.), and three-awn (Aristida spp.). These 

 grasses have completely disappeared in large areas of the Central 

 Valley where the native grass cover has been removed and the 

 land has been planted with cultivated crops, or where destructive 

 sheep or cattle are pastured. Much of the Central Valley is still 

 grassland, but even in grazed areas the cattle or sheep have exter- 

 minated the native perennial grasses, and these have been replaced 

 by introduced annual grasses such as brome grass (Bromus spp.), 

 wild oats (Avena spp.), and fescue (Festuca spp.). The golden 

 hills that characterize much of California are golden in the sum- 

 mertime because of the dry stems and leaves of these introduced 

 annual grasses; it is probable that when these areas were occupied 

 by the native perennial grasses they were green or gray -green 

 during most of the year. 



Valley Grassland occurs most extensively in the Central Valley, 

 but also is present in some of the low valleys or gentle slopes of 

 the Coast Ranges and in some areas of the Transverse and Penin- 

 sular Ranges. It also occurs along the coast from San Luis Obispo 

 County southward to the Mexican border. Rainfall in the Valley 

 Grassland is variable, but is generally less than 20 inches (51 cm) 

 per year. This low rainfall probably is responsible for the absence 

 of trees in the Valley Grassland. Summer temperatures may be 

 very high, and heavy frosts are common in some areas in the 

 winter. 



In the spring, portions of the Valley Grassland are covered by 

 a rich array of spectacularly colorful spring annuals (Plate lOA). 

 Areas that are well known to professional and amateur botanists 

 include the low hills and valley bottoms in the Bakersfield area 

 and the Tehachapi foothills, the Solano delta area, the Red Bluff 

 region, and some of the interior valleys of the Coast Ranges. In 

 years in which there is abundant rainfall, hundreds or thousands 

 of acres of Valley Grassland are occupied by masses of these 

 showy annuals. 



98 



