The Origin of the Desert Climax and Climate 103 



Staphylea trifolia is found from Quebec to Kansas, while bo- 

 landeri is restricted to central and northern California; Styrax 

 californica is more southern, and the limits of pulverulenta are 

 from Virginia to Texas. Both forms of Amorpha occur over 

 the wide area from New Mexico to California, jruticosa reach- 

 ing southern Pennsylvania and californica the San Francisco 

 Bay region. 



The remaining phylads are western, Philadelphus letfisi oc- 

 curing from southern California to British Columbia, and 

 tnicrophylla from Arizona to Colorado. Zauschneria californica 

 ranges from California to Nevada, and arizonica from Califor- 

 nia through Arizona to southwestern Colorado. Eriodictyum 

 californicum extends from southern Oregon through central 

 California, crassi folium southward to the border, trichocalyx 

 along the Cross Ranges to the Santa Rosa Mountains at the west 

 side of the desert, and californicum angusti folium from the east 

 side through southern Nevada and Arizona to New Mexico. 

 Ephedra californica of the southern part of the state meets tri- 

 furca in the Mohave and Colorado deserts, and trifurca stretches 

 east to Texas and Colorado, sharing the area east of the desert 

 with torreyana.T\it more restricted Crossosoma bigelovi occurs 

 from central Arizona across the desert to Lower California, 

 while californica is confined to islands off the southern coast. 



Species of the Desert and Eastward or Westward 



FORBS 



The number of species found both in the desert and eastward 

 into the desert plains or mixed prairie is 89; of these, 49 are an- 

 nuals, 39 of which extend as far east as New Mexico, Colorado, 

 or Texas. Almost all the perennials likewise stretch far to the 



