288 THE NORTH AMERICAN GRASSLAND 



Clilorogalum. The other perennials belong to the genera typical of 

 mixed and true prairie for the most part, though with uniformly dif- 

 ferent species and earlier times of blooming. The most characteristic 

 of the perennials is naturally Eschscholtzia, but Ranunculus, Del- 

 phinium, Lupinus, Sidalcea, Pentstemon, Viola, Artemisia, Hclianthus, 

 and Solidago are of the first rank also. Even more typical are the 

 great masses of annuals, representing more than 50 genera and several 

 hundred species. These fluctuate widely with the amount and dis- 

 tribution of the rains and the proper conjunction with rising tempera- 

 tures. Under favorable conditions in the upper San Joaquin, where 

 the competition of the grasses has been all but eliminated by overgraz- 

 ing, the number and size of such annual communities are bej'ond be- 

 lief. In the spring of 1935 with supranormal rainfall, the carpet of 

 brilliant blues, oranges, and yellows covered an area approximately 

 50 miles wide and 100 miles long. 



Proclimaxes. The outstanding community of this group is the dis- 

 climax composed of weedy annuals, chiefly grasses, introduced from 

 Europe during Spanish days. As a consequence of excessive grazing 

 pressure during the dry season from May to December, this covers 

 nine-tenths or more of the non-cultivated portion of the original 

 bunch-grass climax. The major dominant is wild oats, Avena fatua, 

 usually forming a dense tall consocies that simulates natural grassland. 

 It may alternate or mix in varying degree with several species of 

 Bromus, Hordeum, and Festuca, as these do with each other or with 

 one or more of the three common Erodiums (Fig. 69). 



The shrinkage of the woodland climax under climatic desiccation 

 has produced an oak savanna along the margins of valleys and over 

 foothill slopes generally, and in this digger pine {Pinus sabijiiana) is 

 often an important element. A similar process has operated upon the 

 coastal sagebrush of Artemisia, Salvia, Eriogonum, and their asso- 

 ciates, as well as upon the lower consociation of chaparral composed 

 chiefly of Adenostoma. The interesting Joshua tree {Yucca brcvi- 

 folia) of the margins of the Mohave Desert likewise forms savanna 

 with Stipa pulchra, S. speciosa, Elymus, and Poa in the semi-desert 

 arm known as Antelope Valley, a phenomenon entirely in harmony 

 with the behavior of other species of Yucca elsewhere in the grassland 

 climax. As to semi-permanent subclimaxes, there are two of wide 

 extent. One of these is the great complex of "tule" marshes in the 

 deltalike region where the Sacramento and San Joaquin rivers meet 

 in central California, and the other an extensive belt of stable coastal 

 dunes found largely in the general region of Pismo and IMonterey 

 Bays. 



