a6 F. E. Clements 



Grass transads no longer found in the desert 



Stipa comata Elymus triticoides 



Stipa minor Koeleria cristata 



Stipa eminens Epicampes rigens 

 Stipa coronata ' Bromus marginatus 



Bouteloua hirsuta Andropogon scoparius cirratus 



Bouteloua rothrocki Aristida d-schiedeana 



Bouteloua radicosa Eragrostis secundiflorus 



Aristida p-fendleriana Panicum huachucae 



Several o£ the grasses named above are dominants of the true 

 prairie, notably Andropogon scoparius, Bouteloua racemosa, 

 and Koeleria cristata. The last-named retains this role through 

 the mixed prairie and into the bunchgrass association of Cali- 

 fornia. In reduced rank, though still as a dominant, B. racemosa 

 appears in both mixed prairie and desert plains; Andropogon 

 becomes postclimax in both. Bouteloua rothroc\i, B. radicosa in 

 several forms, and Aristida d-schiedeana are dominants of the 

 desert plains, while Elymus triticoides is the valley consociation 

 throughout the California prairie. 



FoRB Transads 



Of this group, the perennial species are of chief importance as 

 being more characteristic of climax areas, while the annuals 

 are in large part and often wholly serai. Like the grasses, this 

 group is divisible into those still persisting in the desert and 

 those that have disappeared from it but that survive today on 

 both sides. The latter are generally more mesic than the former, 

 and a number of them, namely. Erysimum asperum, Glycyrhiza 

 lepidota, Lotus americanus, Verbena hastata, and Urtica gracilis, 

 extend east into the true prairie or farther. There are approxi- 

 mately 70 desert transads, of which 41 are annuals. The transads 



