o8 RE. Clements 



members of both groups in accordance with the cUmax in which 

 they find their chief part. As to origin, by far the greater num- 

 ber are of southern derivation, amounting to 75 per cent. The 

 exceptions are chiefly dominants of the mountain chaparral that 

 are common to the Petran and Sierran associations, such as Rhus 

 trilobata, Cercocarptis parvifolius and ledifolius, Amelanchier 

 alnifolia, Holodiscus discolor, and Jamesia americana. A few 

 such as Artemisia tridentata, Atriplex canescens, Chrysotham- 

 ntis nauseosus and viscidiflorus, Eurotia lanata, Gutierrezia saro- 

 thrae, Sarcobatus vei-miculatus, and Ribes cereum range as far 

 north as Canada. 



Desert scrub climax 

 Larrea tridentata Prosopis juHflora 



EnceHa farinosa Acacia greggi 



Acamptopappus sphaerocephalus Baccharis emoryi 

 Haplopappus HnearifoHus Baccharis glutinosa 



Dalea californica Hymenoclea salsola 



Prunus fasciculata Hymenoclea monogyra 



Nolina parryi Pluchea sericea 



Sagebrush climax 

 Artemisia tridentata Sarcobatus vermiculatus 



Atriplex confertifolia Brickellia californica 



Atriplex canescens Viguiera deltoidea 



Chrysothamnus nauseosus Zauschneria californica 



Chrysothamnus viscidiflorus Pentstemon antirhinoides 



Grayia spinosa Eriodictyum californicum 



Eurotia lanata angustifolium 



Salvia carnosa 



Chaparral climax 

 Rhus trilobata Holodiscus discolor 



Cercocarpus parvifolius Jamesia americana 



Cercocarpus ledifolius Arctostaphylus pungens 



Ceanothus cuneatus greggi Arctostaphylus pringlei 



Amelanchier alnifolia Purshia glandulosa 



