338 University of California Publications in Zoology. \yo^- 7 



Plants Ordinarily Occurring in Transition and Found in the Pine 

 Forest Mountains 



(Cool, shaded situations in meadows or along streams, except as noted, 



from 7500 to 8600 feet altitude) 



Prunus demissa (found on favor- Amelanchier alnifolia (found on 



ably exposed slopes at 8000 favorably exposed slopes at 



feet) 8000 feet) 



Aquilegia truncata Arnica chamissonis 



Eibes eereum (ordinarily occurring Aconitum columbianum 



elsewhere in upper Transition Sisymbrium canescens 



and above) Hypericum formosum 



Achillaea millefolium lanulosa Artemisia tridentata (found from 



Aphyllon fasciculatum 4100 to 9400 feet altitude) 



Pentstemon confertus caeruleo-pur- Ceanothus velutinus (on favorable 



pureus slopes) 



Cercocarpus ledifolius (on dry, ex- Veratrum calif ornicum (ordinarily 



posed ridges 7000 to 8800 feet) - occurring elsewhere in upper 



Iris missouriensis (in meadows and Transition and above) 



on dry, open hillsides) 



Plants Ordinarily Occurring in Canadian or Hudsonian and Found in 

 the Pine Forest Mountains 



(8000 feet and above) 



Aquilegia truncata Pinus flexilis 



Eibes eereum Allium validum 



Arnica chamissonis Ceanothus velutinus 



Iris missouriensis (from 7000 feet Veratrum calif ornicum (in mead- 



up) ows 7000 feet in altitude and 



Aconitum columbianum above) 

 S'symbrium canescens 



DISCUSSION OP LIFE ZONES 



The life zones represented in the region are Upper Sonoran 

 and Transition, with a touch of Boreal (see map, pi. 7). 



The desert proper, comprising in this region the broad flats 

 of the Quinn Kiver Valley and the neighboring deserts, is Upper 

 Sonoran. On favorable slopes tongues of this zone invade the 

 mountains to an altitude of 8000 feet at least, as is indicated by 

 the presence at that elevation of Beithrodontomys megalotis 

 deserti and Peromyscus crinitus. 



The zone of widest extent in the mountains is the Transition. 

 The most conspicuous element of its flora on exposed flats and 

 treeless ridges was Artemisia tridentata. The most abundant 



