76 



I. M. JOHNSTON 



A large number of plants which are confined to the Transition 

 Zone seem to range throughout the zone irrespective of subzones. 

 Among these are, — 



Plants ranging throughout the Transition Zone 

 Pellaa Wrightiana californica Ribes nevadensis 



Phoradendron paucifolium 



Eriogonum nudum 



Eriogonum molcstum Davidsonii 



Dudleya pumila 



Silene verecunda platyota 



Prunus demissa 

 Ceanothus cordulatus 

 Pyrola pallida 

 Gilia latiflora exilis 

 Helenium Bigelovii 



The great majority of plants usually extends up into the Cana- 

 dian Zone or down into the Upper Sonoran Zone. The more 

 conspicuous examples of these are given in the following lists. 



Plants common to the Transition and Upper Sonoran Zones 



Pteris aquilina lanuginosa 

 Cheilanthes Fendleri 

 Cystopteris fragilis 

 Pseudofcuga macrocarpa 

 Bromus grandis 

 Car ex alma 

 Populus trichocarpa 



Qucrcus chrysolepis 



Eriogonum fasciculatum polifolium 



Aquilegia truncata 



Clematis ligusticifolia 



Viola purpurea pinetorum 



Brickellia californica 



Solidago californica 



Plants common to the Transition and Canadian Zones 



Sitanion minus 

 Carex brevipes 

 Allium Breweri 

 Allium Burlewii 

 Salix flavescens 

 Castanopsis sempervirens 

 Eriogonum saxatile 

 Silene Parishii 

 Arabis platysperma 



Ribes cereum 

 Seriocotheca concolor 

 Drudeophytum vestitum 

 Arctostaphylos patula 

 Gilia pungens tenuiloba 

 Monardella cinerea 

 Boschniakia strobilacea 

 Hieracium horridum 

 Symphoricarpus Parishii 



The composition of the Transition flora is somewhat different 

 on the two sides of the mountain. The most conspicuous differ- 

 ence is the absolute lack of Ceanothus cordulatus, Artemisia tri- 

 dentata and Tetradymia canescens on the south or coastal side. 

 On the desert side these three are the most common shrubs. 

 There are a number of plants which, while present on the south 

 side, are very much less frequent there than they are on the 



