Oak (Quercus engelmannii); the buckwheat Oxytheca trilobata; 

 Gematis pauciflora; MatiUja Poppy {Romneya coulteri); the jewel 

 flower Streptanthus campestris; Laurel Sumac {Rhus laurind) 

 and Lemonadeberry {R. integrifolia); Ceanothus megacarpus and 

 Red-heart (C. spinosus)', and the monkey f\ov/QT Mimulus brevipes. 



The Transition Life Zone is well defined, especially on its 

 lower borders. The Sierra Transition lies between average altitudes 

 of 2,000 and 5,000 feet (610 and 1 ,524 m) and has a mean tem- 

 perature of 55° to 60° F (13° to 16°C) and an average rainfall of 

 25 to 35 inches (64 to 89 cm). It includes the main forest belt, 

 and is repeated in the mountains of Southern California and in 

 the Coast Ranges, where the latter rise to sufficiently high alti- 

 tudes. This life zone is distinctive and, on the whole, rather defi- 

 nitely circumscribed. It contains, for California, a greater number 

 of species of trees and shrubs than any other life zone and has, 

 in addition, a very large population of herbs. 



Widely developed in some parts of the state and very narrow 

 in others, the Arid Transition of the Great Basin underlies the 

 lower margin of the main Humid and Sierra Transition. It is, in 

 California, a drier and more exposed sub-area, often with a pre- 

 ponderance of brush slopes and scattered trees. Its most charac- 

 teristic species are Ponderosa Pine {Pinus ponderosa), Basin Sage- 

 brush (Artemisia tridentata), the msLnz^iniiSi Arctostaphylos 

 patula, Garrya fremontii and the plum Pninus subcordata. 



The Sierra Transition is developed and forms a broad band. 

 It carries the less open part of the forest belt. The dominant 

 forest species are Ponderosa Pine {Pinus ponderosa) and Sugar 

 Pine {P. lambertiana); Incense Cedar {Calocedrus decurrens) and 

 White Fir {Abies concolor). The Big Tree {Sequoiadendron gigan- 

 teum) is a marked feature of this zone in the southern part of 

 the Sierra Nevada. The dry or more open forest or forestless 

 slopes present many shrubs of wide range such as California 

 Hazelnut {Corylus comuta var. califomica), Thimble Berry 

 {Rubus parviflorus), Service Berry {Amelanchier alnifolia), three 

 species of Ceanothus, Mountain Dogwood {Comus nuttallii), 

 and a few other shrubby species. On the dry flats or open wet 

 meadows or swamps as well as on the forest slopes there are 

 various characteristic herbs. 



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