242 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



ing to exposure. Within this area, too, are found a larger number of 

 species than in any of the other zones. The trees of the east slope are 

 the alpine fir, Douglas fir, spruces, limber pme, lodgepole pine, cotton- 

 wood, and aspen; but of these, the limber pine and cottonwood do 

 not occur in sufficient abundance to be an important element of the 

 forest. On the west slope are found the same trees, but in addition the 

 great silver fir, hemlock, western white pine, larch, giant cedar, and 

 canoe birch. The chief shrubs of the Canadian Zone are the following : 

 Ground juniper, yew (west slope only) , numerous species of willows, 

 alders, purple clematis, Oregon grape, gooseberry, currants, ninebark 

 (west slope), white meadowsweet, red raspberry, black raspberry 

 (west slope), thimbleberry, mountain-spray, several species of wild 

 rose, chokecherry, pin cherry, mountain-ash, black hawthorn (often 

 a tree on the west slope), servicebeny, buckthorn, maple (often a 

 small tree), mountain lover, deerbrush, Canada buffaloberry, devil's- 

 club (west slope), red-osier dogwood, Labrador tea (west slope), 

 menziesia, whortleberries, elderberry, twinberries, snowberry, and 

 highbush cranberry (west slope). The following is a list of some 

 of the more characteristic herbaceous plants of the zone. Those 

 marked with an asterisk extend also into other zones in more or less 

 abundance. 



Xerophyllum te^ax* Aralia nudicauUs. 



Veratrum viride. . Heracleum lanatum* 



Clintonia uniflom. Sanicula marilandica. 



Disporum spp. Angelica lyallii. 



Streptopm amplexifolius* Cornus stolonifera. 



Claytonia parvifolia. Pyrola a^arifolia* 



Arenariaformosa* Chimaphila umhellata occidentalis. 



Actaea rubra. Galium triflorum. 



Thalictrum megacarpuvi* Galium trifidum. 



Nymphaea polysepala. Linnaea borealis. 



Cardamine breweri. Hieracium albifiorum. 



Tiarella xinifoliata* Prenanthes sagittata. 



Fragaria spp. Aster conspicuus. 



Lupinus sericeus* Aster sayianus. 



Lupinus tenellus* Aster engelmannii* 



Geranium viscossisimum. Balsamorrhiza sagittata. 



Sphaeralcea rivularis. Anaphalis margaritacea. 



Viola canadensis. Adenocaulon bicolor. 



Viola orbiculata. Arnica latifolia. 



Epilobium angusti/olium. Senecio triangularis.* 



Epilobium adenocaulon. 



The timbered portions of the Canadian Zone are easily recognized 

 by the characteristic tree species, with the accompanying herbaceous 

 plants; but the open slopes are not so easily classified, since there 

 is often a puzzling admixture of Transition and Hudsonian species. 

 As remarked above, Canadian plants extend far down along the 

 streams. In this connection one fact should be noted: Running 



