175 



49. — Canofia holocantha, Torrey. 



An anoiiial.ous slirab, or small tree^ 10 to 20 feet higli, and entirely 

 without leaves. It occurs on the dry plateaus of Arizona, and i)roba- 

 l)ly in New Mexico. The wood is lieavy and liard, but of little use except 

 for fuel. 



Description. — Tlio branches are straight, spine-like, and peculiar for their smooth 

 green bark with black scars. The seeds are borne in a solitary, erect, woody pod (I 

 inch long) with thin, sharp point, at maturity splitting open at the top, thus forming 

 10 bristle-pointed teeth; seed small, flat, dark, with a thin wing attached to one end. 



50. — Mountain Mahogany. {CercoGarpus ledi/oUus, Xuttall.) 



A low tree or shrub, rarely more than 35 feet in height and 2 feet in 

 diameter ; usually much smaller — 10 to 20 feet. It generally grows on 

 dry rocky slopes between 0,000 and 8,000 feet elevation, and is found 

 in the mountain ranges of northern Idaho, western Montana and Wy- 

 oming, Arizona, and New Mexico (it occurs also on the Pacific coast 

 from Washington Territory to southern California). The wood is dark, 

 exceedingly heavy and hard, but not strong. It furnishes the most 

 valuable fuel of the Rocky Mountain region, and is extensively em- 

 l^loyed in making charcoal. 



l)escrq)iiou.- -IjeaveH i to li inches long, narrow lance-shaped, sharp-pointed ; mar- 

 gins entire, and commonly rolled back; thick, leathery, slightly resinous; smooth 

 above, downy on the under surface ; evergreen. Seed with a hairy tail 2 to 3 inches 

 long. Usually a low and much-branched tree; crown dense. 



51. — Mountain Mahogany. (Gercocarpus iiarvifolins. Nut tall.) 



Chiefly a shrub, but sometimes attaining a height of 20 to 30 feet, 

 with a diameter of 6 to 12 inches. It generally occurs on dry gravelly 

 sod at elevations between 0,000 and 8,000 feet, ranging through the 

 liocky Mountains of Wyoming, Colorado, and New Mexico, w^here it is 

 said to reach its largest size (southern Arizona and southward ; also 

 on coast of California and southward). Like the preceding species, it 

 affords excellent fuel, and where large enough is used considerably for 

 this purpose. 



Description.— 'LesbX as ^ to I| (commonly ^ to f inch) long, on short stems; mostly 

 wedge-shaped at the base, rather coarsely toothed at the upper end, which is rounded 

 or sharp-pointed; young leaves with silky hairs above, with age 1-ess prominent or 

 wanting; whitish on the under surface, with fine, dense wool; evergreen. Seed 

 with a hairy tail 2 to 2 J inches long, sometimes 3 J to 4 inches. 



52. — Western Mountain Ash. {Pyrus sambuoifolia, Cham, and 



Schlecht.) 



Chiefly a shrub 0 to JO feet high, or occasionally a small tree 20 to 25 

 feet, with a trunk sometimes 8 or 10 inches in diameter ; usually con- 

 fined to deep swamps and the banks of streams. In the Rocky Mount- 

 ain region it extends from New Mexico to Colorado (westward to Cali- 

 fornia, noreh to British Columbia and northward; eastward along the 



