504 



TREES OF NORTH AMERICA 



green and smooth on the upper surface, pale yellow-green on the lower surface, 

 about 2' long and |' wide, with slender yellow midribs and 3 or 4 pairs of thin 

 obscure primary veins; their petioles slender, slightly winged at the apex, at first 

 villose, becoming glabrous and rose-colored below the middle, about ^' long; on 

 vigorous shoots often rhond>oidal, coarsely serrate, often slightly incisely lobed, 

 coriaceous, 3' long and 2' wide, with stout broadly winged petioles. Flowers i' in 

 diameter, on long slender pedicels, in rather compact globose many-flowered com- 

 pound corymbs; calyx-tube broadly obconic, glabrous, the lobes linear, entire or 

 glandular, witli minute caducous glands, glabrous on the outer, sparingly villose on 

 the inner surface, often tinged with red; stamens 20; anthers pale yellow. Fruit 

 ripening in September, on long pedicels, in drooping few-fruited clusters, short- 

 oblong, full and rounded at the ends, dark crimson and marked by many large 

 white dots when fully grown, becoming black and lustrous at maturity, Y-^' long; 

 calyx slightly enlarged, persistent, with elongated closely appressed entire lobes 



slightly villose and dark red on the upper side below the middle; flesh thin, yellow, 

 dry and mealy; nutlets 3-5, \' long, narrowed and rounded at the ends, slightly 

 ridged on the back, the ventral cavities broad and shallow. 



A tree, occasionally 20 high, with a slender stem covered with dark brown scaly 

 bark, erect branches forming a narrow rather open head, and slender bright red- 

 brown lustrous branchlets marked by numerous pale lenticels, and unarmed, or 

 armed with straight slender spines usually about 1' long. 



Distribution. Banks of mountain streams, often forming thickets; Wyoming to 

 southwestern Colorado and western Utah; most abundant on the Wasatch Mountains 

 of Utah. 



8. CERCOCARPUS, H. B. K. Mountain Mahogany. 



Trees or shrubs, with scaly bark, rigid terete branches, short lateral spur-like 

 branchlets conspicuously roughened for many years by the crowded narrow horizontal 

 scars of fallen leaves, minute buds, the scales of the inner rows accrescent on the 

 growing shoots and often colored. Leaves alternate, simple, entire, or serrate, coria- 

 ceous, straight-veined, short-petiolate, persistent; stipules minute, adnate to the base 

 of the petiole, deciduous. Flowers axillary on the short lateral branchlets, sessile 

 or short-pedicellate, solitary or fascicled; calyx-tube long and cylindrical, abruptly 



