ROSACES 



579 



Colorado plateau south of the Colorado River; widely and generally distributed at alti- 

 tudes between 5000 and 8000, but nowhere abundant. Passing into var. rufula Sarg., 

 differing in the rusty brown pubescence on the lower side of the midrib of the leaves, in the 

 pubescent petiole and lower part of the rachis, in the puberulous ovary, and in the rusty 

 brown pubescence of the young branchlets. 



Distribution. With the species on many of the mountain ranges of southern New Mex- 

 ico and Arizona at altitudes between 5400 and 6000. 



19. Prunus caroliniana Ait. Wild Orange. Mock Orange. 



Leaves oblong-lanceolate, acuminate, mucronate, with entire thickened slightly re volute 

 margins, or rarely remotely spinulose-serrate, glabrous, coriaceous, dark green and lustrous 

 on the upper surface, paler on the lower surface, 2'-4|' long and i'-l-|' wide, and obscurely 

 veined, with a narrow pale midrib; persistent until their second year; petioles stout, broad, 

 orange-colored; stipules foliaceous, lanceolate, acuminate. Flowers appearing from Feb- 

 ruary to April, on slender pedicels about \' long, from the axils of long-acuminate scarious 

 red-tipped bracts, in dense racemes shorter than leaves; calyx-tube narrow-obconic, the 

 lobes small, thin, rounded, undulate on the margins, reflexed after the flowers open, decidu- 

 ous; petals boat-shaped, minute, cream-colored; stamens exserted, orange-colored, with 

 glabrous filaments and large pale anthers; ovary gradually narrowed into a slender erect 

 style enlarged above into a club-shaped stigma. Fruit ripening in the autumn, remaining 

 on the branches until after the flowering period of the following year, oblong, short-pointed, 

 black and lustrous, \' long, with a thick skin, and thin dry flesh; stone short-ovoid, pointed, 

 nearly cylindric, about \' long, full and rounded at base, with thin fragile walls, obscurely 

 ridged on the ventral suture and deeply grooved on the dorsal suture. 



A tree, 30-40 high, with a straight or inclining trunk sometimes 10' in diameter, slender 

 horizontal branches forming a narrow oblong or sometimes a broad head, and glabrous 

 branchlets marked by occasional pale lenticels, slightly angled, at first light green, becom- 

 ing bright red, and in the second season light brown or gray. Winter-buds acuminate, ' 



Fig. 532 



long, covered with narrow pointed dark chestnut-brown scales rounded on the back. Bark 

 about \' thick, gray, smooth or slightly roughened by longitudinal fissures, and marked by 

 large irregular dark blotches. Wood heavy, hard, strong, close-grained, light red-brown or 

 sometimes rich dark brown, with thick lighter colored sapwood. The partially withered 

 leaves and young branches are often fatal to animals browsing upon them, owing to the 

 considerable quantities of hydrocyanic acid which they contain. 



