556 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



western Arizona, southeastern California (?), northwestern Sonora, 

 and Baja California. 



Represented in Arizona by var. pubescens Johnston. A large shrub 

 or small tree, reaching a height of 4.5, occasionally 6 m. (15 to 20 feet), 

 and a trunk diameter of 0.6 m. (2 feet). The fruits have exceedingly 

 bitter stones. The ranges of C. globosa and the nearly related C. 

 spathulata apparently do not overlap in Arizona, the former not 

 having been collected east of the Ajo Mountains, and the latter not 

 west of the Baboquivari Mountains. 



2. SAGERETIA 



A straggling shrub with slender, somewhat spiny, divaricate branches; 

 leaves nearly opposite, bright green, shining; flowers in glomerules, 

 these forming open leafy panicles; petals present, whitish; ovary 

 superior; fruit a somewhat fleshy drupe with 3 stones. 



1. Sageretia wrightii S. Wats., Amer. Acad. Arts and Sci. Proc. 20: 



358. 1885. 

 Greenlee County to eastern Maricopa, Cochise, and Pima Counties, 

 3,500 to 5,200 feet, in canyons among rocks, March and September. 

 Western Texas, southern Arizona, and Mexico. 



3. RHAMNUS. 8 * Buckthorn 



Shrubs or small trees, not spiny; leaves opposite; flowers perfect or 

 unisexual, greenish, axillary, in small fascicles or solitary, with or 

 without petals; calyx free from the ovary; fruit a drupe with 2 to 4 

 stones. 



All of the Arizona species are ornamental. The laxative drug 

 cascara is obtained from the bark of R. purshiana, a species of the 

 Pacific Coast States. R. crocea is an alternate host of the crown rust 

 disease of oats. The plants, especially the more or less evergreen 

 forms, are of some value as browse in winter, and the fruits are eaten 

 by wild pigeons and other birds. 



Key to the species 



1. Bud scales present; flowers in fascicles without a common peduncle, commonly 

 4-merous; style exserted, cleft to about the middle; leaves evergreen, the 

 blades with spinose-dentate margins, broadly ovate or suborbicular, not 

 more than 3 cm. long, commonly truncate or emarginate (rarely acute) at 

 apex, glabrate or permanently short-pilose and often bronzed beneath; 



fruits bright red at maturity 1. R. crocea. 



1. Bud scales none; flowers in pedunculate cymes, commonly 5-merous; style not 



exserted, the stigma 2- or 3-lobed; leaves deciduous, the blades with serrulate 



or nearly entire margins; fruits black or nearly so at maturity (2) . 



2. Leaf blades evergreen, thickish, whitish-tomentose beneath, oblong-lanceolate 



to broadly elliptic, commonly less than 3 cm. wide; fruits usually 



2-seeded 2. R. californica. 



2. Leaf blades deciduous, thin, green on both faces, sparsely to copiously 

 pubescent beneath but not tomentose, broadly elliptic to ovate-oblong, 

 commonly more than 3 cm. wide; fruits usually 3-seeded. 



3. R. BETULAEFOLIA. 



S1 Reference: Wolf, C. B. the north American species of rhamntjs. Monog. Rancho Santa Ana 

 Bot. Gard. Bot. Ser. 1: 1-136. 1938. 



