548 MISC. PUBLICATION 4 2 3, XT. S. DEPT. OF AGRICULTURE 



67. ANACARDIACEAE. Cashew family 



1. RHUS.™ Sumac 



Shrubs, the sap usually acrid and resinous, sometimes poisonous; 

 leaves alternate, either simple and entire, or 3-foliolate, or pinnate; 

 flowers regular, perfect or unisexual, mostly 5-merous, small, green- 

 ish, yellowish, or whitish, in axillary or terminal panicles, with a ring- 

 shaped or cup-shaped disk around the ovary; fruit a small 1 -seeded 

 drupe. 



All of the Arizona species are ornamental. The fruits, except in 

 poison-ivy (R. radicans), are thin-fleshed, sweet, pleasantly acid, and 

 can be used to make a refreshing beverage. They are an important 

 food of birds and other wild animals. From the latex of an Asiatic 

 species, R. verniciflua, the fine lacquer of China and Japan is 

 manufactured. 



Key to the species 



1. Fruits yellowish white when mature, shiny, glabrous or nearly so, never 

 glandular-pubescent; plant finely pubescent or glabrate; stems erect, 

 ascending, or climbing by aerial rootlets; leaves deciduous, 3-foliolate, the 

 midlobe long-stalked; leaflets up to 10 cm. long, oblong-lanceolate to 

 ovate, usually coarsely few-toothed; inflorescences loose, paniculate, 



appearing after the leaves; petals greenish white 1. R. radicans. 



1. Fruits red when mature, glandular-pubescent (2). 



2. Leaves simple, evergreen, leathery, entire or very nearly so (3). 



3. Blades of the leaves broadly ovate, acute or short-acuminate, often 

 conduplicate, bright green above; petioles usually more than 1 cm. 

 long 2. R. ovata. 



3. Blades broadly oblong or oval, obtuse or acutish, flat, dark green above 



with conspicuous whitish veins; petioles usually less than 1 cm. long. 



3. R. KEARNEYI. 



2. Leaves compound, sometimes reduced to a single leaflet in R. trilobata (4). 



4. Leaflets not more than 3, coarsely crenate, the midlobe sessile or nearly so, 



often cleft; leaves deciduous, not leathery; inflorescences dense, spike- 

 like, appearing before the leaves (except in one form) ; petals yellow. 



4. R. TRILOBATA. 



4. Leaflets more than 3 or, if only 3, then the leaves evergreen and leathery 



(5). 



5. Flowers very numerous, in naked terminal inflorescences; stems below 



the inflorescence, and the leaves, glabrous or glabrate; leaves 



deciduous, the leaflets seldom fewer than 11, whitish beneath, 



oblong-lanceolate, conspicuously serrate, 4 to 10 cm. long. 



5. R. GLABRA. 

 5. Flowers not very numerous, often in axillary as well as terminal inflores- 

 cences; leaflets 9 or fewer, paler but not whitish beneath, entire (6) . 

 6. Leaves evergreen, the rachis not winged; leaflets 3 to 5, coriaceous, 

 somewhat shiny above, glabrate, petiolulate, 2 to 6 cm. long, 1 to 

 3 cm. wide, acute or short-acuminate at apex; flowers appearing 



after the leaves 6. R. choriophylla. 



6. Leaves deciduous, the rachis winged; leaflets 5 to 9, not coriaceous 

 or shiny, pilose, sessile, less than 2 cm. long, 2 to 6 mm. wide, 

 rounded to acutish at apex; flowers appearing before the leaves. 



7. R. MICROPHYLLA. 



1. Rhus radicans L., Sp. PL 266. 1753. 



Toxicodendron radicans Kuntze, Rev. Gen. PL 1: 153. 1891. 



Apache County to Coconino County, south to Cochise, Santa Cruz, 

 and Pima Counties, 3,000 to 8,000 feet, common in rich soil of ravines 

 and canyons, April to September. Throughout most of North America. 



80 Reference: Barkley, F. A. a monographic study of rhus and its immediate allies in north 

 and central America. Mo. Bot. Gard. Ann. 24: 265-498. 1937. 



