154 American MroLAND Naturalist Monograph No. 4 



They are commonly found on moist wooded slopes, along streams, or in 

 chaparral. The bushes are very persistent, sprouting again and again after 

 being cut off from the base. The herbage is not poisonous to livestock and 

 furnishes good browse for deer. Birds and small mammals eat the berries. 

 The flowers furnish honey for bees. The foliage takes on a beautiful red 

 Autumn coloring. 



Field Guide to the Species 



Leaflets mostly blunt-pointed or rounded at the tip; irregularly toothed; occurs on 



Pacific Slope I. T. diver silohum. 



Leaflets mostly sharper-pointed, the teeth usually fewer, occurs in Southwest and 



Rocky Mountains 2. T . radicans. 



1. Pacific Poison Oak (Toxicodendron diver sllobum (T. 6c G.) 

 Greene) . — Erect shrub 3 to 8 feet high, or sometimes a climbing vine with 

 stems up to 30 feet long; leaves divided into 3 leaflets; leaflets roundish to 

 oblong, irregularly and coarsely toothed or lobed, mostly rounded at the tips, 

 2/3 to 3 inches long, shiny dark green above, paler below; flowers small, green- 

 ish, delicate, borne in loose drooping clusters in the axils of the leaves; fruits 

 small, roundish, white with thin dark lines running lengthwise. (Syn. Rhus 

 diversiloba T. & G.). 



Occurrence. — YOSEMITE, 2,200 to 4,500 feet: El Portal; lower Yosemite Valley; 

 Hetch Hetchy; Rancheria Mountain, sequoia, 2,000 to 4,000 feet: trail to Ash 

 Mountain lookout; Clough Cave; Cedar Cave. 



2. Western Poison Ivy (Toxicodendron radicans Kuntze var. Ryd- 

 bergi (Small) Rehd.).- -Usually a low shrub 1 to 3 feet high with dark yel- 

 lowish-green foliage; leaflets 3 (rarely 5), 1 to 4 inches long, egg-shaped with 

 pointed tips, the margins coarsely toothed or lobed, or sometimes not toothed; 

 flowers greenish-yellow, delicate, borne in loose drooping clusters in the leaf- 

 axils; fruits small, roundish, white with fine green veins running lengthwise. 

 (Syns. Rhus radicans L. var. Rydbergi (Small) Rehd., R. toxicodendron L. 

 v'ar. Rydbergi Garrett.) 



Occurrerice. — YELLOWSTONE, rare: Gardiner River north of Mammoth. ROCKY 

 MOUNTAIN, rare. MESA VERDE. ZION. occasional in moist places, about 4,000 to 4,500 

 feet: near south entrance; the Narrows trail at Zion Stadium; Emerald Pools; Weep- 

 ing Rock. 



Sumac (Rhus L.) 



Many of the sumacs are very attractive shrubs. The leaves of smooth 

 sumac and staghorn especially are very attractive in the Fall when they turn 

 a beautiful red color. The foliage of these two sp>ecies is of little value as a 

 browse, but that of skunkbush sumac is eaten to some extent by deer. Some 

 species have considerable tannin in the bark. The berries are eaten by birds 

 and small mammals and the pioneers discovered that because of their acid 

 properties, they could be used to make a cooling drink by soaking them in 

 water and adding sugar. For this reason R. trilobata is sometimes called 

 lemonade sumac. 



The Indians made considerable use of the sumacs wherever they were 



