6io 



Poison Sumacs 



these poisonous qualities. The leaves of these plants are unequally pinnate or 

 3-foliolate, the leaflets either entire-margined, or variously toothed or lobed. The 

 small green flowers are in axillary or lateral clusters, usually panicles; they are 

 cither dioecious or polygamous; the 4 to 6 sepals are persistent at the base of the 

 fruit; there are 4 to 6 petals and usually as many stamens, those of the pistillate 

 flowers small and usually abortive; the ovary in the pistillate flowers is one-celled, 

 enclosing i pendulous ovule. The fruit is a drupe, with a thin smooth outer 

 coat, which early separates and falls away from the inner, which is waxy and 

 encloses a ribbed stone. The type species is Toxicodendron vulgare Miller, one 

 of the Poison Vines of eastern North America. 



Only one of the several North xA.merican species forms a tree. 



POISON SUMAC Toxicodendron Vernix (Linnaeus) Shafer 



Rhus Vernix Linna.'us. Rhus venenata de Candolle 



This small tree inhabits swamps and occurs from southern Ontario and Ver- 

 mont to eastern Massachusetts and Florida, westward to Minnesota, Arkansas, 

 and Louisiana. It is also known as Poison elder. Poison ash, Poison oak, Swamp 



dogwood, and Poison dogwood, and is 

 dangerously poisonous to the touch. It 

 sometimes attains a height of 8 meters, 

 with a trunk 1.5 dm. in diameter, but is 

 usually smaller, and often a mere shrub. 

 Some people are said to be affected by 

 coming close to the plant without act- 

 ually touching it. 



The smooth bark is thin and hght 

 The young twigs are smooth. 



gray. 



brown or orange-brown. The buds are 

 pointed, purpHsh, the terminal ones 2 

 cm. long or less, their scales finely hair}\ 

 The leaves are smooth, except when 

 quite young, when they are quite hairy; 

 when fully grown they are 1.5 to 4 dm. 

 long, their stalks round and slender, the 

 6 to 12 lateral leaflets stalkless or ver}' 

 short-stalked, ovate or rhombic, thin, 

 2.5 to 15 cm. long, pointed, green on 

 both sides and entire-margined ; the terminal leaflet is long-stalked. The axillaiy 

 panicles of flowers are 7 to 20 cm. long, the staminate ones on one tree, the pistil- 

 late on another; the numerous insignificant flowers are about 2 mm. broad, open- 

 ing in June or July; the usually 5 pointed lobes of the calyx arc much shorter 

 than the narrow petals, whose tips are sHghtly reflexed. The large panicles of 



Fig. 561. Poison Sumac. 



