184 MEDICAL BOTANY. 



iii. 43.) The S. arroeira is said to poison those who sleep beneath it ; but a 

 fragrant oil is obtained by distillation from its leaves, and its bark is employed 

 as a febrifuge in Brazil, according to Buchner [Jour. Chim. Med. vi. 204) ; 

 it contains a large proportion of tannin, and the extract forms a good substi- 

 tute for catechu. 



Rhus. — Linn. 



Sepals 5, united at base, persistent. Petals 5, ovate, spreading-. Stamens 5 (rarely 

 10), equal. Styles three, short, distinct, or united. Stigmas 3. Fruit drupaceous, almost 

 dry. Root bony, 1 -celled. Seed solitary, suspended on a funiculus, arising from the 

 base of the nut. 



This genus is extensive, and the species are found in all parts of the world, 

 but are most numerous in Southern Africa. In North America there are 

 about ten or twelve, belonging to different sections or sub-genera, which might 

 with advantage be considered as genera. They are shrubs or very small 

 trees, with simple or unequally-pinnate leaves. Their medical properties 

 vary much, some of the species being extremely poisonous, whilst others are 

 innocuous, and afford agreeably acid berries. Several species are officinal in 

 the U. S. and other Pharmacopoeias. 



R. toxicodendron, Linn. — Stem erect, decumbent, or climbing. Leaves trifoliate, 

 somewhat pubescent. Leaflets angularly incised, or entire, the lateral ones inequilateral. 

 Flowers in axillary, sub-sessile racemes. Fruit sub-globose, smooth. 



Linn., Sp. PL 381 ; Torrey and Gray, Fl. i. 218 • Stokes, ii. 160 ; Ste- 

 phenson and Churchill, iii. 167 ; Bigelow, Med. Bot. iii. 17. 



Common Names. — Poison Oak ; Poison Ivy ; Poison Vine, &c. 



Foreign Names. — Sumac venemeux, Herbe a la puce, Fr. ; Geft-Su- 

 mach, Gr. ; Albero del veleno, It. 



Description. — The root sends up many stems, which are either erect, decumbent, or 

 when they meet support, ascend a wall, fence, or tree, in the. same manner as ivy, by ra- 

 dicles thrown out at intervals. The bark is a brownish-gray colour. The leaves vary 

 much, in the erect varieties being usually entire, or variously and irregularly sinuate- 

 toothed or lobed, whilst in the climbing kinds they are almost entire or nearly so; in all 

 cases they are smooth on the upper surface, but more or less pubescent beneath. The 

 lateral leaflets are always inequilateral, nearly sessile, and smaller than the middle ones. 

 The flowers are in simple, axillary raceme^, on very short peduncles, of a whitish-green 

 colour. The calyx is small, permanent, and divided into five segments. The petals are 

 also five, ovate, acuminate, and spreading. The stamens are shorter than the corolla, and 

 support small roundish anthers. The ovary is superior, roundish, and is crowned by. a 

 short style, bearing three small, cordate stigmas. The fruit is a globular, smooth, dry 

 berry, containing a single bony seed. 



Many botanists have considered the varieties of this plant as distinct spe- 

 cies, under the names of toxicodendron and radicatis, but it is now well 

 ascertained that they are not entitled to this rank. Dr. Bigelow observes, 

 " Among the plants which grow abundantly round Boston, I have frequently 

 observed individual shoots from the same stock having the characters of both 

 varieties. I have also observed that young plants of ii. radicans frequently 

 do not put out rooting fibres, until they are several years old ; and that they 

 seem in this respect to be considerably influenced by the contiguity of sup- 

 porting objects." This agrees with my own observations of the plant, and is 

 the opinion of our best authority on such subjects, Drs. Torrey and Gray, as 

 well as that of Michaux and Pursh. 



The Poison Oak was early noticed, and was described in 1635 by Cornu- 



