N. ORD.-AN ACARDIACE&. 38 
Sect.—TOXICODENDRON, TOURN. 
GENUS.—RHUS, 
SEX, SYST._PENTANDRIA TRIGYNIA. 
RHUS TOXICODENDRON. 
POISON IVY. 
SYN.—RHUS TOXICODENDRON, LINN.; R. TOXICODENDRON, VAR. QUER- 
CIFOLIUM, MICHX.; R, VERRUCOSA, SCHEELE; R. TOXICARIUM, AND 
HUMILE, SALISB.; R. RADICANS, VAR. TOXICODENDRON, PERS. ; 
TOXICODENDRON PUBESCENS, MILL. 
COM. NAMES.—POISON IVY, THREE-LEAVED IVY, POISON OAK, POISON 
VINE, MERCURY; (FR.) SUMAC VENENEUX, ARBRE A POISON ; (GER.) 
GIFTSUMACH. : 
A TINCTURE OF THE FRESH LEAVES OF RHUS TOXICODENDRON, LINN. 
Description.—This decumbent or more or less erect shrub, grows to a height 
of from 2 to 4 feet, or more, according to whether Rhus radicans is distinct from 
this species or not. Roof reddish, branching. Leaves 3-foliate, thin; /ea/lets rhom- 
bic-ovate, acute, rather downy beneath; they are entire when young (see plate), 
but when full grown become variously dentate, crenate, sinuate, or cut-lobed. 
The lateral leaflets are unequal at the base, and sessile, the terminal one larger 
and situated at the end of a prolongation of the common petiole. /nflorescence 
loose, slender, axillary, racemose panicles. /Vowers polygamous. /7uit glabrous, 
globose, pale brown ; zzé/e¢ somewhat gibbous, striate, and tuberculate. 
History and Habitat.—The Poison Ivy grows in thickets and low grounds, 
quite common in North America, flowering in June, 
Rhus toxicodendron was introduced into England as a plant in 1640; but was 
not used as a medicine until 1798, when Du Fresnoy, a physician at Valenciennes, 
had brought to his notice a young man who had been cured of an herpetic erup- 
tion (dartre) on his wrist, of six years’ standing, on being accidentally poisoned 
by this plant. He thereupon commenced the use of this plant in the treatment of 
obstinate herpetic eruptions, and in palsy; many cases of each yielding nicely to 
the drug.* Since Du Fresnoy’s success, the plant has rapidly gained a place in 
general practice, meeting some success in the treatment of paralysis, rheumatism, 
amaurosis, and various forms of chronic and obstinate eruptive diseases. 
The milky juice of this species is used as an indelible ink for marking linen, 
and as an ingredient of liquid dressings or varnishes for finishing boots and shoes, © 
* Des caractéres, du traitement, et de la cure des datres, etc., par Pusage du Rhus radicans. 
