4. R. venenàta, DC. (POISON S. or DOGWOOD.) Smooth, or nearly so; _leaflets 7--13, obovate-oblong_, entire.--Swamps. June.--Shrub 6--18° high. The most poisonous species; also called _Poison Elder_. 5. R. Toxicodéndron, L. (POISON IVY. POISON OAK.) Climbing by rootlets over rocks, etc., or ascending trees, or sometimes low and erect; _leaflets 3, rhombic-ovate_, mostly pointed, and rather downy beneath, variously notched, sinuate, or cut-lobed,--high-climbing plants (R. radìcans, _L._) having usually more entire leaves.--Thickets, low grounds, etc. June. [*][*][*] _Flowers polygamo-diœcious, in small solitary or clustered spikes or heads which develop in spring before the leaves; leaves 3-foliolate; fruit as in first group. (Not poisonous)._--(§ LOBADIUM, Torr. & Gray.) 6. R. Canadénsis, Marsh. Leaves soft-pubescent when young, becoming glabrate; leaflets rhombic-obovate or ovate, unequally cut-toothed, 1--3´ long, the terminal one cuneate at base and sometimes 3-cleft; flowers pale yellow. (R. aromatica, _Ait._)--Dry rocky banks, W. Vt. to Minn., and southward.--A straggling bush, 3--7° high; the crushed leaves not unpleasantly scented. Var. trilobàta, Gray. With smaller leaflets (½--1´ long), crenately few-lobed or incised toward the summit.--Long Pine, Neb., and common westward. Unpleasantly scented. § 2. CÒTINUS. _Ovary becoming very gibbous in fruit, with the remains of the styles lateral; flowers in loose ample panicles, the pedicels elongating and becoming plumose; leaves simple, entire._ 7. R. cotinoìdes, Nutt. Glabrous or nearly so; leaves thin, oval, 3--6´ long; flowers and fruit as in the cultivated _Smoke-tree_ (R. Cotinus).--Mo. to Tenn., and southward.--A tree, 25--40° high. ORDER 31. POLYGALÀCEÆ. (MILKWORT FAMILY.) _Plants with irregular hypogynous flowers, 4--8 diadelphous or monadelphous stamens, their 1-celled anthers opening at the top by a pore or chink, the fruit a 2-celled and 2-seeded pod._ 1. POLÝGALA, Tourn. MILKWORT.