ANACARDIACEiE. (CASIIEW FAMILY.) 119 



§ 1. RHUS proper. Fruit symmetrical, with the styles terminal. 



* Flowers polygamous, i)i a terminal thyrsoid panicle ; fruit globular, clothed 



with acid crimson hairs ; stone smooth ; leaves odd-pinnate. {Sot poisonous.) 

 — (§ Sumac, DC.) ' _ 



1. R. typhina, L. (Staohorx St^MACn) Branches, and stalla densely 

 velvet y-hair y : leaflets 11 -31, pale beneath, oblons^-lanceolate, pointed, serrate, 

 rarely laeiniate. — Hillsides. 'June. — Shrub or tree 10-30° higlj, jvltli orange- 

 colored wood. Apparently hybridizes with the next. 



2. R. glabra, L. (Smooths.) Smooth, somewhat (jlaitcous ; Xcw^iit^ \\ - 

 31, whitened beneath, lanceolate-oblong, pointed, serrate. — Rocky or barren 

 soil. rFune, July..— Shrub 2-12*^ high. A var. has laeiniate leaflets. 



3. R. COpallina, L. (Dwarf S.) Branches and sialks dnnny -, ptfioUs . 

 wincj-manjined between the 9-21 oblong or ovate-lanceolate, (often entire) leaf- 

 lets, which are obli(jae or unequal at tlie b;i.se, smootli and shining above. — 

 Rocky hills. July. — Shrub 1 - ''^ high, with running roots. 



* * Flowers polygamous, in loose and slender axillary panicles ; fruit globular, 



glabrous, whitish or dun-colored ; the stone striate; leaves odd-pi^nale or 3- 

 foliolate, thin. (Poisonous.) — (§ Toxicodendron, DC.) 



4. R. venenata, 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. O i''^' ^ ^ ' ' 



5. R. Toxicodendron, 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, vafiously 

 notched, sinuate, or cut-lobed, — high-climbing plants (R. radlcans, L.) having 

 usually more entire leaves. — Thickets, low grounds, etc. June. 



* * * Flowers pol ygamo-di<ecious, in small solitary or clustered spikes or heads 



ivhich develop in spring before the leaves ; leaves Sfoliolate ; fruit as injirst 

 group. (Not poisonous). — (§ Louadium, Torr. & Gray.) 



6. R. Canadensis, Marsh. Leaves soft-pubescent when young, becom- 

 ing 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, ^1/7.) — Dry rocky banks, W. Vt. to Minn., and 

 southward. — A straggling bush, 3-7° high; the cruslied leaves not uu])lea3- 

 antly scented. 



Var. trilob^ta, Cray^ With smaller leaflets (i - 1' long), crenately few- 

 lobed or incised toward the summit. — Long Pine, Neb,, and common west- 

 ward. Unpleasantly scented. 



§ 2. C6TINUS. 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. OOtinoideS, Xntt. ' Glabrous or nearly so ; leaves thin, oval, 3 - 6' 

 long; flowers and fruit iw in the cultivated Smoke-tree (R. Cotinus) — Mo. to 

 Tenn., and southward. — A tree, 25-40° high. 



