ANACARDIACE^E. (CASHEW FAMILY.) 119 



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



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



with acid crimson hairs ; stone smooth ; leaves odd-pinnate. (Not poisonous.) 

 -( SUMAC, DC.) 



1. R. typhina, L. (STAGHORN SUMACH) Branches and stalks dense! y 



velvety-hairy : leaflets 11 -31, pale beneath, oblong-lanceolate, pointed, serrate, 

 rarely laciniate. Hillsides. June. Shrub or tree 10-30 high, with orange- 

 colored wood. Apparently hybridizes with the next. 



2. R. glabra, L. (SMOOTHS.) Smooth, somewhat glaucous ; leaflets 11 - 

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

 soil. June, Julv. Shrub 2-12 high. A var. lias laciniate leaflets. 



3. R. copallina, L. (!)WAI;F S.) Branches and stalks downy ; petioles 

 wing-margined between the 9-21 oblong or ovate-lanceolate (often entire) leaf- 

 lets, which are oblique or unequal at the base, smooth and shiniug above. 

 Kocky hills. July. Shrub 1-7 high, with running roots. 



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



glabrous, u-hitish or dun-colored; the stone striate ; leaves odd-pinnate or 3- 

 foliolate,thin. (Poisonous.) ( TOXICODENDROX, DC.) 



4. R. venenata, DC. (POISON S. or DOGWOOD.) Smooth, or nearly 

 so; leaflets 7-13, obovate-oblony, entire. Swamps. June. Shrub 6-18 

 high. The most poisonous species ; also called Poison Elder. 



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, variously 

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

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



* * * Flowers polygamo-dicecious, in small solitary or clustered spikes or heads 



whicli develop in s]>r!ng. before tin Irai-es ; leares 3-folio/ate ; fruit as in first 

 group. (Xot poisonous). ( LOBADIUM, Torr. & Gray.) 



6. R. Canad6nsis, 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, Ait.) Dry rocky banks, W. Vt. to Minn., and 

 southward. A straggling bush, 3-7 high; the crushed leaves not unpleas- 

 antly scented. 



Var. trilobata, Gray. With smaller leaflets (- 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. 



1. R. COtinoides, Nutt. Glabrous or nearly so ; leaves thin, oval, 3 - 6' 

 long; flowers and fruit as in the cultivated Smoke-tree (R. Cotiuus) Mo. to 

 Term., and southward. A tree, 25-40 high. 



