178 American Midland Naturalist Monograph No. 2 



4. Twigs and leaves glabrous; along roads and fences, and in open 



woods, common throughout 111. June-July. Smooth Sumac 



R. glabra L. 



4. Twigs and petioles villous-hirsute; woods, n. III., extending southw. 

 to La Salle, Cass, Morgan, and Hancock counties, occasionally 

 introd. elsewhere June-July. {^R. hirta (L.) Sudw.} Staghorn 

 Sumac R. typhina L. 



3. Leaflets entire or nearly so; fruit glabrous, whitish or pale greenish, in 

 axillary panicles; plants poisonous to the touch; tamarack bogs and 

 swampy ground. Lake and Kankakee counties. June-July. Poison 

 Sumac R. vernix L. 



L Leaves with 3 leaflets. 



5. Flowers in loose axillary panicles, appearing after the leaves; fruit gla- 

 brous, greenish white; plants erect, trailing, or climbing, poisonous to 

 the touch; along fences and in woods, or on sand dunes, common. May- 

 July. [/?. toxicodendron of auth., not L.] Poison Ivy R. radicans L. 



5. Flowers in short dense panicled spikes, catkin-like before opening, appear- 

 ing before or with the leaves; fruit red, pubescent; foliage not poison- 

 ous, fragrant when bruised. 

 6. Flowers nearly sessile, appearing before the leaves; leaflets 2-6 cm. long, 

 rhombic-obovate to ovate, acute; petioles villosulous to nearly gla- 

 brous; gravelly or rocky banks locally throughout 111., except the n. 

 counties; more frequent southw. May. \R. canadensis Marsh.; R. 

 crenata of Rydb., not Thunb.; Schmaltzia jormosa Greene; S. illino- 



ensis Greene] Fragrant Sumac R. aromatica Ait. 



6. Flowers on pedicels 2-3 mm. long, on leafy twigs; leaflets 1-2.5 cm. 

 obtusish, crenately few-lobed or -toothed above the middle; petioles 

 puberulent or tomentulose; sandy banks and dunes; known from 

 Cook, Jo Daviess, Mason, and Hancock counties; also n. Ind. May. 



[^Schmaltzia arenarta Greene, Leaflets 1:130. 1905] 



R. arenaria (Greene) n. comb. 



99. Staphyleaceae DC. — Bladdernut Family 

 1. Staphylea L. 



S. trifolia L. American Bladdernut. Moist woods and thickets, common. 

 Apr.-May. 



100. Aceraceae Lindi. — Maple Family 



1. Acer L. — Maple 



1. Leaves simple, palmately lobed; floral disk present; anthers ellipsoid, not 

 apiculate. 

 2. Leaves silvery whitish on the lower surface; flowers i" dense sessile clus- 

 ters, appearing before the leaves. 



3. Leaves 5-lobed, the lobes serrate or cleft or parted; petals none; ovary 

 tomentose; samaras divergent, pubescent; chiefly in alluvial soil, com- 

 mon. Mar. -Apr. Silver Maple A. saccharinum L. 



