Dicotyledones. 73 



WHITE-MARGINED SPURGE. Erect annuals with stout stems from i to 3 feet high. 

 Bracts of the involucre white-margined and petallike. The uppermost leaves op- 

 posite or whorled and with conspicuous white, petallike margins. In dry soil. 



ANACARDIACEJE. SUMAC FAMILY. 



Shrubs or small trees, with acrid, resinous, or milky secretions, 

 mostly alternate leaves, and perfect or polygamo-direcious flowers. 

 Calyx 3-7-cleft, most frequently 5 -cleft, and petals when present of the 

 same number. Stamens usually as many or twice as many as the 

 petals. Ovary i-celled and i-ovuled. Styles 1-3. Fruit generally a 

 small drupe. Sometimes poisonous. 



I. RHUS. Sumac. 



(The old Greek and Latin name.) 



Shrubs or trees, with alternate, odd-pinnate, 3-foliate, or simple 

 leaves. Flowers mostly polygamous in axillary or terminal panicles. 

 Calyx 5-parted, and petals 5. Stamens 5, inserted between the lobes 

 of a flattened disk at the base of the calyx. Fruit generally a small, 

 dry drupe. 



1. Rhus. trilobata, Nutt. (Gr., tri, three ; lobos, lobe.) ILL-SCENTED SUMAC 

 or SKUNK BUSH. Shrub 2 to 6 feet high, mostly glabrous. Leaves 3-foliate, the 

 leaflets sessile or nearly so, 5 to i inch long, few lobed or incised toward the 

 summit. Flowers yellow green, in clustered spikes, appearing before the leaves. 

 Unpleasantly scented. Rocky hillsides. 



2. Rhus aromatica, Ait. (Gr., aromatikos, pertaining to spice.) (R. Canaden- 

 sts, Marsh.) FRAGRANT or SWEET-SCENTED SUMAC. Similar to the preceding 

 species, but the leaflets 2 to 4 inches long and pleasantly aromatic, and crenate or 

 dentate above the middle. Rocky hillsides. 



3. Rhus radicans, L. (L., radicans, having roots.) (R. Toxicodendron in 

 Gray's " Manual.") POISON IVY or POISON OAK. Woody; climbing trees, etc., 

 by means of adventitious rootlets. Sometimes shrubby and not climbing. Leaves 

 3-foliate, leaflets i to 4 inches long, the terminal longer stalked than the lateral 

 leaflets. Flowers green in loose, axillary panicles. In thickets and low grounds. 



4. Rhus hirta, Sudw. (L., hirtus, hairy.) STAG-HORN SUMAC. Large shrub 

 or small tree. Leaves pinnate, with 11-31 leaflets. Leaves and twigs with a 

 velvety pubescence. In dry and rocky soil. 



5. Rhus glabra, L. (L.,glaber, bald.) SMOOTH or SCARLET SUMAC. Shrub 

 or small tree. Leaflets 11-31. Foliage and twigs glabrous and somewhat glaucous. 

 In dry soil. 



