44 DIALYPETALOUS EXOGENS 



GLABROUS RHUS. Common Sumach. Smooth Sumach. 



Juice, copiously milky. Stem 3 to 8 or 10 feet high, irregularly branched; 

 branches stout, with a large pith. Leaflets 2 to 3 or 4 inches long, 10 to 15 pairs, 

 with a terminal one, becoming crimson in autumn. Flowers yellowish-green, in 

 dense ovoid terminal panicles. Fruit densely villous, finally bright purple, and 

 sharply acid. 

 Hob. Old fields; fence-rows, &c.: common. Fl. June. Fr. Sept. 



4. R. veneiiata, DC. Leaflets obovate-oblong, abruptly acu- 

 minate, the margin very entire and slightly revolute. 

 POISONOUS RHUS. Poison Sumach. Swamp Sumach. 



Juice resinous, Stem 8 to 12 or 15 feet high, branching above. Leaflets 2 to 3 

 inches long, 4 to 6 pairs, with a terminal one. Flowers greenish, in subterminal 

 and axillary panicles. Fruit smooth and shining, pale yellowish-green, larger 

 than in any of the preceding. 

 Hob. Swampy rivulets : not very common. Fl. June. Fr. Sept. 



Obs. This species is very poisonous to many persons. It was 

 formerly (but erroneously) supposed to be identical with the varnish 

 tree, of Japan. 



f f Leaves trifoliolate. 



5. R. ToxiCOdendron, L. Stem erect, or climbing by radi- 

 cles; leaflets obliquely ovate or rhomboid, acuminate, entire or 

 angularly dentate. 



R. radicans. L. $ FL Cestr*. ed. 2. 

 POISON-TREE RHUS. Poison- Vine. Poison-Ivy. 



Juice resinous. Stem, in the erect variety, 2 to 5 or 6 feet high, with leaflets larger 

 and variously toothed or lobed ; in the climbing variety, stem 8 or 10 to 30 or 40 feet 

 long, branching, adhering to trees, fences, and other objects, by means of numer- 

 ous radicating processes; the leaflets 3 to 5 or 6 inches long, more commonly entire ; 

 common pttioles 3 to 6 inches in length. Flowers yellowish-green, in slender race- 

 mose axillary panicles. Fruit dry, smooth and shining, pale brown. 

 Hob. Woods, fence-rows, &c.: frequent. Fl. May. Fr. Sept. 



Obs. The climbing variety (formerly regarded as a distinct species, 

 and named R. radicans,] is much the most common, here: but some 

 fine specimens of the erect variety were collected in the South 

 Western part of the County, in 1841, by Mr. JOHN M'MiNN. They 

 are both poisonous, to some persons. 



ORDER XXVIII. ACERA^CEAE. 



Trees, yielding a sweet sap; leaves opposite, without stipules; flowers polygamo- 

 dioicous, regular but often apetalous or unsymmetrical ; fruit a pair of more or 

 less diverging separable 1-seeded samaras, winged at summit, with the outer margin 

 'thicker and obtuse; seeds nearly without albumen. 



?6. ACER, L. 



[The ancient classical name of the maple.] 



Sepals 5, connected at base. Petals 5, or often none. Stamens 5 to 

 .8. Styles 2, united ; ovary on a glandular-lobed disk. 

 - f Flowers in pendulous racemes, or corymbs, appearing with the leaves. * Petals 5. 



1. A. PSETJDO-PLATANUS, L. Leaves cordate at base, 5-lobed, une- 

 qually dentate; flowers in terminal pendulous racemes; fruit 

 diverging. 



