Class XXII. Order XII. 369 



acuminate, pubescent underneath, nine nerved, the 

 lateral nerves simple. 



Syn. DIOSCOREA PAXICULATA. MX. 



A delicate, slender-twining vine. Stem twisted and winding 

 from right to left. Petioles reflexed, contorted, channelled. 

 Leaves heart shaped, acuminate, entire, beautifully marked with 

 long, distinct, single nerves, glabrous above, smooth or villous 

 beneath. Flowers minute, alternate, sessile, on long, filiform, 

 axillary peduncles. Calyx in the barren flowers in six ovate 

 segments, with six minute anthers. Fruit inversely heart-shaped, 

 three winged. Woods on the Concord turnpike, rare. May, 

 June. Perennial. 



POLYANDRM. 



430. POPULUS. 



POPULUS TREMULOIDES. Mich. American Aspen. 



Leaves roundish, abruptly acuminate, serrulate, pu- 

 bescent at the edge. Mich.f. 



The small, tremulous leaves of this Poplar have great affinity 

 to those of the European Aspen, whose quivering foliage has 

 long been proverbial. The tree somewhat exceeds the middle 

 size. The flowers appear in April, long before the leaves, in 

 pendulous, silken aments ; the calyx of the barren flowers of a 

 dark, chesnut colour with a fringe of white hairs. Corolla 

 white. Anthers numerous, deep brown with white pollen. The 

 leaves are small, compared with other species, light, roundish, 

 scarcely hearted at base. The bark is smooth, and the wood 

 light, fine, soft, and perishable. 



POPULUS GRANDIDENTATA. Mick. LttTgC Aspen OT Poplar. 



Petioles compressed ; leaves round-oval, smooth both 

 sides, unequally sinuate, with large teeth, the younger 

 ones villous. Mich.f. 



Syn. POPULUS TREPIDA. Muhl. 



This tree is occasionally met with in our woods, but is much 

 less common than the preceding species. It is easily distinguish- 

 ed from the various cultivated poplars by the large, unequal in- 

 47 



