05C Order 123.— SAURURACEjE. 



long and of equal or greater width), dark green, petioles 2 to 3' long and laterally 

 oompressed, so that they can scarcely remain at rest in any position, and are 

 thrown into excessive agitation by the slightest breeze. The trembling of the 

 "aspen leaf" is proverbial. Amenta plumed with silken hairs, about 2' long, 

 pendulous. Apr. 



4 P. grandidentata Mx. Large Poplar. Lvs. roundish-ovate, acule, with 

 large, unequal, sinuate teeth, smooth, villous when young ; bracts fan-shaped, 5-cleft 

 and silky-fringed. — Woods and groves, Can. and Nor. U. S. not uncommon. 

 St. 40f high, with a diam. of If, straight, covered with a smooth, greenish bark. 

 Branches distant, coarse and crooked, clothed with leaves only at their ex- 

 tremities, with terete twigs. Lvs. 3 to 5' long and nearly as wide, clothed 

 with thick white down in spring, but becoming perfectly smooth. Amcnts 3 to 

 4' long, all the parts hairy, the sterilo longer than the fertile. Stam. about 12, 

 as in the preceding species. May. 



5 P. heteroph^lla L. Cotton Tree. Branches terete; lvs. roundish-ovate, 

 obtuse, uncinately serrate, cordate at base, the small auriculate lobes over-closed, 

 white-tomentous when young, at length nearly smooth ; ovaries with a long pedicel 

 and conspicuous style. — Swamps, N. Eng. (rare) to 111. and La. A tree 40 to 60f 

 high, trunk 1 to 2f diam. Lvs. 3 to 6' long, with small teoth r blunt or nover 

 acuminato at apex, and the base Jobc3 often so overlapping as to conceal tho 

 insertion of tho petiole. Apr., May. 



5 P. balsamifera L. Balsam Poplar. Tacameiiac. Branches terete ; lvs. ovate, 

 acuminato, with close-pressed sorraturos, white and reticulate-veiny beneath. 

 glabrous both sides; bracts of tho ament dilated, laciniate-l'ringed, slightly hairy; 

 stam. 40 to 50. — Swamps and river banks, Me. to Penn., N. Y., Can. and tho N. 

 W. coast. A largo tree, 40 to 80f high, trunk 1 to 2f diam. Lvs. 2 to 4' long. 

 Sterilo aments 2 to 3' long, fertile at length 4 to 6'. Stam. purple. Buds in spring 

 covered with an aromatic resin which may bo separated in boiling water. 



7 P. candicans Ait. Balm of Gilead. (Fig. 268, 269). Branches terete, lvs. 

 ovate, cordate, acuminate, closely and unequally serrate, whitish and reticulate- 

 veined benoath, petiolo hirsute ; bract3 of tho ament oval, Iaciniate-fringed ; stam. 

 about 20. — A fino tree of strong and peculiar fragrance, often cultivated, rarely 

 growing wild, Can. and the Northern U. S. Height 30 to 50fj with a pyramidal 

 head of dense aniple foliage. Lvs. 4 to G' long, at length smooth and dark green 

 above. Sterilo ament3 2 to 3' long, fertile 4 to G. Buds filled throughout with 

 fragrant rosin. 



8 P. nigra L. p. betulifolia Torr. Black Poplar. Young branches pubes- 

 cent; lvs. deltoid-rhombic, conspicuously acuminate, finely crenate-serrate, smooth 

 both sides; aments without hairs. — Trees 30 to 40f high, planted at Iloboken, 

 N. J. and perhaps in Penn. \ Eur. (P. betulifolia Ph. P. Hudsoniea Mx.) 



9 P. dilatata Ait. Lombardy Poplar. Lvs. smooth, acuminate, deltoid, 

 serrate, the breadth equaling or exceeding the length ; trunk lobed and sulcate. — 

 Early brought to this country, and has been planted about many a dwelling and 

 in villago streets. It3 rapid growth is tho only commendable quality it possesses, 

 while tho huge worms by which it is often infested render it a nuisance. 

 | Italy. 



10 P. alba L. Abele. Silver-leaf Poplar. Lvs. cordate, broad-ovate, 

 lobed and toothed, acuminate, dark green and smooth above, very white-downy 

 beneath ; fertile aments ovate ; stig. 4. — A highly ornamental, cultivated tree. 

 Nothing can bo moro striking than tho contrast between the upper and lower 

 surfaco of the leaves, f Eur. 



Order CXXIII. SAURURACEiE. Saururads. 



Herbs with jointod stems, alternate, entire loaves furnished with stipules. Flow- 

 ers iu spikes, perfect, naked, having neither corolla nor calyx. Stamens definite. 

 Ovarii 3 to 5, moro or less united. Seeds ascending. Embryo enclosed in a sac 

 (amnios), outsido of hard, mealy albumen. Fig. 264. 



