SALICACF^E. (WILLOW FAMILY.) 467 



with white silky wool, at length smooth both sides ; scales cut into 5-6 unequal 

 email divisions, slightly fringed. — Woods: common, especially northward. — 

 A rather larger tree than the last, with a smoothish gray bark. 



3. P. heterophylla, L. (Downy Poplar.) Branches round; leaves 

 heart-shaped or roundish-ovate, obtuse, serrate, white-woolly when young, at length 

 nearly smooth, except on the elevated veins beneath. — Swamps, W. New 

 England to Illinois .and southward. — Tree 40° -60° high, with large, usually 

 blunt leaves ; the sinus, when heart-shaped, closed by the overlapping lobes 

 which conceal the insertion of the nearly round leaf-stalk. 



4. P. monilifera, Ait. (Cotton-wood. Necklace Poplar.) Young 

 brunches slightly angled, becoming round; leaves broadly deltoid, vjith spreading promi- 

 nent nerves, slightly heart-shaped or truncate at the base, taper-pointed, serrate with 

 cartilaginous and incurved slightly hairy teeth ; fertile catkins very long ; scales 

 lacerute-fringed, not hairy ; stigmas nearly sessile, toothed, dilated and very large. 

 — Margins of lakes and streams, W. New England to Illinois and southward, 

 especially westward. — A large tree, 80° high or upwards ; the vigorous branched 

 decidedly angled, bearing large leaves ; the more stunted round, with smaller 

 foliage. (P. Canadensis, Michx.f. P. lasvigata, Willd.) 



5. P. angulata, Ait. (Angled Cotton-wood.) Branches acutely angu- 

 lar or winged ; leaves broadly deltoid or heart-ovate, smooth, crenate-serrate, or with 

 obtuse cartilaginous teeth. — Low grounds, Pennsylvania to Wisconsin and 

 southward. — Tree large as (and probably a mere variety of) the last, and lik 

 it bearing very large heart-shaped leaves (7' -8' in length and breadth) on 

 young plants and suckers : on full-grown trees only one fourth of that size, and 

 commonly without the sinus. 



6. P. balsamifera, L. (Balsam Poplar. Tacamahac.) Branches 

 round ; leaves ovate, gradually tapering and pointed, finely serrate, smooth on both 

 sides, whitish and reticulately veined beneath ; scales dilated, slightly hairy ; sta- 

 mens very numerous. — N. New England to Wisconsin, and northward. — A 

 tall tree, growing on the borders of rivers and swamps : its large buds varnished 

 with copious fragrant resinous matter. 



Var. candicans. (Balm of Gilead.) Leaves broader and more or less 

 heart-shaped, pointed, serrate, whitish and reticulate-veined beneath ; petiole 

 commonly hairy. (P. candicans, Ait.) — N. New England to Lake Superior 

 and Kentucky: rare in a wild state, but common in cultivation. 



P. nigra, L., was admitted by the elder Michaux into his Elora, without any 

 mention of its locality. It was afterwards published by his son, under the name 

 of P. Hudsonica : he, however, found it " only on the banks of the Hudson River, 

 above Albany." Lastly, it was described as P. betulifblia by Pursh, who further 

 added as its station, " about Lake Ontario " It was probably introduced from 

 Europe, and was latterly so considered by the younger Michaux himself. 



P. dilatata, Ait., the well-known Lombardy Poplar (probably a form of 

 P. nigra) has been extensively introduced as an ornamental tree. 



P. Alba, L., the Abele or White Poplar of the Old World, is occasionally 

 planted, when it spreads widely by the root, and becomes more common than is 

 desirable. 



