salicacejE. (willow family.) 419 



3. P. heteropliylla, I>. (Downt-leaved Poplar.) Branches round; 

 Uaves heart-shaped or roundish-ovate, obtuse, serrate, white'Vxatly when young, at 

 length nearly smooth, except on the elevated veins beneath. — Sivamps, W. 

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

 ally quite blunt leaves ; the sinus, when heart>shaped, closed 'by the overlapping 

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



4. P, mouilifera, Ait. (Cotton-wood. Nbcklace Poflae.) 

 Young branches sliglitlt/ angled, becoming round; leaves broad/i/ deltoid, with spread- 

 ing prominent nerves, slightly heart-shaped or truncate at the base, taper-pointed, ser- 

 rate with cartilaginous and incurved slightly hairy teeth ; fertile catkins very 

 long; scaies lacaulefringed, not hairy; stigmas neai-ly sessile, toothed, dilated 

 and very large. — Margins of lakes and streams, New England to Illinois and 

 southward, especially westward. — A large tree, 80° high or upwards; the vig- 

 orous branches decidedly angled, bearing largo leaves ; the more stunted being 

 round, with smaller foliage. (P. Canad6nsis, Michx. /. P. laevigata, Willd.) 



5. P* ang'ulata, Ait. ( Angled Cotton-wood.) Branches acutely 

 angular or winged ; leaves broadly deltoid or heart-mate, smooth, crenate-serrate, or 

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

 and southward. — Tree large as the last, and like it bearing very large and 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. balsaillifera, L. (Balsam PofLab. Tacamahag.) Brandies 

 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 a fragrant resinous matter. 



Var. Giindicans. (Balm of GilkaD.) 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 Wisconsin and 

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



P. NIGRA, L., was admitted by the elder Michaux into his Flora, without any 

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

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

 River, above Albany." Lastly, it was described as P. betuli/Slia by Pursh, who 

 further added as its station, " about Lake Ontario." The tree was probably an 

 introduced form of the Emxjpean P. nigra, and was latterly so considered by 

 the younger Michaux himself. A few of these trees are still found in the neigh- 

 borhood of Hoboken, New Jersey. 



P. dilatXta, Ait., the well-known pyramidal Lombaedy Poplar, has 

 been extensively introduced as an ornamental tree, and is found in the vicinity 

 of all old settlements. 



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

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

 than is desirable. 



