"WILLOW FAMILY. 401 



the N. States, and also in N. Eu. and Asia ; leaves thick and firm, erect, 

 ■whitened beneath, ovate-lanceolate or oval, tapering towards the top and 

 sometimes at the base, finely and obtusely toothed; young branches 

 nearly cylindrical. Also cult, in many forms, the marked types being : 

 var. viminalis, Loudon, of moderate stature, sharply angled twigs and 

 broad-lanceolate willow-like twigs ; and var. lati folia, Loudon (P. Nolestii 

 of nurserymen), with large ovate or cordate-ovate rather blunt leaves. 



Var. candicans, Gray. Balm op Gilead. A strong-growing, spreading 

 tree, frequently planted, and esteemed for its vigor and hardiness and the 

 resinous fragrance of its large buds in springtime. Leaves are broad, 

 heart-shaped, green above and veiny and rusty-white beneath, the leaf -stalk 

 usually hairy and somewhat flattened. L. Ontario, Mich., etc. Rare wild. 



-i- *- Petioles prominently flattened, so that the leaves dangle in the wind. 



P. laurifdlia, Ledeb. (P. Certinensis.) Large tree, planted from 

 Siberia ; leaves broad-ovate in outline, with a rounded or tapering base 

 and rather short point at the apex ; the margin rather closely toothed, 

 wavy; leaf -stalk comparatively short, only moderately flattened, gland- 

 less at the top ; stipules present and conspicuous ; shoots slightly hairy. 



P. monilifera, Ait. Cottonwood, Carolina Poplar. Leaves trian- 

 gular-ovate in outline, with a straight or truncate base and a long point 

 at the ^apex ; margin coarsely scallop-toothed, plane ; leaf-stalk long, 

 much flattened beneath the blade of the leaf, and commonly bearing two 

 or three gland-like bodies at its top ; stipules absent or minute (falling 

 early) ; shoots glabrous. Large tree ; common. 



P. nigra, Linn. Black Poplar, of Eu. A medium-sized tree, very 

 sparingly planted, with broadly triangular or diamond-ovate, small leaves, 

 which are not deeply toothed, and commonly hairy young shoots. It is 

 familiar in this country in the 



Var. Itdlica, Du Hoi. (P. dilatata, P. fastigiXta.) Lombardt Pop- 

 lar. A tree of very tall strict growth; glabrous young shoots, and more 

 tapering base to the leaves. Probably Asian. 



* * White Poplars or Aspens, with short, non-glutinous, often pubescent 



buds. 



*- Petioles terete. 



P. heterophylla, Linn. Downy Poplar. 40°-80° high ; leaves round- 

 ovate or heart-shaped, with the sinus closed by the overlapping lobes, 

 obtuse, serrate with incurved teeth, 3'-5' long, white wool deciduous only 

 with age, leaving traces on the veins beneath and on the petioles ; fruit- 

 ing catkins smooth. Swamps, Conn, to 111., and S. 



•i- •>- Petioles strongly flattened (except in some forms of the first'). 



** Leaves cottony, at least beneath, even when old. 



P. 6lba, Linn. Abele or White P. Tree planted from Eu., with 

 spreading branches, roundish, slightly heart-shaped, wavy -toothed or 

 lobed leaves soon green above, very white-cottony beneath ; spreads in- 

 veterately by the root. Many varieties, of which the most marked is var. 

 Bolleana, with deeply lobed white-bottomed leaves, and a fastigiate habit. 



*+ ++ Leaves cottony when unfolding, but soon smooth and green on both 

 sides ; bark smooth and close, greenish-white. 



P. tremuloldes, Michx. American A. Small tree, common in woods 

 N.; small roundish-heart-shaped leaves with small regular teeth; scales 

 of catkins cut into 3 or 4 linear lobes, fringed with long hairs. 



P. grandidentata, Michx. Larger Am. A. Middle-sized tree, common 

 in woods ; larger roundish-ovate leaves with coarse irregular blunt teeth ; 

 scales unequally 5-6-cleft, slightly fringed. Weeping forms in cultivation. 

 GRAY'S P. F. Sc g. bot. — 26 



