SALICACEAE 411 
Petioles laterally flattened. III. DELTOIDES. 
Petioles terete or channeled. IV. HETEROPHYLLAE. 
I. GRANDIDENTATA 
Leaf-blades finely crenate-serrate: bud-scales eer or 
merely ciliate. 1. P. tremuloides. 
Leaf-blades coarsely sinuate-dentate: bud-scales tomentulose. 2. P. grandidentata. 
P ALB 
Leaf-blades very broad, several-lobed and "m toothed, the 
pubescence on the lower surface often felt-like. . P. alba. 
III. DELTOIDES 
Stamens 6-8: tree-trunk fastigiately branched. 4. P. italica. 
Stamens 5 or more: tree-trunk widely branched. D. P. balsamifera. 
I HETEROPHYLLAE 
Anthers ellipsoid : pistillate aments loosely ee capsule 
slender-pedicelled : young leaves white-tomentos 6. P. heterophylla. 
Anthers obo e-oval: pistillate aments ea " flowered : 
capsule stout-pedicelled : young leaves not white-tomentose. 7. P. candicans. 
1. P. tremuloides Michx. Tree becoming 15 m. tall (rarely taller), the bark 
ooth or smoothish, greenish-white: 7 m ovate to orbieular-ovate, or 
ng, abruptl 
thickets, various provinces, Tenn. to Calif, 
Alas., Ont., N. S., and Newf. 
. grandidentata Michx. Tree becom- 
"n m. ‘long. 2 
SPEN. ARGE-TOOTHED  ASPEN.)— Woods, | 
stream- d usually in burns and clearings, and various provinees, N. C. 
to Minn., and N. S. 
3. P. alba L. Tree becoming 35 m. tall, the nen T except when old and 
ee dc ur ovate or orbicular in outlin mewhat rhombie, 5—10 
. long, s or somewhat A white- tomentose beneath: ament- bracts 
nate. aie ovoid, 2.5- long.— d POPLAR. SILVER-LEAVED 
P ILVER-POPLAR. Dut ee BEECH. — Cult. uu rounds, roadsides, and 
fields, locally omer our range, and in other parts of the U. S. and S Can. 
Nat 
4. P. italica Moench. Tree with eee ee e trunk, becoming 25 
m. tall: leaf-blades deltoid, subrhomboidal, mewhat r einform, mostly 5-8 
em. long, crenate or crenate-serrate: unns e vnb 2-5 em. long: stamens 
few: capsule ovoid, 6-8 mm. long. [P. dilatata Ait.]— (Lo MBARDY- ee 
shes cae )—Roadsides, fields, meadows, and pastures, locally in ou 
ange. Nat. 
5. P. balsamifera L. Tree with widely branched trunk, becoming 40 m. tall, 
pe oe dark: leaf-blades deltoid to ovate-deltoid, 8-15 em. long, or longer, 
short-aeuminate, serrate or crenate-serrate, nearly or quite to the 
e usually with two "prominent basal-glands: staminate aments 8-12 em. 
