50 KEY AND FLORA 
occasionally escaped from cultivation along streams. Very variable 
and with many hybrids. 
4. S. babylonica L. WrErinc Witiow. A spreading tree, some- 
times 60 ft. or more in height, with drooping branches. Leaves nar- 
rowly lanceolate, taper-pointed, serrate, slightly downy when young 
and becoming smooth with age, green above, pale beneath, often 5-7 
in. long; petioles short, glandular. Catkins on short lateral branches. 
Stamens 2. Style almost none. Capsule sessile, smooth. Introduced 
and cultivated for ornament. 
5. S. cordata Muhl. Heart-Leavep Wititow. A shrub 4-10 ft. 
high, with twigs finely downy or smooth. Leaves oblong-lanceolate, 
taper-pointed, finely and sharply serrate, often tapering but frequently 
obtuse or somewhat heart-shaped at the base, finely downy when 
young (especially on the midrib) but smooth when old; sometimes 
5 in. long; stipules usually large and conspicuous, unequal-sided, 
finely serrate, generally persistent. Catkins with bracts at the base, 
opening earlier than the leaves, the staminate ones very silky, less 
than 1 in. long, the fertile ones in fruit 14-24 in. long. Capsules nar- 
rowly ovoid, pointed. In wet soil and along streams, very variable 
and widely distributed. 
6. S. discolor Muhl. Graucous WiLtow, Pussy WiLtLtow. A 
low tree, sometimes 20 ft. or more in height, with light greenish- 
brown or reddish-brown bark. Leaves oblong-lanceolate, tapering at 
both ends, finely and irregularly toothed or nearly entire, on slender 
petioles, smooth and firm, bright green above, smooth or silvery 
white below, 3-5 in. long; stipules often leaf-like, unsymmetrical, 
usually deciduous. Staminate catkins very white and silky, oblong- 
cylindrical, 1 in. or more long, appearing much earlier than the 
leaves; pistillate catkins 14-24 in. or more long. Stamens 2, with 
long, slender filaments. Capsule cylindrical or nearly so, long-beaked. 
Common in wet meadows or along streams and swamps. 
Il. POPULUS L. 
Trees with prominent scaly buds, twigs more or less angled. 
Leaves usually long-petioled. 
Flowers borne in long, drooping catkins, which appear 
before the leaves; scales of the catkins irregularly cut toward 
the tip. Stamens 8-30 or more. Stigmas 2-4. Capsules open- 
ing early by 2-4 valves. 
1. P. alba L. Srrver-LEAvep Poriar, WuitTE Portar. A large 
tree, sometimes more than 100 ft. high, with smooth greenish-gray 
bark. Leaves broadly ovate, rhombic-oval or nearly orbicular, lobed 
