50 KEY AND FLORA 



occasionally escaped from cultivation along streams. Very variable 

 and with many hybrids. 



4. S. babylonica L. WEEPING WILLOW. 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-LEAVED WILLOW. 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 l-2 in. long. Capsules nar- 

 rowly ovoid, pointed. In wet soil and along streams, very variable 

 and widely distributed. 



6. S. discolor Muhl. GLAUCOUS WILLOW, PUSSY WILLOW. 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 l-2 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. 



II. 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. SILVER-LEAVED POPLAR, WHITE POPLAR. A large 

 tree, sometimes more than 100 ft. high, with smooth greenish-gray 

 bark. Leaves broadly ovate, rhombic-oval or nearly orbicular, lobed 



