WILLOW FAMILY 



Swamp Cottonwood, Populus heterophylla 

 long. 



Leaves 4' to 7 



Leaf Buds. — 

 Slightly resinous, 

 ovate, acute, cov- 

 ered with bright red 

 brown scales, one- 

 fourth an inch long 

 and half the size of 

 the flower-buds. 



Leaves. — Alter- 

 nate, four to seven 

 inches long, two to 

 three inches broad, 

 broadly ovate, cor- 

 date or truncate or. 

 rounded with a small 

 sinus at base, finely 

 or coarsely crenate- 

 ly-serrate with in- 

 curved glandular 

 teeth, acute, or short 

 pointed or rounded 

 at apex ; midrib and veins conspicuous, and sometimes downy. 

 They come out of the bud involute, covered with thick white tomen- 

 tum, when full grown are dark green above pale and smooth be- 

 neath. In autumn they turn dull yellow or brown. Petioles terete, 

 slender, tomentose or smooth, two and one- 

 half inches long; stipules caducous. 



Flowers. — March, April. Staminate am- 

 ents are broad, densely flowered, erect at 

 first but finally pendulous, two to two and 

 one-half inches long with stout, brittle, hairy 

 stems. Their scales are narrowly oblong- 

 ovate, brown, divided into many narrow 

 light red brown lobes and falling as the am- 

 ents lengthen. Stamens, twelve to twenty, 

 with slender filaments and large dark red 

 anthers, are inserted on an oblique, slightly 

 concave disk, with spreading border. Pis- 

 tillate aments few-flowered, one to two 

 inches long; ovary ovoid, terete or three- 

 angled ; style short, stout with two or three 

 dilated, two or three-lobed stigmas. 



Fruit. — In maturing the fruiting aments 

 become four to six inches long, pedicels 

 half an inch long; capsules ripen in May, 

 are ovate, acute, red brown, two to three- 

 valved, one-half an inch long ; seed small, 

 dark brown, surrounded by many short, 

 silvery white hairs which are often tinged 

 with orange. 



Part of the Fruiting Ament 

 of Swamp Cottonwood, 

 Populus heterophyllii. 



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