426 Salic ace.t:. 



c r'lipsiiles sliibrous : leaves 



d Obloiig-liincealate, acute at apex S. balsamifera, 



d- Linear-lanceolate ; branchlets long and pendent S. Babylonica. 



d" Lanceolate to oblauceolate ; branchlets not pendent, 

 e (ilabrous 



Bright or reddish yellow ; leaves glaucous beneath S. vitellina. 



Ijight brown ; leaves silky pubescent S. alba. 



e- Brownish pubescent S. Missouriensis. 



c" Capsules hairy: style short; leaves ovate-lanceolate to oblong, acute 



Glabrous and glaucous beneath ; branchlets usually glabrous ; pedicel of ovary shorter 



than the scale S. discolor. 



Pubescent beneath : branchlets pubescent ; pedicel ot ovary longer than scale. 



S. Bebbiana. 

 For apccicfi sec pp. 7-'f-!)3 ami ilic foUotiing : 



Balsam AVillow. Salix bahatnifcra Barr. A species of boreal distribution ranging 



from about the latitude of Mt. Washington northward and usually shrubby, but in the 



vicinity of Ft. Kent, Me., has been found to attain the height of 2.5 ft. with trunk 12-1-1 in. 



in diamater. It is characterized as follows : 



Leaves elliptic to ovate, 2-4 in. long, rounded or subcordate at base, usually acute or 

 obtuse at apex, finely glandular-serrate, thin at first, finally rigid, glabrous, dark green above, 

 paler, glaucous and prominently I'eticulated beneath : stipules usuall.v none ; petioles slender 

 Va in. or less in length. Flowers: aments expanding with the leaves on leafy -bracted 

 branchlets, the staminate dense ; stamens 2, with free filaments : pistillate rather loose ; scales 

 rose-colored, villous, persistent ; style very short. Fruit capsules narrow-ovoid, long-stalked. 



White Willow. tSaliv alba L. A large European tree willow sparingly escaped in 

 this country and differs from the <S'. riteUiiia mainly in having more ashy gray ancl silky 

 pubescent leaves, which gives a whitish effect to its foliage, and more brownish branchlets. 

 Var. ecentlea Koch., also occasionally found, has more glabrous dull bluish green leaves and 

 olive branchlets. 



Bebb Willow. Kalix Behhinana. Sarg. (S. roxtrata Rich.). A large shrub or small bushy 

 tree, occasionally 2-5 ft. in height, with a trunk 6 or 8 in. in diameter, ranging from Pennsyl- 

 vania to the Arctic regions, and from the St. Lawrence liiver to Alaska, and in botanical 

 characters is close to <S'. discolor (see pp. 92-93) but differs in having leaves uusally tomen- 

 tose or pubescent beneath; pedicel of the ovary longer than the scale and .branchlets pubes- 

 cent. 



THE POPLARS AND COTTONWOODS. Genus POPULUS L. 



Trees of usually large size, rapid growth, with scaly and usually resin-coated buds and 

 bark pale at first but furrowed when old and rich in tannin. The sticky resin of these buds 

 is gathei'ed by honey bees for sealing crevices in their hives, the material which bee-keepers 

 call " propolis." About twenty-five species are recognized of which approximately half are 

 natives of North America ranging from the Atlantic to the Pacific and from the Arctic Circle 

 to the tropics. 



The Poplars are the oldest known dicotyledonous plants, being represented among the 

 . ^ "^^ssiJs ot the cretaceous formations. 



Leaves lance-ovate to orbicular or deltoid, involute in the bud, usually with long stalks 

 more or less laterally compressed causing their easy agitation by the winds ; stipules small 

 and caducous ; branchlets terete or angled ; winter buds pointed, more or less resin-coated 

 and covered with several thin imbricated scales. Flowers expanding with or before the leaves 

 in stalked drooping aments Avhich elongate Avhile maturing, with thin obovate stipitate 

 fimbriated caducous scales, more crowded on the staminate aments ; pistillate aments with 

 broad cup-shaped, usually oblique, stipitate and persistent disk ; stamens 4-flO, with short free 

 filaments ; anthers purplish ; ovary sessile with short style and entire digitate or broadly 

 2-4-lobed stigma. Fruit maturing often before the full growth of the leaves, in usually 

 drooping racemes and with subglobose to ovoid-oblong capsules subtended by the persistent 

 disk and dehiscent by 2-4 I'ecurved valves: seeds small, brown and provided with abundant 

 cottony hairs. 



The name is the ancient Latin name of the Poplar. 



KEY TO THE SPECIES. 

 a Buds coated with a sticky resin ; leaves 



b Broadly deltoid, acute or acuminate at apex 



Very wide-cordate to truncate at base ; buds large P. deltoide*. 



V^ry wide-cuneate to truncate at base : buds comijaratively small. 



P. dilatata. 



b' Rhombic-lanceolate, green both sides, long-pointed P. acuminata. 



V Ovate-lanceolate, green both sides, short-petiolate P. angustifolia. 



