3*0 FLORA. 



flowered, becoming 15-25 cm. long in fruit; capsules ovoid, acute, 8-10 mm. long, 

 2-4-valved, shorter than or equalling their pedicels. In moist soil, especially along 

 streams and lakes, Ouebec to Man., south to Fla. and Tenn. April-May. Also 

 called Carolina Poplar. 



Populus deltoides occidentals Rydb. Leaves with longer acumination, broader 

 base and coarser teeth ; young branches light yellow and shining. Sask. to Alb., south 

 to Kan., and N. Mex. 



9. Populus grandidentata Michx. Large-toothed Aspen. (I. F. f. 

 1 169.) A forest tree with smooth, greenish-gray bark, maximum height about 

 20 m., and trunk diameter 7 dm. Leaves of very young plants densely white- 

 tomentose beneath, sometimes 3 dm. long, with irregularly denticulate margins, 

 those of older trees tomentose when young, glabrous when mature, short-acuminate, 

 obtuse or truncate at the base, 6-10 cm. long; petioles slender; bracts silky, irreg- 

 ularly 4-7 cleft; staminate aments 4-10 cm. long, about I cm. in diameter, drooping; 

 pistillate aments somewhat pubescent, dense, 7-12 cm. long in fruit, also drooping; 

 stigma-lobes narrow; capsule conic, acute, 2-valved, about 6 mm. long, papillose. 

 In rich woods, N. S. to Ont. and Minn., south to N. J. and in the Alleghanies to 

 N. Car. and Tenn. April. 



10. Populus tremuloides Michx. American Aspen. (I. F. f. 1170.) A 

 slender tree, with smooth, light green bark, reaching a maximum height of about 

 30 m. and a trunk diameter of 1 m., the young foliage glabrous, excepting the 

 ciliate margins of the leaves. Petioles very slender, causing the leaves to quiver in 

 the slightest breeze; leaves usually short-acuminate at the apex, finely crenulate 

 all around, truncate, rounded or subcordate at base, 2-6 cm. broad, or those of 

 very young plants much larger; bracts silky, deeply 3-5-cleft into linear lobes; 

 aments drooping, the staminate 4-6 cm. long, 6-8 mm. in diameter, the pistillate 

 longer, dense; stigma-lobes linear; capsule like that of the preceding species, but 

 somewhat smaller. In dry or moist soil, Newf. to Hudson Bay and Alaska, soutu 

 to N. J., Ky., Neb., in the Rocky Mountains to Mexico and to Lower California. 

 March-May. 



2. SALIX L. (See Appendix.) 

 Trees or shrubs, with single-scaled buds, the scales with an adherent membrane 

 within, mostly narrow and short-petioled leaves and persistent or early deciduous 

 broad or minute stipules. Bracts of the aments entire. Disk gland-like, small or 

 minute. Staminate aments dense, erect, spreading or drooping. Staminate flowers 

 with 1-10, mostly 2, stamens, their filaments distinct or sometimes united. Pistil- 

 late aments usually erect or spreading. Ovary sessile or short-stipitate. Style 

 short or filiform. Stigmas 2, entire or 2-cleft. Capsule mostly 2-valved. [Name 

 ancient.] About 200 species, of wide geographic distribution throughout the north 

 temperate and arctic zones, a few in the southern hemisphere. Besides the 

 following, many others occur in the northern and western parts of North America. 

 Numerous hybrids between the species have been recorded. 



* Capsule glabrous, or slightly silky when young in Nos. 20-22. 

 1. Trees or larger shrubs with serrate, acute or acuminate leaves. 



Stamens 3-7 ; filaments hairy at the base; bracts caducous, light yellow. 

 Pedicels slender, 3-5 times as long as the gland. 

 Petioles and stipules without glands. 

 Leaves green or pale beneath. 



Leaves narrowly lanceolate ; petioles very short. 



1. S. nigra. 

 Leaves broadly lanceolate ; petioles slender. 



3. S. amygdaloides. 

 Leaves whitish beneath. 2. S. longipes. 



Petioles and stipules with prominent glands. 4. S. lucida. 



Pedicels about twice as long as the gland. 5. S.fragilis, 



Stamens 2. 



Filaments hairy at the base; bracts caducous, yellow. 

 Pedicels in fruit 1-3 mm. long. 



Stigma sessile; leaves linear or lance-linear. 



Leaves finely and almost permanently silky. 



20. S. luteosertcea. 



