GENUS i. 



WILLOW FAMTT.Y. 



ii. Populus Sargentii Dode. 



Western Cottonwood. Fig. 



1450. 



P. deltoides occidentalis Rydb. Mem. N. 



Y. Bot. Card, i: 115. 1900. 

 P. Sargentii Dode, Mem. Soc. Hist. Nat. 



Autun 18: [reprint 40]. 1905. 

 Populus occidentalis Britton ; Tillotson, 



Rep. Board. Agric. Nebr. 1906-7: 218. 



Similar to P. deltoides, the bark 

 thick and gray, the twigs smooth, 

 greenish to light yellow. Leaves 

 glabrous on both sides when mature, 

 broadly triangular-ovate, often wider 

 than long, subcordate to truncate at 

 the base, rather long-acuminate at the 

 apex, the margins coarsely and 

 bluntly toothed; petioles flattened, 

 about as long as the blades ; stami- 

 nate aments 2'-$$' long, not very 

 dense; ripe pistillate aments 5' long 

 or more; capsules ovoid, 5"-?" long, 

 longer than their pedicels. 



River bottoms, Saskatchewan to North 

 Dakota, Nebraska, Kansas and New 

 Mexico. Wood soft and brownish ; 

 weight per cubic foot about 22 Ibs. 

 March-April. 



2. SALIX [Tourn.] L. Sp. PI. 1015. 1753. 



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 i-io, mostly 2, stamens, their 

 filaments distinct or sometimes united. Pistillate 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, some 60 others occur in the northern 

 and western parts of North America. Many hybrids are known. Type species : Salix alba L. 



A. Trees, or large shrubs mostly more than 3 high (no. 24 smaller), 

 i. CAPSULE GLABROUS, OR IN NOS. 7 AND 8, SILKY-PUBESCENT, NOT TOMENTOSE. 



Stamens 3-7 (sometimes 2 in no. 6) ; 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. 

 Leaves broadly lanceolate ; petioles slender. 

 Leaves whitish beneath. 



Petioles and stipules with prominent glands. 

 Summer-fruiting ; leaves green beneath. 

 Autumn-fruiting ; leaves pale beneath. 

 Pedicels about twice as long as the gland. 

 Stamens 2. 



Filaments hairy at the base ; bracts caducous, yellow. 



Pedicels in fruit 1-3 mm. long; native shrubs or small trees. 

 Leaves entire, finely and almost permanently silky. 

 Leaves denticulate, coarsely silky when young, glabrate in age. 

 Pedicels in fruit less than i mm. long ; large introduced trees. 

 Branches not drooping ; leaves lanceolate. 

 Branches drooping ; leaves linear-lanceolate. 

 Filaments glabrous ; bracts persistent. 

 Mature leaves glabrous. 



Length of leaf-blade less than three times its breadth. 

 Mature leaves thin, dull. 



Mature leaves thick, firm, dark green and shining above. 

 Length of leaf-blade three times its breadth or more. 

 Mature leaves densely silky-pubescent ; capsule subsessile. 



2. CAPSULE TOMENTOSE. 



Filaments united ; capsule sessile; style none.. 

 Filaments distinct. 



1. 5". nigra. 



2. S. amygdaloides. 



3. S. Wardi. 



4. 5". lucida. 



5. S. serissima. 



6. S.fragilis. 



7. S. exigua. 



8. S. interior. 



9. 5". alba. 



i o. 5". babylonica. 



n. S. pyrifolia. 



12. S. glaucophylla. 



13. S. cordata. 



14. S.adenophylla. 



15. S.purpurea. 



