164 Karl M. Wiegand and Arthur J. Eames 



d. Catkins 1.5-2 cm. long, recurved; twigs very slender, drooping. 



6. S. blanda 

 d. Catkins 2-5 cm. long, not recurved; twigs stouter, sometimes flexuous but 

 not drooping. 

 e. Young leaves glabrous, rarely sparsely pilose; twigs olive-green, very 



fragile at base. 7. S. fragilis 



e. Young leaves silky pubescent; twigs tough or somewhat fragile at base. 

 /. Twigs green or brownish green. 8. 5\ alba 



f. Twigs yellow or reddish yellow. 8a. 5". a., var. vitelline! 



a. Nectary 1 ; scales with pinkish, reddish, brownish, or black tips, not uniformly 

 yellow or pale except sometimes in nos. 9 and 10; catkins either on leafy- 

 bracted branchlets or nearly sessile ; shrubs. 

 b. Filaments free or fused less than half their length, glabrous ; catkins strictly 

 alternate. 

 c. Scales uniformly pale, or with pink tips. 



d. Flowering branchlets leafy, the leaves that develop below the catkins equal- 

 ing or surpassing the catkins ; young leaves early becoming glabrous ; 

 catkins not constricted at base; scales obovate or oblanceolate, sparsely 

 hairy or glabrous; small shrubs of bogs. 9. S. pedicellaris 



d. Flowering branchlets not really leafy, the 1-4 bracts less than half the length 

 of the catkins; leaves pubescent; young catkins constricted at base; scales 

 oblong or spatulate, hairy; large shrubs of low grounds. 



10. S. Bebbiana 

 c. Scales with dark tips (dark red, brown, or black). 

 • d. Anthers and nectary deep red (blackish when dry). 12. S. Candida 



d. Anthers and nectary yellowish or at least pale, or the anthers orange-red 

 when young. 

 e. Catkins with some (often small) herbaceous bracts at the base, in flower 

 as the leaf buds are opening. 

 /. Catkins 10-15 (18) mm. long; young foliage tawny- or rusty-silky; 

 anthers (dry) 0.4-0.5 mm. long; hairs of the scales silky, hardly 

 curled or matted ; twigs tough at base. 13. .S". petiolaris 



f. Catkins (15) 18-28 mm. long; young foliage glabrous or white-hairy. 

 g. Anthers (dry) 0.4-0.5 mm. long; young foliage white-silky; hairs of 

 the scales silky, hardly curled or matted ; twigs brittle at base. 



14. .S". sericea 

 g. Anthers (dry) 0.6-0.8 mm. long; young foliage glabrous, or, if 

 white-pubescent, hardly silky; hairs of the scales curly or matted, 

 hardly silky; twigs tough at base. 11. S. cordata 



e. Catkins without bracts at the base, in flower before the leaf buds begin to 

 open. 

 /. Catkins 25-50 mm. long, not recurved ; one-year-old twigs glabrous ; 



large shrubs of wet places. 15. 5". discolor 



f. Catkins 10-25 mm. long, usually recurved; one-year-old twigs usually 

 pubescent at the tips and the upper nodes ; small shrubs of dry places. 



16. S. hnmilis 

 b. Filaments fused nearly or quite to the anthers, pubescent ; catkins often sub- 

 opposite. 17. S. purpurea 



Key based on pistillate flozcers and fruit 14 



a. Scales pale or yellow, without dark tips, caducous ; catkins terminal on leafy lateral 

 branchlets. 



14 Varieties based chiefly on foliage are omitted. Only pistillate catkins are referred to in 

 this key. 



