154 American Midland Naturalist Monograph No. 7 



Co., Engelmann. [S. wardi Bebb. ; S. longipes 



Shuttlw.] S. caroliniana Michx. 



6. Mature capsules lanceoloid, 5-6 mm long; leaves 

 lanceolate, paler and somewhat glaucous beneath, 

 the petioles usually 5-15 mm long; along streams. 



Apr.-May. Peach-leaved Willow 



-S. amygdaloides Anders. 



5. Capsules 7-11 mm long; shrubs or small trees, 2-4 m tall; 

 swamps and bogs; Lake Co. June. Autumn Willow 



S. serissima (Bailey) Fern. 



4. Ovaries and capsules appressed-silky at first, soon glabrous; 

 leaves linear, subsessile, remotely denticulate; stamens 2; 

 shrub; common along streams. Apr. -June. Sandbar 



Willow. {S. longijolia sensu Muhl., non Lam.] 



S. interior Rowlee 



3. Ovaries and capsules nearly sessile, glabrous; stamens 2; tree; 

 commonly planted and often spontaneous; introd. from 

 Eur. May. The commoner form, var. vitellina (L.) Koch, 

 has glabrous leaves and yellowish twigs. White Willow 



►S'. alba L. 



2. Style distinct, 0.5-1 mm long; ovaries and capsules glabrous. 

 8. Catkins slender, 4-7 mm in diameter at flowering time, 8- 

 18 mm thick in fruit; stamens 2; tree; native of Eur.; often 

 planted, and self-propagating from broken branchlets. 



Apr.-May. Brittle Willow S. fragilis L. 



8. Catkins stout, 8-14 mm in diameter at flowering time, 2-2.5 

 cm thick in fruit; stamens 5; style almost 1 mm long; 

 shrubs; swamps, and along streams and lake shores in the 

 northern third of 111. Shining Willow S. lucida Muhl. 



1. Scales of the catkins brown to black (except S. bcbbiana) , per- 

 sistent; stamens 2. 

 9. Ovaries and capsules glabrous. 



10. Style 0.5-1.5 mm long; scales densely silky-villous; young 



twigs often more or less puberulent ; leaves serrate or 



serrulate. 



1 1 . Flowering catkins appearing before the leaves, sessile or 



nearly so, subtended by a few bracts; leaves pale green 



or more or less glaucous beneath, at least at maturity. 



12. Style 0.5 mm long; capsules 4-7 nmi long, on pedicels 

 1-2 mm long; leaves lanceolate, acuminate, becom- 

 ing glabrous or nearly so ; wet ground, rather com- 

 mon. Apr.-May. [S. rnissouricnsis Bebb; S. cor- 

 data Muhl., non Michx.] S. rigida Muhl. 



12. Style 1 mm long; capsules 7-10 mm long, on pedicels 

 2-4 mm long; leaves ovate-lanceolate, acute; sandy 

 ground, thickets, meadows, and swamps, in the 

 northern third of the state. May. Blue-leaf Willow 



