42 American Midland Naturalist Monograph No. 4 



Eastern species found on Isle Royale. 



Leaves softly hairy below and also above when young, 

 wavy-margined but not toothed; catkins egg- 

 shaped to elliptic, '/2 *o ''/2 inches long 



37. S. humilis. 



Leaves smooth below, irregularly scallop-toothed; cat- 

 kins cylindric, I to 3 inches long ....38. 5. discolor. 



Leaves narrowly lance-shaped, with slender-pointed tips, finely 

 toothed; catkins narrowly egg-shaped, broad and loose 

 in fruit, about ^ to IJ/2 inches long; found in Rocky 



Mountain and Isle Royale National Parks 



16. 5. peiiolaris. 



Catkins appearing with the leaves, mostly leafy-bracled at base; styles 

 evident or none. 



Leaves smooth on both sides. 



Leaves egg-shaped to reverse-egg-shaped or oblong, I/2 to 2 

 inches long; filaments of stamens smooth; capsules 



not stalked, the style 1 mm. or more long 



39. S. planifolia. 



Leaves elliptic-lance-shaped to reverse-lance-shaped, l'/'2 'o 

 4 inches long; filaments of stamens finely hairy at 

 base; capsules on stalks l'/2 to 2 mm. long, the 

 styles very short 40. 5. Lemmoni. 



Leaves hairy below. 



Leaves mostly |/2 inch or more wide; silky below. 



Stamens 2 ; found east of Great Western Divide. 



Branchlets hoary with a dense white bloom; styles 



1 to IJ/2 mm. long 41. 5. subcoerulea. 



Branchlets smooth or becoming so; styles ]/2 *o 1 



mm. long 42. 5. Drummondiana. 



Stamens single; found in Pacific Slope parks. 



Branchlets slender, rarely hairy; anthers purple 



43. 5. siichensis. 



Branchlets stoutish, more or less hairy; anthers 



yellow 44. 5. Coulleri. 



Leaves mostly less than '/2 inch wide, silky or woolly- 

 velvety below. 



Branchlets smooth; leaves silky-hairy below; found in 



Yosemite and Sequoia National Parks 



45. S. Jepsoni. 



Branchlets at first white-woolly or hairy, becoming 

 smooth ; leaves white below with fine wool or 

 velvety hairs; found east of Great Western 

 Divide. 



Leaves dull below with fine white wool ; anthers 



red; found in Glacier National Park 



46. 5. Candida. 



Leaves lustrous below with velvety hairs; anthers 



yellow; found on Isle Royale 



47. S. pellita. 



