40 American Midland Naturalist Monograph No. 4 



Leaves whitish below. 



Leaves finely toothed, at first shghtly silky, becoming smooth; styles very short 



or none; found m Rocky Mountam National Park 16. 5. peliolaris. 



Leaves not toothed or scarcely so, hairy on both sides, at least when young; 



styles I mm. or more long; found in Rocky Mountain parks 



1 7. 5. pseudolapponum. 



b. Scales of catkins brown or blackish, at least at tips, persistent. 



Leaves about equally hairy on both sides, at least when young. 



Leaves somewhat whitish below, not toothed or scarcely so. 



Leaves gray-woolly; scales of catkins dark at tips; found in Rocky Moun- 

 tain parks 17. S. pseudolapponum. 



Leaves long silky-hairy; scales of catkins dark; found in Pacific Slope 



parks 18. 5. oresfera. 



Leaves green on both sides, densely long-hairy, not toothed or with fine glandu- 

 lar teeth. 



Leaves 1 inch or less long (or up to 2 inches in var.), silvery-hairy, not 



toothed; Rocky Mountain parks (except Glacier) 



19. 5. Wolfi & var. 



Leaves mostly 1 to 2'/2 (or 3J/2) inches long, more or less glandular- 

 toothed, long-hairy or woolly; found in Pacific Slope parks or at 

 Glacier National Park. 



Leaves about 1 to 2J/2 inches long; styles 1 to 1 J/2 mm. long; mostly 

 Pacific Slope species. 



Filaments hairy below; capsules softly gray-hairy; in Sierra 



Nevada parks and at Crater Lake 20. 5. Easimoodiae. 



Filaments smooth; capsules smooth or very finely woolly; found 



in Northwest and in Glacier National Park 



21 . 5. commutala. 



Leaves l'/2 to 3 J/2 inches long; styles V/2 to 2J/2 mm. long; found in 



Glacier National Park 22. 5. Darrattiana. 



Leaves smooth, or hairy only below (sometimes thinly hairy above also). 



Capsules smooth (sometimes thinly hairy in 5. Barcla\}i and 5. lasiolepis) ; 

 leaves smooth on both sides at maturity or sometimes hairy below 

 (sometimes thinly hairy above in 5. Barclayi.) 



Styles 1 mm. or more long. 



Styles IJ/2 to 2J/2 mm. long; leaves glandular; found in Yellowstone 



and Grand Teton National Parks 23. 5. Trveedyi. 



Styles not over II/2 mm. long; leaves not glandular. 



Leaves smooth on both sides (sometimes thinly hairy above in 

 S. Barcla^i). 



Branchlets finely hairy or nearly smooth; catkins borne on 

 distinct stalks ; found in the Northwest and Yel- 

 lowstone National Park 24. S. Barcla^i. 



Branchlets smooth and shining; catkins scarcely if at all 

 stalked. 



Stamens with filaments distinct; found in parks of the 



Rocky Mountains 25. 5. pseudomonlicola. 



Stamens with filaments joined at base; found in parks 



of the Northwest 26. 5. Piperi. 



