12 



17a. Leaves narrowly lanceolate, 6 15 mm. wide, mostly whorled 



Wood Lily, Lilium pliiladelphicum. 

 17b. Leaves linear, 5 mm. wide or less, almost all alternate 



Wood Lily> Lilium philadelphicum var. andinum. 

 18a. Perianth-segments strongly revolute 



Turk's-cap Lily, Lilium superbum. 

 18b. Perianth-segments half-recurved 



Yellow Lily, Lilium canadense. 

 19a. Flower solitary 20. 

 19b. Flowers in clusters, not solitary 31. 



20a. Stem with a single pair of basal leaves (Dog's-tooth Vio- 

 let) 21. 



20b. Stem with a single whorl of 3 leaves (1 3 dm. high; spring) 

 (Wake Robin, Trillium) 22. 



20c. Stem leafy (Bellwort) 29. 



21a. Perianth yellow Dog^s-tooth Violet, Erythronium americamim. 

 21b. Perianth white, bluish, or pinkish 



Dog's-tooth Violet, Erythronium albidum, 



22a. Flower sessile, red or brown 23. 



22b. Flower peduncled, white or pink, rarely red 24. 



23a. Leaves sessile, sepals spreading Wake Robin, Trillium sessile. 

 23b. Leaves short-petioled, sepals reflexed 



Wake Robin, Trillium recurvatum. 



24a. Ovary with 6 distinct wing-like angles 25. 



24b. Ovary obtusely 3-angled or lobed 28. 

 25a. Stamens distinctly longer than the pistil 26. 

 25b. Stamens equaling or shorter than the pistil 27. 



26a. Stigmas erect or nearly so, slender 



Wake Robin, Trillium grandifloruni. 

 26b. Stigmas strongly recurved or spreading 



Wake Robin, Trillium erectum. 

 27a. Filaments about as long as the anthers 



Wake Robin^ Trillium cernuum. 

 27b. Filaments half as long as the anthers or shorter 



Wake Robin, Trillium declinatum. 



28a. Leaves obtuse; petals obtuse, white 



Dwarf White Trillium, Trillium niyale. 

 28b. Leaves acuminate; petals acute, purple-striped at base 



Painted Trillium, Trillium undulatum. 



29a. Leaves sessile (3 6 dm. high; flowers yellow, spring) 



Bellwort, Oakesia sessilifolia. 



29b. Leaves perfoliate. (4 6 dm. high; flowers yellow, in spring) 30. 



30a. Leaves minutely pubescent beneath 



Bellwort, Uvnlaria grandiflora. 

 30b. Leaves glabrous and all glaucous 



Bellwort, Uvularia perfoliata. 



