la. Flowers in a spike-like obviously twisted raceme; small, yel- 

 lowish or greenish-white, in late summer and autumn (except 

 4a) (Ladies' Tresses) 2. 



Ib. Flowers solitary or in clusters, but never in a twisted raceme 5. 



2a. Flowers in 1 row Ladies' Tresses, Spiranthes gracilis. 



2b. Flowers in several rows 3. 



3a. Lip constricted near the apex 



Ladies' Tresses, Spiraiithes romanzoffiana* 

 3b. Lip not constricted 4. 



4a. Lip yellow; flowers in spring and early summer 



Ladies' Tresses, Spiranthes lucida. 

 4b. Lip white Ladies' Tresses, Spiranthes cernua. 



5a. Brown, purple, or yellow plants, without green color, with scale- 

 like leaves (1 4 dm. high; 'summer) (Coral Root) 6. 

 5b. Plants with normal green color 9. 



6a. Lip white, not spotted Coral Root, Corallorrhiza trifida. 



6b. Lip white, spotted with red 7. 



7a. Lip distinctly 3-lobed Coral Root, Corallorrhiza maculata. 



7b. Lip entire, or barely toothed 8. 



8a. Flower, exclusive of ovary, 4 mm. long 



Coral Root, Corallorrhiza odontorhiza. 



8b. Flower about 10 mm. long. Coral Root, Corallorrhiza striata, 



9a. Leaf 1 or none at flowering time 10. 



9b. Leaves a single pair, basal, or opposite on the stem; never alter- 

 nate on the stem 19. 



9c. Leaves several, all basal, prominently net-veined, and frequently 

 blotched with white (scape 1 4 dm. high; flowers whitish, 

 pubescent, in summer) (Rattlesnake Plantain) 26. 



9d. Leaves 2 or more, on the stem 28. 



lOa. Foliage leaf absent or undeveloped at flowering time, or 

 merely persisting through the winter from the previous 

 year 11. 

 lOb. Foliage leaf present at flowering time 12. 



lla. Flower rose-purple, 3 5 cm. long, solitary or two (1 3 dm. 



high, early summer) Arethusa, Arethusa bulbosa. 



lib. Flowers purplish-green, in racemes, with a spur 2 cm. long 



Crane-fly Orchis, Tipularia discolor. 

 lie. Flowers yellowish, purple tinged, in racemes; -spur none (34 



dm. high, early summer). Putty Root, Aplectrum hyemale. 



12a. Leaf linear or linear-lanceolate 13. 

 12b. Leaf of a broader shape 14. 



13a. Flower solitary or two; leaf just below the flower lla. 

 13b. Flowers in a loose raceme, sometimes only 2; leaf basal 



Calopogon, Calopogon pulchellus. 



14a. Flowers greenish, yellowish, or white 15. 



14b. Flowers pink to purple, often variegated 17. 



