9(8). Flowers lemon-yellow to bright orange-color 8. H. Integra. 



9. Flowers white or greenish ( 10) 



10(9). Lip uppermost in the snowy-white flowers 9. H. nivea. 



10. Lip lowermost in the flower; flowers greenish or white (11) 



11(10). Lip with a small tubercle or cushionlike callus in the center at or near 

 the base, usually strongly arcuate at the base (12) 



11. Lip sometimes with a thickened keel but never with a tubercle at or near the 



base, pendent, spreading or upcurved (13) 



12(11). Lip subquadrate; petals usually crenulate on the margins 10. H. flava. 



12. Lip linear or linear-ligulate; petals entire 11. H. limosa. 



13(11). Spur scrotiform or strongly saccate to thick-cylindric, usually (but not 

 always) less than two-thirds the length of the lip (14) 



13. Spur slender-cylindric, only slightly clavellate, variable in length, as long as 



or longer than the lip (15) 



14(13). Raceme densely flowered, usually short, thick, congested 



12. H. hyperhorea. 



14. Raceme laxly flowered, elongate, often with the flowers scattered 



13. H. saccata. 



15(13). Leaves very short, ovate, less than 9 cm. long, usually reduced to clasp- 

 ing tubular sheaths 14. H. sparsiflora var. brevifolia. 



15. Leaves ample, usually broadly elliptic to lanceolate, variable in length, never 



reduced entirely to sheaths (16) 



16(15). Lip rhombic-lanceolate, prominently dilated at the base; flowers usually 

 white, rarely greenish 15. H. dilatata. 



16. Lip linear to linear-elliptic or broadly lanceolate, not prominently dilated at 



the base; flowers always greenish, sometimes marked with purple 

 (17) 



17(16). Flowers usually in a densely or loosely flowered slender cylindrical 

 raceme; lip characteristically lanceolate (sometimes broadly lanceo- 

 late) 12. H. hyperborea. 



17. Flowers usually scattered, rarely approximate or produced in an elongate 



raceme; lip characteristically linear (18) 



18(17). Flowers rather small, usually marked or suff'used with purple; lip 4-7.5 

 mm. long, fleshy but usually without a central ridge; column small, 

 usually with a narrow connective, about one-third the length of 

 the dorsal sepal 14. H. sparsiflora var. laxiflora. 



18. Flowers rather large, light green; lip 6-14 mm. long, usually with a fleshy 



ridge in the center below the middle; column large, with a broad 



connective, usually about one-half as long as the dorsal sepal 



14. H. sparsiflora. 



19(8). Lip lobed or angled (sometimes truncate) at the base 10. H. flava. 



19. Lip neither lobed nor angled at the base, either trilobulate or tridentate at 



the apex (20) 



20(19). Spur slender, clavellate, longer than the pedicellate ovary; lip shallowly 



notched at the apex with 3 short equal rounded lobules 



16. //. clavcllata. 



20. Spur scrotiform, much shorter than the pedicellate ovary; lip unequally 



3-lobed at the apex, the acute lateral lobes prolonged beyond the 

 obsolescent middle lobe 17. H. viridis var. bracteata. 



692 



