elliptic to oblong-lanceolate, obtuse to acute; lateral sepals oblong-Ianceolate to 

 lanceolate, somewhat falcate, obtuse to acute; petals linear, obtuse, 6.5-12 mm. 

 long, 1-2 mm. wide; lip pandurate, with the thin suborbicular base strongly con- 

 cave and prominently veined, conspicuously constricted above the middle, some- 

 what dilated above the constriction, 7-1 1 mm. long, 5 mm. wide across the lower 

 half, strongly arcuate-recurved near the apex in natural position; basal callosities 

 minute; column 2-3 ,mm. long. 



In moist or wet situations in bogs, marshes, meadows, salt flats, thickets, on 

 sandy-gravelly beaches and occasionally in dry woods and on dry open hillsides, 

 in N. M. (Sandoval Co.) and Ariz. (Apache, Coconino and Graham cos.), July- 

 Oct.; Nfld. to Alas., s. to N.E., N.Y., Neb., N.M., Ariz, and Calif.; Ire. 



2. Spiranthes cernua (L.) Rich. Nodding ladies' tresses. Fig. 372. 



Plant erect, glabrous below, downy-pubescent above, occasionally stoloniferous 

 (especially in swamp areas), 1-5.5 (-9.5) dm. tall; roots slender or coarse, fleshy; 

 leaves mostly basal or fugacious, linear to lanceolate, acute to acuminate, 5-40 cm. 

 long, 5-20 mm. wide; spike densely flowered, compact, consisting of rather small 

 nodding flowers in 2 to 4 (rarely 1) spiral or vertical ranks, 3-18 cm. long, 2-3 cm. 

 in diameter; floral bracts ovate to lanceolate, acuminate-attenuate, 8-15 mm. long; 

 flowers white, sometimes marked with green or cream-tinged, usually fragrant of 

 vanilla; perianth parts somewhat downy on the outer surface; sepals oblong- 

 lanceolate, obtuse to subacute, 6-13.5 mm. long, to about 3 mm. wide, the lateral 

 sepals free; petals coherent with the dorsal sepal, linear to linear-lanceolate, 

 obtuse to acute, 6-13.5 mm. long, 1-2 mm. wide; lip ovate-oblong to oblong, 

 arcuate-recurved, sometimes rhombic with the basal half dilated, with the apical 

 margins erose or crisped, 6-14 mm. long, 3-8 mm. wide across the base; basal 

 callosities prominent, pubescent; column stout, 3-5 mm. long. 



Var. cernua. Lip ovate-oblong to oblong, mostly 6-1 1 mm. long. Ibidium cernuum 

 (L.) House. In swamps, wet woods, stream bottoms, grassy seepage slopes, in 

 Okla. (Ellis and Payne cos.), cen. and e. Tex. and N.M. (Rio Arriba Co.), July- 

 Dec; N.S., and Ont., s. to Fla., w. to Minn., S.D., Neb., Kan., Okla., Tex. and 

 N. M. 



Var. odorata (Nutt.) Correll. Fragrant ladies' tresses. The thickish lip of var. 

 odorata is broadly ovate instead of being oblongish as in var. cernua. Gyrostachys 

 odorata (Nutt.) O. Ktze. This variety occurs sparingly throughout the area of 

 distribution of var cernua. It attains its maximum development in the southeastern 

 states where it is commonly found in stoloniferous colonies in water and mud of 

 swamps, marshes, and along wooded rivers and streams. 



3. Spiranthes gracilis (Bigel.) Beck. var. gracilis. Green-lip ladies' tresses. 



Fig. 373. 



Plant slender, essentially glabrous throughout, rarely sparsely pubescent above, 

 1.8-7.5 dm. tall, occasionally two or three plants produced from the same root- 

 stock; roots fasciculate, stout, short, fleshy; leaves basal, fugacious, broadly ovate 

 to elliptic or ovate-lanceolate, short-petioled; lamina 1.5-6.5 cm. long, 1-2.3 cm. 

 wide; spike slender, densely or loosely flowered, strongly spiraled or occasionally 

 secund, rarely bifurcate, 3-26 cm. long; floral bracts ovate to ovate-lanceolate, 

 acute to long-acuminate, 5-10 mm. long; flowers small, white with a green stripe 

 in the center of the lip, in a single rank; perianth 4-6 mm. long; sepals and petals 

 about equal in length, 4-5.5 mm. long; dorsal sepal elliptic-oblong to oblong- 

 lanceolate, obtuse to acute; lateral sepals lanceolate, acute to somewhat acuminate; 

 petals coherent with the dorsal sepal, linear, obtuse to subacute; lip oblong- 

 quadrate to elliptic-oblong, 4-6 mm. long, about 2.5 mm. wide, with the slightly 

 grooved central . portion conspicuously green, the apical margins crenulate to 

 somewhat fringed-erose; basal callosities short, erect; column 2-3 mm. long. 



727 



