3(2). Lip ovate-oblong, usually slightly constricted at about the middle and then 

 somewhat dilated at the apex, mostly less than 1 cm. long; leaves 

 basal or only on the lower part of the stem 2. S. cernua. 



3. Lip broadly rhombic-ovate, with the basal half dilated, tapering to the obtuse 



or subacute apex, often as much as 1.4 cm. long; leaves often 

 extending up the stem 2. S. cernua var. odorata. 



4(1). Basal leaves widely spreading, with the relatively short and broad blades 

 having a distinct petiole, ovate to narrowly oblong-elliptic, either 

 persistent or fugacious (marcescent) (5) 



4. Basal leaves erect, ascending, narrow, linear, narrowly lanceolate or oblong- 



elliptic, without a petiole, the lower portion sheathing the stem, 

 either persistent or fugacious (7) 



5(4). Plant with a densely pubescent spike; lip deeply fringed and with a promi- 

 nent tuft of hairs on the disk near the apex; leaves usually per- 

 sistent; flowering in the spring 3. S. gracilis var. brevilabris. 



5. Plant essentially glabrous throughout (6) 



6(5). Lip with a broad green stripe on the central portion of the disk; leaves 



fugacious or marcescent; usually flowering in the fall 



3. S. gracilis. 



6. Lip with a broad yellow stripe on the central portion of the disk; often flecked 



with green; leaves mostly persistent; usually flowering in the spring.. 

 3. S. gracilis var. ftoridana. 



7(4). Flowers secund (rarely slightly spiraled); lip from a broad base tapering 



to the obtuse apex, 6-9.5 mm. long; basal leaves fugacious 



4. S. longilahris. 



7. Flowers strongly spiraled; lip ovate, orbicular-quadrate, oblong or oblong- 



quadrate; basal leaves persistent or fugacious (8) 



8(7). Lip oblong-elliptic to oblong, with parallel lateral margins or sometimes 

 broadest at the distal end, membranaceous (9) 



8. Lip ovate to ovate-oblong or ovate-elliptic, broadest at or near the base, 



usually fleshy-thickened; spike more or less pubescent with capitate 

 or sharp-pointed hairs (10) 



9(8). Lip usually veined with green; spike subglabrous or very sparsely pubes- 

 cent with usually capitate hairs; distribution in eastern Texas 



5. S. praecox. 



9. Lip not veined with green; spike densely pubescent with long hairs; distribu- 



tion in southern Arizona 6. S. graiuinea. 



10(8). Spike densely pubescent; ovaries usually covered by a thick mat of 



reddish-brown sharp-pointed hairs; lip ovate to ovate-elliptic 



7. S. vernalis. 



10. Spike more or less pubescent with capitate hairs; lip ovate-oblong, often from 



a suborbicular base, conspicuously laciniate along the apical mar- 

 gins 8. S. X laciniata. 



1. Spiranthes Romanzoffiana Cham. Hooded ladies' tresses, western ladies' 

 TRESSES. Fig. 371. 

 Plant erect, glabrous below, somewhat glandular-pubescent above, 8-55 cm. tall; 

 roots fasciculate, long, fleshy; leaves mostly basal, linear to oblanceolate or 

 oblong-lanceolate, 5-26 cm. long, 6-13 mm. wide; spike densely flowered, cylindri- 

 cal, composed of three spiral ranks of flowers, 3-12 cm. long, 1.5-3 cm. in 

 diameter; floral bracts ovate to ovate-lanceolate, acuminate, semitranslucent, 

 nervose, 1.2-2.5 cm. long; flowers white or creamy white, tubular, dilated and 

 ringent above the middle; sepals and petals connivent and forming a hood over the 

 column; sepals 6.5-13 mm. long, 3-4 mm. wide near the base; dorsal sepal oblong- 



724 



