318 ORCHIDACEAE 



4. Vanilla planifolia Andr. Leaf -blades oblong to elliptic, 10-18 cm. long: 

 lateral sepals broadly linear to linear-spatulate, 50~5'6 mm. long: petals linear or 

 nearly so: lip 45-50 mm. long, the edge fringed. 



In hammocks, southern peninsular Florida. Also in tropical America. 



17. SERAFIAS L. 



Caulescent herbs, with long roots, the stem very leafy. Leaves with plicate 

 blades. Flowers in a conspicuously bracted raceme. Lateral sepals very inequilateral. 

 Petals smaller than the sepals. Lip free, concave below, constricted between the 

 spreading lateral lobes and the terminal petal-like lobe. Capsules nodding. \Epi- 

 pactis K. Br.] 



1. Serapias gigantea (Dougl.) A. A. Eaton. Stem 3-12 dm. tall: leaf -blades 

 lanceolate to ovate-lanceolate, or those of the lower cauline leaves ovate, 815 cm. 

 long: perianth mainly greenish and purple-veined: lateral sepals obliquely ovate r 

 13-15 mm. long: petals lanceolate, 11-13 mm. long: lip with ovate lateral lobes and 

 a fiddle-shaped middle lobe: capsules 15-20 mm. long. [Epipactis gigantea Dougl.] 



In shaded places, British Columbia to California and Texas. Summer. 



18. PELEXIA Poit. 



Caulescent herbs, with scape-like stems. Leaves various, the lower cauline with 

 dilated long-petioled blades, the upper cauline mere sheathing scales. Flowers in a 

 spike. Perianth greenish. Lateral sepals united at the base and produced into a 

 spur. Petals adnate to the narrow elongated median sepal. Lip elongated, the upper 

 part of the narrow blade crisped: callosities wanting. 



1. Pelexia setacea Lindl. Plant 3-6 dm. tall : blades of the lower cauline 

 leaves oblong to elliptic, 410 cm. long: lateral sepals linear-filiform, 15-17 mm. long, 

 exclusive of the spur: lip 30-37 mm., the body narrowly elliptic or linear-elliptic 

 with a slender tip: capsules 14-17 mm. long. 



In hammocks, southern peninsular Florida. Also in the West Indies. 



19. IBIDIUM Salisb. 



Caulescent herbs. Leaves various, the basal and lower cauline with usually nar- 

 row blades, the upper cauline leaves mere sheathing scales. Flowers in a terminal 

 spiral spike. Perianth pale. Median sepal and petals coherent: lateral sepals erect. 

 Lip erect, or with a spreading tip, bearing 2 basal callosities, the lower portion folded 

 around the very short column. Stigma with a 2 -forked beak. [Spiranthes L. C. 

 Eich. GyrostacJiys Pers.] LADIES' TRESSES. 



Flowers merely alternate, apparently secund from the spiral twisting of the rachis. 

 Stem scaly: leaves with blades basal; blades relatively short and broad, fugacious. 

 Spike strongly spiral: perianth less than 5 mm. long. 



Root solitary: Up white, of an ovate type, erose-crisped from below the middle to the- 



apex. 1. I. Beckii. 



Roots clustered : lip green, except the crisped margins, of an oblong 



type, wavy-crisped at the apex. 2. I. gracile. 



Spike scarcely or not at all spiral: perianth over 6 mm. long. 3. /. longilabris. 



Stem leafy below: leaves with blades mostly near the base of the stem; 



blades narrow, elongated, persistent. 

 Lip pubescent without. 



Leaf-blades semi-terete and channeled. 4. 7. tortile. 



Leaf-blades flat or nearly so. 



Lip of an ovate type, dilated at the base, not laciniate at the apex. 



Leaf-blades elongated, dilated. 5. I. vernale. 



Leaf-blades short, tapering to the apex. 6. /. xyridifolium^ 



Lip of an oblong type, not dilated at the base, laciniate at the 



the apex. 7. /. lanniatum. 



Lip glabrous without. 8. I. praecox. 



Flowers 2-several-ranked, the rachis not conspicuously twisted. 



Lip of an ovate type, the callosities prominent, mostly curved: median 



sepal acute or acuminate. 

 Petals dilated at the base, thus lane olate: spike slender, less than 1.5 



cm. thick during anthesis. 9. /. ovale. 



Petals not dilated at the base, linear: spike stout, over 1.5 cm. thick 



during anthesis. 10. 7. cernuum. 



