52 ORCHIDS OF JAMAICA 



Similar to S. micrantha with the following differences : Stems 3-9 cm. 1., 

 1-2 mm. br. Leaf longer than the stems, 5-11 cm. 1., 1-2 cm. br. 

 Racemes, 1-3, much longer than leaf, 12-22 cm. 1. Bracts shortly acu- 

 minate, 2-3 mm. 1. Sepals greenish-yellow with purplish tinge at base, 

 apex obtuse, mucronate, 3-nerved, lateral nerves generally meeting the 

 central nerve above in lateral sepals, but not always in median, median 

 2-2-3 mm. 1., 2 -5-2 -6 mm. br., lateral 1-6-2 mm. 1., 2-2-1 mm. br. 

 Petals deep purple, broadly roundish or obovate, upper margin lunate, 

 with very thin points, '7 mm. 1., -9-1-1 mm. br. Lip deep purple, 

 angular-semicircular, -75 mm. 1., 1 mm. br. 



22. PLEUROTHALLIS R. Br. 



Stems clustered or branches of a creeping stem or rhizome, 

 simple, somewhat long, short or very short, with one leaf at the 

 apex, sometimes with one to numerous sheaths below the leaf, not 

 pseudobulbous. Racemes, one to numerous, at the base of the 

 leaf, within the sheath or spathe, simple, with several flowers or 

 laxly few-flowered, or in a few species shortened, 1-3-flowered, 

 and densely crowded, or sometimes solitary. Flowers small, 

 sometimes very small, or in a few species of medium size or rather 

 large, generally on one side of the raceme. Bracts small, shortly 

 tubular. Sepals about the same length, erect or spreading ; the 

 median free or very shortly connate with the lateral at the 

 base; lateral connate at the base or higher into one, entire, 

 2-fid or generally 2-partite, generally concave or slightly gibbous 

 under the foot of the column. Petals shorter or narrower than 

 the sepals, sometimes very small, more rarely about as long as 

 the sepals. Lip shorter than the petals or more rarely a little 

 longer, at the base generally contracted and jointed with the 

 base of the column, 3-lobed ; lateral lobes erect, embracing the 

 column, or small, dentiform, or obsolete ; the median somewhat 

 spreading. Column as long as the lip or a little shorter, 

 semiterete, the angles sometimes membranous-margined, not 

 truly winged, at the base generally produced into a very 

 short foot ; clinandrium small or with a membranous extension, 

 oblique, entire or shortly 3-lobed. Anther terminal or within 

 the margin of the clinandrium, opercular, incumbent, 1-2-celled, 

 pollinia 2, waxy, globose, ovoid or pyriform, free or cohering at 

 the apex by a sparse viscid substance. Capsule sub-globose or 

 ellipsoidal, 3-keeled or 3-cornered. 



Species nearly 600, natives of the mountains of tropical 

 America from the West Indies and Mexico to Brazil and Bolivia. 



I. Spathe at base of racemes large and leathery. 

 Racemes solitary, much longer than leaf. 



Sepals yellow, acute 1. P. longissima. 



Sepals purple, acuminate 2. P. racemiflora. 



Bacemes two or more, clustered, not longer 

 than leaf. 



Lip undivided ; sepals white, gibbous S. P. gelida. 



Lip 3-lobed ; sepals pale yellow 4. P. velaticaulis. 



