OECHIDACEAE 311 



Sepals more strongly developed than the petals. 38. PLEUROTHALLIS. 



Flowering stem lateral. 



Leaves convolute in the bud. 



Lip encompassing the column or growing to it, without a 

 sac: pollinia 4 or 8, with caudiculae, but without stipes. 

 Pollinia 8: lip sessile, the crests on the middle lobe. 39. BLETIA. 



Pollinia 4: lip stalked, the crests below the middle lobe. 40. APLECTRUM. 

 Lip articulated to the foot of the column, or forming with it a 

 spur: pollinia 2 or 4, without caudiculae but with 

 short stipes. 



Lip contracted into a claw: foot of the column slender. 41. CYRTOPODIUM. 

 Lip sessile, the base truncate or cuneate: foot of the column 



dilated or abruptly narrowed at the base. 

 Lip crestless, deeply 3-lobed, the lateral lobes widely 

 spreading: foot of the column concave and grooved, 

 not dilated, the margins thick. 42. TRIORCHOS. 



Lip with a crest of nipple-like papillae, shallowly 

 3-lobed: foot of the column flat, thin and dilated, 

 the margins thin. 43. PLATYPUS. 



Leaves duplicate in the bud. 



Leafy shoots with a limited growth, the single year's growth 



sympodially arranged. 



Anther upright. 44. MACRADENIA. 



Anther inclined. 



Perianth spurred. 45. IONOPSIS. 



Perianth not spurred. 46. ONCIDIUM. 



Leafy-shoots with unlimited growth. 



Pollinia sessile: lip long-spurred; the apex or the middle 



lobe again lobed. 47. POLYRHIZA. 



Pollinia stalked: lip saccate or short-spurred, the apex entire. 

 Flowers in a stiff spike: lip partially adnate to the 



column, usually saccate at the base. 48. CAMPYLO CENTRUM. 



Flowers in a lax raceme: lip sessile at the base of the 



column, with a globular spur. 49. HARRISELLA. 



1. CYPRIPEDIUM L. 



Caulescent herbs with fibrous roots. Leaves several: blades plaited. Lip a 

 horizontal sac. Stamens appressed, the free tips directed forward. Spring. LADIES* 

 SLIPPER. MOCCASIN FLOWER. 



Sterile stamen with the stalk wholly adnate to the column, the blade rounded at the base: column 



wings short and broad: lip longer than the sepals and petals. 1. C. reginae. 



Sterile stamen with the stalk partially adnate to the column, the blade not 

 rounded at the base: column-wings long and narrow: lip shorter than the 

 sepals and petals. 

 Sterile stamen with a triangular-ovate blade, less than 1 cm. long, obtuse: 



lip pale yellow: flowers fragrant. 2. C. parvijlorum. 



Sterile stamen with an oblong-ovate or ovate-lanceolate blade over 1 cm. long, 



acute: lip golden yellow: flowers not fragrant. 3. C. pubescens. 



1. Cypripedium reginae Walt. Stem 3-6 dm. tall: leaf -blades oval or elliptic, 

 8-20 cm. long: sepals white, oblong to oval: petals white, lanceolate, barely as long as 

 the sepals: lip about 4 cm. long, with purple and white stripes: capsule-body 3-4 cm. 

 long. 



In swamps and woods, Nova Scotia to Ontario, Minnesota and Georgia. 



2. Cypripedium parviflorum Salisb. Stem 3-5 dm. tall: leaf -blades elliptic 

 to oval, 6-12 cm. long: sepals lanceolate to oblong-lanceolate, 2.5-3.5 cm. long; petals 

 longer and narrower than the sepals: lip 1.5-2.5 cm. long: capsule-body 2-3.5 cm. 

 long. 



In woods and on hillsides, Newfoundland to British Columbia, Georgia, Missouri and 

 Washington. 



3. Cypripedium pubSscens Willd. Stem 3-7 dm. tall: leaf -blades oblong or 

 elliptic, 9-15 cm. long: sepals ovate-lanceolate or oblong-ovate: petals linear or 

 attenuate, longer than the sepals: lip 3.5-5 cm. long: capsule-body 3.5-4 cm. long. 

 [C. Jiirsutum Morong. Not Mill.] 



In woods and on banks, Nova Scotia to Ontario, Minnesota, Georgia and Nebraska. 

 Specimens of a large-flowered form of this species or a related undescribed species have 

 been collected near David, Mississippi. 



2. FISSIPES Small. 



Acaulescent herbs, with fibrous roots. Leaves mostly 2: blades plaited. Lip a 

 drooping sac. Stamens spreading, the free tips at right angles to the column. 

 MOCCASIN FLOWER. PURPLE SLIPPER. 



