294 American Midland Naturalist Monograph No. 7 



140. Orchidaceae Lindl. — Orchid Family 



1. Lip large, inflated, moccasin-shaped; leaves plaited; fertile anthers 2 



- 1. Cypripediutn 



1. Lip concave or flat, not moccasin-shaped; fertile anther 1. 

 2. Plants with ordinary green foliage at flowering time. 



3. Flowers distinctly spurred, the spur 2 mm or more in length. 



4. Flowers bicolored, the lip white and the sepals and petals purple; 

 leaves 2, basal, oval 2. Orchis 



4. Flowers concolored 3. Habenaria 



3. Flowers spurless. 



5. Flowers large (more than 1 cm broad), solitary or few. 



6. Leaves grass-like; flowers several, racemose, pink-purple 



4. Calopogon 



6. Leaves not grass-like. 



7. Flowers axillary; lip not crested 5. Triphora 



7. Flowers terminal, solitary or few; lip fringed and crested 



6. Pogonia 



5. Flowers smaller, several to many, in spikes or racemes (flowers large 

 in Epipactis) . 

 8. Flowers white or greenish-white. 



9. Inflorescence more or less twisted spirally; leaves alternate or 

 basal, not variegated, often soon withering 7. Spiranthes 



9. Inflorescence not spiral; leaves basal, often whitish-variegated 



8. Coo dyer a 



8. Flowers racemose, greenish or purj^lish. 



10. Leaves 1-2. 



11. Leaf solitary near the middle of the stem, ovate or oval, 



clasping; flowers many, greenish, 2-3 mm long 



9. Malaxis 



11. Leaves two, basal; flowers larger 10. Liparis 



10. Leaves several, clasping, lanceolate to ovate, acuminate or 

 acute; flowers purplish, pendulous in a long, often 1 -sided 



raceme 1 1. Epipactis 



2. Leaves absent at flowering time, or a single basal withered one per- 

 sisting. 

 12. Inflorescence spirally twisted; flowers white or greenish-white; plants 



with 1-several elongate or tuberous-thickened roots 7. Spiranthes 



12. Inflorescence not spirally twisted. 



13. Stem cormose at base, with a solitary basal oval leaf usually with- 

 ering or absent at flowering time; capsules reflexed. 

 14. Flowers spurless; leaf green beneath 12. Aplectrum 



14. Flowers with a long spur; leaf purplish beneath 13. Tipularia 



13. Stem from a cluster of coral-like rhizomes; leaves reduced to scales. 



15. Lip with a callus on each side of the midrib near the base; 



pollinia 4, in two pairs 14. Corallorhiza 



l."). Lip with 5 or 6 prominent ridges down the middle; pollinia 



8, united 15. Hexalectris 



1. Cypripedium L. — Lady's Slipper 



1. Flowering stem leafy. 



2. Sepals oval, not twisted, shorter than the white Hp, which is 3-4 

 cm long, tinged wdth purple; wet woods or springy places, 



