128 CONTRIBUTIONS FROM THE NATIONAL, HERBARIUM. 



Inflorescence racemose; lip not saccate; leaves usually two, not white- 

 netted nor evergreen. 

 Bracts longer than the flowers; perianth united into a magenta-pink 

 hood, the lip white; leaves elliptic, dark green; plants of low rich 



woods. 2. ORCHIS. 



Bracts minute; flowers greenish yellow or madder-purple; leaves ovate, 

 light green; plants of dry woods or damp rocky ravines. 



15. LIPARIS. 

 Stem leafy above the base. 

 Leaves opposite or whorled. 

 Leaves a single pair near the middle of the stem; flowers in a slender 



raceme, small, greenish 12. OPHRYS. 



Leaves usually 5 in a whorl at the top of the stem; flowers one or two, 



large, madder-purple 5. ISOTRIA. 



Leaves alternate. 

 Flowers few, not in racemes. 

 Leaves large, plaited; flowers large, the lip a pink or yellow inflated sac. 



1. CYPRIPEDIUM. 

 Leaves small, not plaited; flowers small, the lip not saccate. 



6. TRIPHORA. 

 Flowers many, in racemes. 

 Lip saccate, not spurred; flowers madder-purple; basal leaves con- 

 spicuously nerved, broadly ovate, reducing upward to lanceolate 



bracts 9. SERAPIAS. 



Lip not saccate, spurred; flowers not madder-purple; leaves not con- 

 spicuously nerved, all lanceolate 3. HABENARIA. 



1. CYPRIPEDIUM L. Lady's-slipper. 



Leaves two, at the base of the stem; lip rosy purple, the opening linear. .1. C. acaule. 

 Leaves several, borne on the stem; lip yellow, the opening round and open. 



2. C. parviflorum. 



1, Cypripedium acaule Ait. Moccasin flower. 

 Bogs, rich woods, or dry pine hills. May. Eastern N. Amer. (Fissipes acaulis 



Small.) 



Nearly white forms are found occasionally, especially in bogs. A plant in flower is 

 shown in plate 20B. 



2. Cypripedium parviflorum Salisb. Yellow lady's-slipper. 

 Banks of ravines or rich woods. May. Northern and eastern N. Amer. (C hir- 



sutum of Biitton's Manual.) 



The large-flowered form (C. pubescens Willd.) is not so common in our region as is 

 the typical small-flowered form. 



Cypripedium hirsutum Mill, was reported from our region by Brereton. (C. specta- 

 bile Salisb.; C. reginae Walt.) 



2. ORCHIS L. 



1. Orchis spectabilis L. Showy orchis. 



Low rich woods. May. Eastern U. S. {Galeorchis spectabilis Rydb.) 

 Sometimes found with only one leaf developed, which would place these plants in 



the related species, 0. rotundifolia Banks, in most manual keys. Our species has 



large bracts longer than the flowers, while 0. rotundifolia has very small bracts. 



Plants in flower are shown in plate 20A. 



