ORCHIDACEAE. 107 



the inner ones (petals) lateral, alike; the other one (Up) dissimilar, 

 often markedly so, usually larger, often spurred, really anterior, 

 sometimes inferior by the twisting of the ovary or pedicel ; stamens 

 variously united with the style into an unsymmetrical column; 

 anther one sometimes two; pollen more or less coherent into 

 masses (pollinia) ; ovary inferior, usually long and twisted, 3- 

 angled, 1 -celled; ovules numerous, on three parietal placentae; 

 seeds numerous; endosperm none. 



Perfect anthers 2; lip large, sac-like. 133. CYPRIPEDIUM, 107. 



Perfect anther 1. 



Plant saprophytic, without green herbage. 



Flowers spurred, reddish or yellowish. 134. CORALLORHIZA, 108. 



Flowers spurless, white. 135. CEPHALANTHERA, 108. 



Plants with ordinary green herbage. 



Flower and leaf solitary; plant bulbous. 136. CYTHEREA, 108. 

 Flowers several-many in racemes. 



Leaves only two. 137. OPHRYS, 109. 



Leaves more than two. 



Flowers each with a distinct spur. 

 Leaves several, cauline, gradu- 

 ally reduced upwards. 138. LIMNORCHIS, 109. 

 Leaves two, basal; cauline re- 

 duced to bracts. 

 Lateral sepals adnate to the 



base of the lip. 139. PIPERIA, 110. 



Lateral sepals free. 140. LYSIAS, 111. 



Flowers spurless, the lip at most 



saccate. 



Lip with 2 callosities at base; 

 flowers spirally arranged in a 

 dense spike. 141. IBIDIUM, 111. 



Lip without basal callosities. 



Leaves white-reticulated. 142. PERAMIUM, 111. 

 Leaves green. 143. EPIPACTIS, 112. 



133. CYPRIPEDIUM. LADY'S SLIPPER. 



Glandular-pubescent herbs with leafy stems or scapes and 

 tufted roots of thick fibres; leaves large, broad, many-nerved; 

 flowers solitary or several, drooping, large, showy; sepals spread- 

 ing, separate or two of them united under the lip; lip a large 

 inflated sac; column bearing a sessile or stalked anther on each 

 side and a dilated petal-like sterile stamen above, covering the 

 summit of the style; pollinia granular; stigma terminal, broad, 

 obscurely 3-lobed. 



Cypripedium montanum Dougl. Whole plant glandular-pubescent; stems 

 30-50 cm. tall, erect; leaves 4-6, oval, acuminate, 6-12 cm. long; flowers 1-3, 

 pedicelled; sepals brown, usually dark, narrowly lanceolate, 5-6 cm. long; 

 upper petals like the sepals, but narrower and longer, wavy-twisted; lip white, 



