54 Orchidaceae 



tuberous roots, sheathing entire leaves, some- 

 times reduced to scales, the flowers perfect, 

 irregular, bracted, solitary, spiked or racemed. 

 Perianth superior of 6 segments, the 3 outer 

 (sepals) similar or nearly so, 2 of the inner 

 ones (petals) lateral, alike; the third inner 

 one (lip) dissimilar, often markedly so, usu- 

 ally larger and often spurred; stamens and 

 style variously arranged. An extensive 

 family with great diversity of flower form, 

 and habit of growth. Most abundant in the 

 tropics, represented in the region as follows: 



Perfect anthers 2 ; lip large, sac-like. Cypripedium. 

 Perfect anther i. 



Plants saprophytic, without green herbage. 



Corallorhiza. 

 Plants with ordinary green herbage. 



Flower and leaf solitary ; root bulbous. Cytherea. 

 Flowers several to many in racemes. 

 Leaf only i. 



. Flowers white with purple spots. Orchis. 



Flowers greenish. Lysiella. 



Leaves only 2, cauline. Ophrys. 



Leaves more than 2. 



Stem leaves reduced to bracts. 



Basal leaves white veined. Peramium. 



Stem leaves not reduced to bracts. 



