46 NATIVE BRITISH ORCHIDACE^ 



The sub-family contains over 500 genera and 17,000-20,000 species (Schlechter, 

 Mon. Orch. Eur. p. 71), and presents an extraordinary variety of floral construction. 

 Evolution has been extremely active, on many distinct lines, in marked contrast with 

 the Diandras, in wliich it has stopped at four genera. The Monandrse embody a 

 number of totally diiferent ideas, the devices employed to secure the transport of 

 pollinia having sometimes baffled the great Darwin himself. 



The sub-family embraces two great groups: 



(i) Epiphytes, normally growing on trees, with roots exposed to the air. With 

 very few exceptions these are tropical, and far surpass the ground orchids in number. 



(2) Terrestrial or ground orchids, chiefly found in the temperate zones, but also 

 in the tropics, the roots or tubers of which are buried in the soil. All the European 

 orchids are terrestrial, a class mostly confined to the temperate regions of Europe, 

 Asia and N. Africa, comparatively few genera extending to N. America. 



Tribe I NEOTTIEiE Lindl. 



Only fertile anther at apex of column, often hinged. Pollinia without basal caudicles. 

 Rostellum usually present. Plants with thickened fleshy fungus-infected and partially 

 tuberised roots, without tubers, but often with rhizomes. 



In Cephalanthera there is no rostellum. It appears to be absent from Epipactis in 

 E. Muelleri Godf. (continental only), and evanescent or sometimes absent in the case 

 of E. leptochila and E. dimensis. In Spiranthes autumnalis the roots are usually two, 

 looking Uke tubers, but monosteUc as in the Neotties, not polystelic as in the 

 Ophrydeje. 



Neotti^ Lindl. Gen. and Spec. p. 441 (1835). 



KEY TO SUB-TRIBES 



A. Kostelium none. Pollen-grains single. 



1. Flowers large, erect, conspicuous; lip erect (making them tubular), turned down 



at tip, with yellow crests ; column long, erect; stigma oblong ; poUinia crescent- 

 shaped. Cephalantherinae 



Cephalanthera. 



B. Kostelium present.^ Pollen-grains in tetrads. 



2. Flowers smaUish, horizontal or drooping, inconspicuous ; lip with open nectari- 



ferous cup (hypocliile) and tongue-Uke apex (epichile); column short; stigma 

 oblong; pollinia club-shaped. Epipactinae 



Epipactis. 



' Evanescent (or even absent) in Epipactis leptochila and dunensis. 



