The Guiana Orchids. 573 



a hard stalk, the flowers are produced at the apex, and 

 the aerial roots extend in every dire6lion without mat- 

 ting together. 



In these two great divisions we have the germ of a 

 natural classification which nearly corresponds with the 

 tribes Epidendrese and Vandeae, the first having usually 

 terminal and the second lateral inflorescence. Botanists 

 separate these and the other tribes to be presently men- 

 tioned, by certain chara6lers conne6ted with the anthers 

 and pollen masses, but as these are not conspicuous or 

 easily recognisable by any one but the student we have 

 looked round for something less difficult. To recapitulate 

 therefore, before going farther, the Epidendreas were 

 originally rock plants and have terminal flowers and 

 generally stalked pseudo-bulbs or fleshy stems, while 

 the Vandeae were sand-orchids and have flowers coming 

 from below the bulbs, or where these are absent, from 

 among the leaves at their base. There are a few excep- 

 tions, but not enough to invalidate the rule. 



The third tribe, Neottieae, is not so easily recognised as 

 the two first, in fa6l it is rather anomalous, containing 

 such genera as Vanilla and Sobralia as well as others 

 more stri6tly terrestrial. The fourth and fifth tribes, 

 Ophrydeae and Cypripedeae, are wholly terrestrial, being 

 represented in Guiana by only one genus each. 



The following list of the genera found in Guiana will 

 show how they are arranged in tribes: — 



Tribe i. — Epidendrece (epiphytal ; growing on rocks or trees.) 

 Pleurothallis, Stelis, Masdevallia, Oftomeria, Liparis, Bulbophyllum, 

 EUeanthus, Bletia, Diothonea, Scaphyglottis, Diacrium, Isochilus, 

 Epidendrum, Cattleya, Laelia, Brassavola, Schomburgkia. 



Tribe 2. — Vandece (epiphytal ; growing en sand or trees. J 

 Galeandra, E'olystachya, Cyrtopodium, Zygopetalum, Aganisia, Aca- 



