71 



diandrous and monandrous forms of this column were described 

 and illustrated with lantern slides, as were the other features of 

 the family. The two kinds of pollinia were explained, that which 

 develops appendages at the base, and that which is without 

 appendages, or develops them at the apex, the former associated 

 with the persistent anthers, the latter with the deciduous anther. 

 Attention was called to the thickened stems of most orchids. In 

 some the stem is very short and much enlarged. Such stems 

 are known as psetidobidbs. Oncidhun and Odontoglossinn are 

 examples of this sort. In others the entire stem is thickened, as 

 is the case in Cattleya and Dendrobhim. The lateral and terminal 

 forms of inflorescence were described, the former arising from the 

 base of the pseudobulb, the latter from the apex. The vernation 

 of the leaves, whether convolute or conduplicate, was illustrated. 

 The manner of growth, whether limited or unlimited, was indi- 

 cated : the limited in such genera as Epideiidron, Oncidiinn, 

 Odontoglossuvi, Masdevallia, and in fact the greater part of the 

 orchids ; the other, the unlimited, in such genera as Vaidlla and 

 Angraccuvi, in which the axis ascends continuously. 



The latest comprehensive treatment of this interesting family is 

 by Pfitzer, in Engler and Prantl's Nati'irlicJien Pflaiizenfamdien. 

 In his classification he utilized the characters and habits of growth 

 referred to above. 



The orchid family is a large one, embracing some 6,000 or 

 7,000 species, mostly distributed in tropical regions. Compara- 

 tively few are found in the warm temperate, and almost none in 

 the cold portions of the temperate zone. The center of their dis- 

 tribution in the Old World is in India and the Malay region, 

 such genera as Dendrobiinn, Vanda, and Bidbophylhnn represent- 

 ing them in that region. In the New World they are found in 

 the greatest numbers in Brazil and northern South America. 

 Such genera as Cattleya, Laelia, and Masdevallia illustrate these. 

 In the United States there are about 150 species, representirg 44 

 genera. These are mainly terrestrial, the comparatively few 

 epiphytes being confined to Florida and the Gulf States. 



By far the greater part of the orchids grow in hot humid 

 regions, where they are found most exclusively growing on trees, 



