ANGIOSPERM^E 



397 



Many Orchids are cultivated for their curious or beautiful flowers, but they 

 are of little economic value. Vanilla is the most important member of the order 

 economically. 



Classification. The Orchids are divided into two main sections, the Dian- 

 drse, with two (rarely three) fertile stamens, and the Monandrse, with but one. 

 The Diandne, which are probably the more primitive forms, include the small 

 tropical family, Apostasiese, and the Cypripedilinse, which is represented in the 

 United States by about a dozen species of Cypripedium (" Lady's-slipper," 

 "Moccasin-flower"). C. spectabile, of the eastern United States, is our finest 

 species. 



A 



D 



JDC. 



FIG. 374. A-C, Arethusa bulbosa; t, tuber. B, C, column. D, Habenaria flava. 

 E, C'alopogon pulchellus. F, G, Cypripedium pubescens. G, column; st, sterile 

 stamen. 



The rest of our Orchids, as well as the great bulk of the exotic species, belong 

 to the Monandrse. Some species of Pogonia, Arethusa, Calopogon, and Habe- 

 naria, are among our most beautiful wild flowers. 



Of the exotic genera, cultivated in greenhouses, Cattleya, Lselia, Oncidium, 

 Dendrobium, and Phajus, are among the commonest and most beautiful. 



Burmanniaceae. The Burmanniacese are small plants, many of them sapro- 

 phytes, which, on account of the character of the seeds, are often associated 

 with the Orchids, and supposed to be intermediate between them and the 

 Amaryllidaceae. The stamens, however, are not united with the style. Bur- 

 mannia is represented by two species in the southern Atlantic states. 



BIBLIOGRAPHY 



'98. 1. Bailey, L. H. Lessons with Plants. New York, 1898. 



'01. 2. Cyclopedia of American Horticulture. New York, 1900-1901. 



'87. 3. De Bary, A. Comparative Anatomy. Oxford, 1887. 



