72 ORCHIDACE.E. 



CLASS II-ENDOGENS OR MONOCOTYLEDONS. 



Stems consisting of woody tissue and cellular tissue (pith) intermixed. Embryo mono- 

 cotyledonous. 



ALJSMACEJE. 



Marsh herbs, with leaves all radical, scape-like flowering sterns, and (in our species) 

 perfect flowers. Sepals and petals each three and distinct. Ovaries 3 to many; dis- 

 tinct, or, at least, separating at maturity, forming 1-2-seeded pods. Stamens from 6 to 

 many; anthers extrorse, 2-celled. Key to genera and species, p. 174. 



ORCHIDACEJE. 



Herbs with irregular 6-merous perianth adnate to the 1-celled ovary; the ovules innu- 

 merable on 3 parietal placentae, becoming fine sawdust-like seeds. One petal, called the 

 lip, is unlike the other two. Stamens consolidated with the style forming the Column. 



This remarkable family of plants is chiefly tropical, one only Calypso borealis 

 reaches the limits of the Arctic Circle. Most of the tropical species are epiphytes. 

 These cling to other plants, usually trees, by means of aerial roots, which, however, 

 take no nourishment from the supporting plants. More than 2,500 kinds of epiphytal 

 orchids are known, mostly South American. These are often remarkable for the beauty 

 as well as oddity of their flowers, characters which make them the most admired of hot- 

 house plants. But the wonderful mechanism of the flowers, by means of which insects 

 effect cross-fertilization, is more interesting to the naturalist than perfume and beauty, 

 which are the more common agents used by higher plants to ensure this aid of insects in 

 the production of good seed. 



The only plant production of this order well known in commerce is vanilla, the fleshy 

 pods of several creeping or climbing species of the genus Vanilla, all natives of Mexico, 

 Colombia and Guiana. Key to genera and species, p. 175. 



:;.*- HABENAB-IA. 



H. maritima, Greene, is more robust than H. elegans, with a short, thick spike of 

 whiter, larger flowers; the lip pure white. 



H. Michaeli, Greene. Still more robust, the fleshy stem bearing many triangular 

 or ovate acute, thin appressed bracts, the spike of greenish flowers 3 inches long; sepals 

 and petals longer, 3 lines long: spur a third longer than the ovary. These two species 

 may be forms of H. elegans. 



H. saccata, Greene. Two or more feet high, with a slender, leafy bracted raceme 

 of green flowers; the side petals falcate, the linear lip much larger than the saccate 

 spur. May be a form of H. gracilis. 



