Order 138.— THE ORCHIDS. 



veined, entire, on long petioles. Scape l-2f. liigli, branching in whorls, bearir;g nu- 

 merous purplisli-whitc flowers, in •Tuly. 



2. SAGITTATJA. Arrow-head. 



Flowers monoscious, rarely dioecious, tlie $ with about 24 stamens, 

 the $ with numerous ovaries crowded in a head, and becoming in fruit as 

 many compressed, margined achenia. — U Stemless plants, leaves radical, 

 generally arrow-shaped. Flowers in whorls of 3's, the sterile ones above 

 the fertile. 



S. variab''ili3. A curious plant, conspicuous with its large white flowers among the 

 rushes and sedges of sluggish waters. The petals are wholly white, and the 

 scape simple, with the stalks 1-flowered. The leaves are generally arrow- 

 shaped (as seen in the figure), but exceedingly variable, sometimes lanceolate, 

 and sometimes even consisting of a petiole only. About If. high. Jul^. 



Order CXXXYIII. ORCHIDACE.E. The Orchids. 



Herhs perennial, with thick, fleshy roots; entire, parallel-veined leaves ; 

 ■flowers very irregular, but ^^ 'perianth consisting always of 6 parts, viz., of 3 

 sepals and 3 petals^ all usually colored, the lower petal called the 

 lip differing in form from the others, and frequently spurred at base ; 

 stamens 3, but only 1 or rarely 2 of them perfect, united with the 

 style and forming what is called the column ; anthers 2, 4 or 8-celled; 

 'pollen powdery, or waxy, or granulated ; oiarxj 1-celled, many-seeded. 



Analysis of the Genera. 



* Stems green, furnished with one or more leaves 2 



* Stems green, furnished with sheaths instead of leaves.... 



* Stems brownish, furnished with sheaths and no leaves, or a late one. . . .0 



2 Corolla lip very large, inflated and sack-like. . ..a 



2 Corolla lip of various forms, but neither very large nor sack-like. . . .8 



3 Corolla produced into a spur behind . . . .b 



8 Corolla destitute of a spur 4 



4 Flowers small, many, in a loose raceme, beardless. . . .e 



4 Flowers small, many, in a close, twisted spike, beardless. .. .f 



4 Flowers showy, purple or yellow, few or 1 only g 



a Root fibrous. Lip obtuse, spurless. Anthers 2. Ladi/^s-slipper. CvrniPK'DiUM. 1 



a Koot a corni. T/ip S-lobcd, 2-spurrod. Anther 1. Cab/pso. Cm.yp'so. 



