MICROSPERMEiE 289 



power of food and water storage. In place of tubers 

 the leaves may be fleshy, as in Vanilla. 



Orchids are herbaceous. The leaves are entire, 

 with parallel veins, sheathing at the base, scale-like 

 in saprophytes. 



The inflorescence is racemose, or spicate, or the 

 flowers are solitary in the axils of bracts. The 

 flowers are irregular. The perianth is epigynous, 

 superior, in two whorls, irregular, with six segments, 

 three petaloid, two above, one below, the three outer 

 sepaloid, subsimilar. The labellum or posterior petal 

 is generally larger, and used by insects as an alight- 

 ing stage; and by twisting through 180 degrees it 

 assumes an anterior aspect. There are one or two 

 stamens, serving to classify the different types. 

 Most are monandrous. The stamens unite to form 

 a column with the style, or the axis, bearing anthers 

 and stigmas. In monandrous types there is one 

 anther with two stigmas, with a rostellum or third 

 anterior stigma. The anther is opposite the lip, 

 two-celled, and is persistent or falls at length. The 

 pollen is rarely granular, usually aggregated, and 

 united by threads, and in globular masses or pollinia, 

 which are pear-shaped and stalked (with caudicles), 

 ending in an exposed or pouched gland. Possibly 

 there were once three stamens. The single remaining 

 one is anterior. In Orchis two staminodes also 

 occur. In the two-anthered types, such as Cypri- 

 pediunif the anthers are opposite the petals and there 

 is no rostellum, but a simple stigma (of three con- 

 VOL. III. 19 



