XYRIDEiE. 191 



bottom of the water, and rising to the surface float about so that 

 the pollen is thrown upon the stigma of the fruit-bearing flower. 

 After this process, the seed is matured under the water. The 

 ease and rapidity with which the spiral stem unwinds and extends 

 itself, has been often remarked in the rapid rise of the waters of 

 the River Rhone, being some " feet in a few hours," and yet the 

 flower preserved its position at the surface. Darwin. 



ORDER 232. COMMELINEiE. Spider-Wort Tribe. 



Sepals 3, leaf-like ; petals 3, colored, sometimes cohering at 

 the base ; stamens 6 or less, inferior ; ovarium 3-celled ; style 1 ; 

 capsule 2 or 3-celled, and 2 or 3-valved ; leaves commonly 

 sheathing at the base. 



The genus Commelina, which gives name to the order, seems 

 not to be found in New England, though it is common in the ad- 

 joining State of New York. 



Tradescantia. L. 6. 1. Spider Wort. 



In honor of J. Tradescant, gardener to Charles the First. A 

 few species are cultivated, though none are very beautiful ; spe- 

 cies belong chiefly to tropical America and India. 



T. Virginica. L. Introduced from the Middle States, is 

 found in our gardens ; rather handsome. The flowers contain 

 fine jointed hairs. 



ORDER 233. XYRIDE.E. 



Sepals 3, glume, or chaff-like ; corolla 3-petalled, and the fertile 

 stamens standing on the claws of the petals, while the sterile sta- 

 mens alternate with the petals ; ovary single, capsule 1 -celled, 

 3-valved, many-seeded ; flowers in naked and terminal heads ; 

 leaves radical and ensiform. Grow chiefly within the tropics ; a 

 few in the United States. 



