ORDER HYDROCHARIDEJE, OR FROG-BIT TRIBE. 50 tf 



in many ditches and ponds in this country ; it has long stems 

 which float on the water, sending down roots at intervals below, 

 and erecting its leaves and flower-stems a little above the sur- 

 face. The veins of the leaves run nearly parallel from the foot- 

 stalk to the apex, and are united by little cross bars. The 

 staminiferous and pistilliferous flowers are here distinct; the 

 former are sometimes called barren flowers in botanical works, 

 because they do not bear seeds, whilst the latter are spoken of 

 as infertile flowers. This is an incorrect application of terms, 

 since the pistilliferous flowers can no more produce seed without 

 the pollen of the staminiferous, than the latter can without the 

 ovules of the former. In both kinds of flowers, we find a calyx 

 of three sepals, surrounding a corolla with three petals. In the 

 Frog-bit there are nine stamens, disposed in three rows, on the 

 one flower ; and within these, three imperfect styles ; but in 

 other species, the number of stamens is indefinite. The other 

 flower is destitute of stamens, and has an inferior ovarium, 

 consisting of six adherent carpels, with separate styles and 

 stigmas, each carpel containing numerous ovules. In some 

 the order, the partitions dividing the seed-vessel give way, so 

 that the ovarium contains but a single cell. 



686. The Stratiotes, which has been so named from its sword- 

 shaped leaves and its fancied military appearance, is a very orna- 

 mental aquatic. It remains submerged during the greater part 

 of the year, but raises itself to the surface on special stalks during 

 the flowering season, by means of which contrivance the pollen 

 may be scattered upon the stigmata. A still more curious means 

 of effecting this object is met with, however, in another plant of 

 the order, the Vallisneria. This plant, unlike the two already 

 named, which prefer still waters, grows in rivers and rapid 

 streams, of which the level is undergoing frequent and consider- 

 able variations. Now it is essential to the well-being of the 

 plant, both in regard to the fertilisation of the seed and the 

 ripening of the ovule, that the pistilline flowers, from the time 

 of their expansion, should be kept on the surface of the water, 

 and secured from frequent submersion. This is effected by a 



