CLASS DlffiCIA. 201 



mostly bifid, succeeded by a small, 1-celled, 2-valved, 

 many-seeded capsule. The seeds are minute, and 

 furnished with a coma or tuft of down. The willow 

 is the type of the natural order Salicinje, and scarce- 

 ly differs from the Poplar in any thing more than the 

 inferior number of stamina. They are among the 

 earliest flowering shrubs and trees of northern climates, 

 to which they are exclusively confined. Some of the 

 species are alpine, and form the smallest shrubs known. 

 Such is the S. herbacea of the Alps of Europe, which 

 grows also on the summit of the White mountains of 

 New Hampshire. It is a creeping shrub, scarcely 

 ever exceeding 2 inches in height, with smooth, round- 

 ish, veined leaves. One of the most elegant species, 

 remarkable for its pendulous branches, and narrow 

 leaves, is the oriental or Weeping Willow (Salix Baby- 

 lonica). 



One of the most extraordinary plants known is the 

 Vallisneria, a submersed aquatic plant of the natural 

 order Hydrocharideje. It grows in large quantities 

 in the still water of most of the principal rivers near 

 the banks, from Delaware to the Mississippi, and pre- 

 sents partly submerged fields of narrow, linear, 3-nerv- 

 ed, grass-like, olive-green leaves, of a thin and semi- 

 transparent substance, as is usual in all herbage grow- 

 ing under water. From the bosom of some of these 

 arise staminiferous flowers, contained in an ovate, 2- 

 parted spathe. The inclosed spadix is covered with mi- 

 nute flowers, each consisting of a 3-parted calyx, with 2 

 stamens. These, when mature, from the depth at 

 which they are submerged, and the shortness of the 

 peduncle of the spathe, have no other means of attain- 

 ing the surface of the water, but by breaking connex- 

 ion with the parent. As soon as it arises to the surface, 

 the calyx instantly springs open, and the anthers burst, 

 by which impulse, and the accidents of the elemem 



