506 THE PLEASURE GARDEN. [Sept. 
way, and various parts of Italy. The American species flowers 
generally in the latter part of August or in September. 
The Vallisneria belongs to the class Dioecia, and order Diandria, 
bearing male and female flowers on separate plants. The female 
plant produces long, tubular, purple flowers, which stand singly oa 
the top of a stalk, curiously twisted in the form of a screw, which 
is common to both species', when the flowers are about to expand, 
this screw or spiral stalk relaxes more or less according to the depth 
of the water, and suffers the flowers to rise up to the surface, where 
they float in expectation of a visit from their husbands. 
The flowers of the male plant are very numerous, small, and of 
a white colour; they are contained within a spatha or sheath, which, 
stands on a short foot-stalk that never rises to the top of the water; 
the flowers being arrived at maturity and tired with love, they burst 
open the spatha in which they are contained, detach themselves 
from the receptacle to which they are fixed, and rise up to the sur- 
face of the water, where they float about as if in search of their 
mates, and suddenly, with a kind of elasticity, open themselves and 
discharge their pollen, which being conveyed to the female flowers 
growing near them, or scattered thereon, impregnates the seeds 
contained within the germen. 
The pollen being discharged on the stigma, the embryo seeds are 
impregnated, but how this impregnation is effected it is difl^icult to 
say; indeed, while the affair of impregnation in animals is involved 
in so much obscurity, we can scarcely expect to discover more of 
it in vegetables. 
It has been the opinion of some of the early writers on the sexes 
of plants, that the pollen in substance passed through the style, and 
so impregnated the seeds in the ovary; but this is a very irrational 
supposition, for it is not probable that the pollen, which is nothing 
more than a case for the true sperm, should pass through a part 
which has every appearance of being impervious to it. 
Whether the sperm itself be conveyed through the style is per- 
haps what never will with certainty be determined. 
The hint of there being different sexes in plants seems first to 
have been taken from the Dioecia class, or such as produce (male) 
flowers with stamina on one plant, and (female) flowers with pis- 
tilla on another. 
"If the dust of the branch of a male palm tree, (says Aristotle,) 
be suspended over the female, the fruit of the latter will quickly 
ripen; and if the male dust be carried along by the wind and dis- 
persed upon the female, the same effect will follow as if a branch 
of the male had been suspended over it." 
"Naturalists, (says Pliny,) admit of distinction of sex not only 
in trees but in herbs and all plants; yet this is no -where more ob- 
servable than in palms, the females of which never propagate but 
when they are fecundated by the dust of the male." 
JVote. Those who wish to become scientifically acquainted with 
the Linnsean, or sexual system of plants, will be greatly edified by 
consulting that very valuable work, the "Elements of Botany," 
