Sept.] FLOWER-GARDEN. 505 
The Vallisneria Americana. 
Some account of the Vallisneria jimericana, may not prove unaccep- 
table to the curious, the more especially as it tends to cast some 
light on the " loves" and sexes of plants. 
This extraordinary vegetable production grows in the river Dela- 
ware not far from Philadelphia, and may, with care, be introduced 
by means of seeds or roots, into rivers, ponds, and canals. Sec. 
Another species, the S/iiralis, is found in the East Indies, in Norway, 
and various parts of Italy. The American species, flowers gene- 
rally in the latter pan of August or in September. 
The Vallianeria belongs to the Class Dioecioj and Order Diandriay 
bearing male and female flowers on separate plants. The female 
plant produces long, tubular, purple flowers, which stand singly on 
the top of a stalk, curiously twisted in the form of a screw, which is 
common to both sfiecies; 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 fired with love, they 
burst open the Spatha in which they are contained, detach them- 
selves from the Receptacle to which they are fixed, and rise up to 
the surface 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 eff'ected, it is difficult 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 eaiiy 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 certainly be determined. 
The hint of there being diff'erent 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 female dust be carried along by the wind, and dis- 
persed upon the female, the same eff'ect will follow, as if a branch 
of the male had been suspended over it." 
3S 
