SEPT.] FLOWER-GARDEN. 497 



The Vallisneria americana. 



Some account of the Vallisneria americana, may not prove unaccep- 

 table to the curious, the more especially at 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, 8cc. 

 Another species, the sfiiralis, is found in the East Indies, in Norway, 

 and various parts of Italy. The American species, flowers gene- 

 rally 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 on 

 the top of a stalk, curiously twisted in the form of a screw, which is 

 common to both s/iecies ; 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 flow- 

 ers growing near them, or scattered thereon, impregnates the 

 seeds contained within the Germen. 



The Pollen being discharded on the Stigma, the embryo seeds are 

 impregnated ; but how this impregnation is effected, 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 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 

 perhaps what never will with certainly 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) flowtrs 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." 



3s 



