16 DIOECIA 



ORDER 2. 



VALLISNERIA. This is an aquatic plant of 

 diandria which there are two species: it grows in great quan- 

 Twostamina. tities in Italy, in the canal and ditches in the neigh- 

 bourhood of Pisa, and also in the Rhone. Its natu- 

 ral habits are highly curious and interesting. The 

 flowers which bear Stamina are produced at the bot- 

 tom of the water till they come to maturity, but with- 

 out expanding; they then separate from the footstalks 

 on which they are borne, and rising to the top, open 

 suddenly with an elastic force, and in this state swim 

 at large on the surface. The other plant producing 

 the Pistilla, bears its flowers on a spiral stem, which 

 at the same season, has the power of uncoiling ac- 

 cording to the depth of the water, so as to arrive at 

 the surface at the same time, and thus receive the 

 Pollen from the Antherae of the floating Stamina. 

 The flowering season being past, the spiral stem then 

 contracts and completes its fructification at the bottom : 

 the other flowers with Stamina, are dispersed and 

 perish. 



The plant with staminiferous blossoms is marked 

 N°l. the other, which only produces Pistilla, and con- 

 sequently the seed, is marked N" 2. 



The flowers producing Stamina are white, those 

 producing the Pistilla are purple. 



