190 PLANTS OF MASSACHUSETTS. 



ORDER 231. HYDROCHARIDE^E. Frog-bit Tribe. 



Sepals 3 ; petals 3 ; ovary single and inferior, 1-celled or many ; 

 fruit not opening by valves ; flowers spathe-like, monoclinous or 

 diclinous ; plants floating, or submerged ; leaves with parallel 

 veins. 



The plants of this order are spread widely over the world, 

 though only a few are found in New England ; Hydrocharis, from 

 which the order is named, is unknown here. 



Udora. Nuttall. 19. 9. 

 Has 9 stamens, 3 interior ; tube of the perianth long ; capsule 

 bladder-like ; about 3-seeded. 



U. Canadensis. Nutt. Ditch Moss. In waters, submerged, 

 and stem much-divided, with whorled leaves, and small white ax- 

 illary flowers ; August. This is Serpicula verticiUata, Muhl. 



Vallisneria. L. 20. 2. 

 Has an ovate, 2-parted spathe, and a spadix of minute flowers ; 

 perianth 3-parted ; stamens 2 ; scape long and spiral ; stigmas 3, 

 sessile ; capsule long, cylindrical, 1-celled, and many-seeded. 

 Still waters. 



V. spiralis. L. Tape Grass. The sterile or staminate 

 flowers grow on short scapes at the bottom of the water ; the fer- 

 tile or pistillate flowers are on a long spiral stem or scape rising 

 to the surface ; leaves very long, linear, obtuse, 3-nerved, radical, 

 about 3 lines broad. 



This was considered by Michaux a distinct plant from that of 

 Europe, and named by him V. Americana ; it seems to be a mere 

 variety, and is thus named by Nuttall, Torrey, &c. 



This plant exhibits a beautiful provision for the fecundation of 

 the embryo seed. The spiral stem untwists so as to keep the 

 pistillate flower at the surface, and exposed to light, and heat, and 

 air ; and, when the flower is in its perfect state, the staminate 

 flowers, by a natural process, break away from the root at the 



