UJM3A. DIANDRIA. MONOGYNIA. Si 



duced, which is again, and often repeatedly, proliferous. Floivers 

 not seen. Root a single fibre, proceeding from the middle of 

 the under surface of the frond, terminated at the extremity by 

 a sheath-like appendage, resembling the calyptra of mosses. 

 Hab. In pure stagnant waters. Deeifield, Massachusetts. Dr, 

 Coo ley and Mr. Hitchcock. At Saratoga Springs, New- 

 York. Dewey. Pennsylvania. Muhlenberg. 



2. L. minor L. : fronds nearly ovate, compressed ; roots 

 solitary. H o o A;. 1. c. p. 1 1. W ill d. Spec, IV. p. 194. 

 Mick. FLU. p.\63. Muhl, Cat.p.ne. PurshFl.], 

 p. 22. Eng. Bot, t. 1095. G r o n. Virg. p. 143. Rotm^ 

 ^ Schult. I. p. 283. 



Fronds a line, or a line and a half long, thick and succulent^ 

 slightly convex beneath, multiplying prodigiously by gemmae ; 

 the young closely sessile, giving the plant a stellated appear- 

 ance. Flowera not seen. 



Hab. In stagnant waters : very common throughout the United 

 States. 



3. L. gibba L.: fronds obovate, nearly plane above, he- 

 mispherical beneath; roots solitary. Hook. I. c. p. 11, 

 wind. Spec, IV. p. 194. Pursh fl. I. p. 22. Eng. 

 Bot. t. 1233. Roenu ^ Schult. I. p. 283. 



Fronds the size of L. minor, but distinguished by the gibbous, 



pellucid, reticulated under surface. Ho o k. 

 Hab. In stagnant waters near Liverpool, in the western parts of 



the State of New-York. (c. fl.) Pursh. 



4. L. polyrrhiza L.: fronds obovate-rotundate, com- 

 pressed ; roots numerous, fasciculate. Hook. I.e. Wiild. 

 Spec. IV. p. 195. Pursh Fl. 1. p. 22. Eng. Bot. 2458. 

 Roem. <^ Schult. I. p. 283. 



Fronds 3 — 4 lines in length, succulent, and of a firm texture ; a 

 little convex beneath, sparingly producing gemmae. Hoot a 

 bundle of 8 or 10 simple fibres proceeding from the middle of 

 the frond. Flowers not seen. 



Hab. In stagnant waters ; frequently in company with L. minorf 

 but not so common. 



A very singular genus, which was not accurately defined by 

 any author until it was lately illustrated by Hooker. This 

 deservedly celebrated botanist, to whom we are so largely in- 

 debted, more particularly for his labours in the Cryptogamia, 

 has given a new description of the genus Lemna in his valuable 

 Flora Scotica, which I shall here quote. " All the species are 

 aquatics, floating on the surface, or sinking only when the seed 

 is ripe, and the plant dying away. Fronds (for I cannot consider 

 the whole plant, from which spring the flowers, as a leaf) mi- 

 nute, ovate or orbicular, compressed, foliaceous, or thick and 

 succulent; from the centre beneath, throwing out one or more 

 slender roots, which are terminated by sheath-like appendages 



