330 CRYPTOGAMIA— FILICES. Isoetes. 

 480. ISOETES. QuiU-wort. 



Linn. Gen. 561, It. Scan. 420./. 419. Juss. 17. Fl. Br. 1 144. 



Lam. t. 862. Spreng. Crypt./. 41. 

 Calamaria. DHL Muse. 540. t. 80. 



Nut. Ord. Filices. Linn. 55. Juss. 5. Marsileacea . Br. 

 Prodr. 166. 



Barr. Fl. at the inside of the base of the inner yronr/s. Cow- 

 7Mo/i receptacle membranous, sessile, ovate, somewhat 

 compressed, of 1 cell. /Itithers? or Pollen P of numerous 

 oval grains, each, according to Dr. Hooker, pellucid in 

 the centre. 



Fert. Fl. similarly situated, at the bases of the outer Ji'Otids. 

 Common rccept. as in the barr.Jl., not bursting, of 1 cell, 

 with several transverse bristle-shaped bars. Seeds very 

 numerous, combined 8 together, in little stalked globules, 

 externally rough ; each angular at the inner side, convex 

 at the outer. 



By analogy only do we thus venture to name the parts of 

 Jructification ; nor has the germination of this curious 

 genus, still less its impregnation, ever been verified. The 

 very few species known are aquatics, growing, and per- 

 fecting seed, entirely under water, at the bottoms of lakes 

 or ponds, in Europe or in the East Indies. The roots 

 are perennial, tuberous, with many long, stout, hairy 

 Jihres. Fronds radical, tufted, simple, awl-shaped, nearly 

 upright, monoecious, bearing the fructification at their 

 base, close to the root. Mr. Sowerby thought he found 

 two cells in the common receptacles^ as delineated in Fngl. 

 Bot. Dr. Hooker observed but one, though his figure, 

 which is excellent, shows what may account for the mis- 

 take, and it is not im})ossible that the partition oixhefridt, 

 to which perhaps the seeds are originally attached, may 

 subsequently be obliterated. The whole matter merits 

 further inquiry, the impregnation of submersed plants in 

 general, especially with separated flowers, being very little 

 understood. 



1. \. lacustris. Europaean Quillwort. Merlin's Grass. 

 Fronds bluntly quadrangular, with four longitudinal cells. 



I. lacustris. Linn. Sp. PI. 1563. mild. v. 5. 534. Fl. Br. 1 144. 



Engl. Bot.v.\6.t. \034. Hook. Scot.p. 2. 160. Lo7ul.t.l3l. 



Boll. Fit. 74. ^ 4 1 . Fl. Dan. t. 191. 

 Calamaria folio bievioie et crassiore. Dill. Muse. 540. /. 80,/. 1. 



