CRYPTOGAMIA— FILICES. Isoetes. 343 



480. ISOETES. Quill-wort. 



Linn. Gen. 561. It. Scan. 420./. 4 19. Juss. 17. Fl. Br. 1 144. 

 Lam. t.862. Spreug. Crypt, f. 4 1 . 



Calamaria. Dill. Muse. oAO. t.SO. 



Nat. Orel. Filiccs, Linn, 55. Juss. 5. Marsileacece. Br. 

 Prodr. 166. 



Barr. Fl. al the inside of the base of the mner fronds. Com- 

 mon receptacle membranous, sessile, ovate, somewhat 

 compresseil, of 1 cell. Anthers? or Pollen F of numerous 

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

 the centre. 



Fert. Fl. similarly situated, at the bases of the outer Jronds. 

 Common recept. as in the barr.Ji.^ not bursting, of 1 cell, 

 with several transverse bristle-shaped bars. Seeds very 

 numerous, combined 3 together, in little stalked globules, 

 externallv rouffh ; each aiWular at the inner side, convex 

 at the outer. 



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

 fructification; nor has the germination of this curious 

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

 very tew 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 

 fbres. Fronds radical, tufted, simple, awlshaped, nearly 

 upright, monoecious, bearing the fructification at their 

 base, close to the roof. Mr. 8owerby thought he found 

 two cells in the conmion receptacles, as delineated in Engl. 

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

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

 take, and it is not impossible that the partition of the /////V, 

 to which perhaps the seeds are originally attached, may 

 subsequently be obliterated. The whole matter merits 

 further in((iiiry, the impregnation of submersed plants in 

 general, espccudly with separated flowers, being very litUe 

 understood. 



1. l.lacustris. EuroparanQuillwort. Merlin's Grass. 

 Fronds bluntly quadrangular, wilh four longitudinal cells. 

 I. lacustris. Lwn. Sp, />/. l.-,(.S. trUl,!. r.:>.:>:\\. I'l. Ur. 11 14- 



En^L Hot. V. Hi. /. lUS 1. Hook. Scot. p.'l. I C'O. Loud. t. LSI. 



Bull. Fil.7\. t.W. ri.Dun.t. \[)\. 

 Calamaria folio hrcviorc et crassiorc. Dili Muse. 5-10. /.SO./. 1 . 



