Plate 55. 
IS0ETE8 lacustris, Linn . 
Common Quilhvort, 
Gen. Char. Capsules without a ring, indehiscent, immersed in a cavity of 
the very dilated base of long subulate radical leaves :—of two kinds : those 
at the base of the outer leaves containing a few large trigonous spores, 
rough with minute points ( oophoridia ); those at the base of the inner 
ones having numerous, minute, oblong granules ( antheridia ) ; in both the 
contents are seen to be, at least in an early stage, attached to delicate 
slender filaments.— More or less aquatic plants, often submerged. 
Isoetes lacustris; leaves erect or nearly so, stout, subulate, highly cellular; 
base of the rhizome destitute of spiny scales; oophoridia smooth. 
Isoetes lacustris. Linn. Sp. PI. p. 1563. Willd. Sp. PI. v. 5. p. 534. Engl. 
Pot. t. 1084. Bolt. Pil. Brit. p. 74. t. 41. PI. Dan. t. 191. Wahl. PI. 
Lapp. p. 26. Hook. in FI. Lond. v. 4. t. 121. Schk. Pil. t. 172. Sm. 
Engl. FI. v. 4. p. 343. Hook, and Am. Brit. PI. ed. 8. p. 598. Asa 
Gray, Man. Bot. Illustr. p. 606. 
Isoetes Engelmanni. Braun, in Asa Gray, Man. Bot. Illust. p. 605. 
Isoetes riparia. Engelm. in Asa Gray, Man. Bot. Illustr. p. 606. 
Isoetes setacea. Bose, Mem. du Mas. v. 14. t. 6 and 7. 
Isoetes velata. A. Braun, Expl. Alger, t. 37. 
Isoetes Coromandeliarup Linn. Suppl. p. 447. Willd. Sp. PI. v. 5 . p. 535. 
Calamakia folio breviore et crassiore. Dill. Muse. p. 540. t. 80./. 1. 
Dab. Lakes in mountain districts: England, Wales, Scotland, and Ireland. 
This is a very interesting plant, both in structure and in its 
place of growth,—so unlike any other of the Eern-group, whether 
true Perns or which are called Pseudo-Pilices, that some bota¬ 
nists reject them altogether; but, different as the habit of the 
plant may be, the fructifications too much resemble those of Ly - 
cogjodiaceee to allow of their being placed far apart. Presl does 
not admit it among Filices, nor does M. Cosson, in his ex¬ 
cellent ‘ Flore des Environs de Paris.' The present species is 
perhaps much more widely distributed geographically than bo¬ 
tanists in general are aware of; and I cannot but fear that many 
supposed species of authors must merge into this. In the south 
