Cystopteris. FILICES. 501 



15. CYSTOPTERIS. Bernh. ; /. Smith, I. c. no. 91. BLADDER-FERN. 



[From the Greek, kyste, a little box, and pteris, a fern,] 



AsPiDiuM, WiUd, 



Sori roundish. Involucre inserted by its broad cucullate base, opening by a broad free 

 extremity which points towards the apex of the segment {Hook.). — Small ferns, with bi- 

 tripinnate fronds of a thin and delicate texture. Veins forked ; the venules free. 



1. Cystopteris fragilis, Bernh. Brittle Bladder-fern. 



Frond bipinnate ; pinnae ovate-lanceolate ; pinnules ovate-lanceolate, deeply pinnatifid ; seg- 

 ments toothed ; rachis winged. — Hook. fi. Bor.-Am. 2. p. 260. Polypodium fragile, Linn, 

 sp. 2. p. 1091. Aspidium fragile, Swartz ; Willd. sp. 5. p. 280; Beck, hot. p. 450. A. 

 lenue, Willd. I. c. ; Pursh,fl. 2. p. 665 ; Torr. compend. p. 382. Nephrodium tenue, Michx. 

 fl. 2. p. 269. Cyathea fragilis, Smith, Engl. bat. t. 1587. 



A very slender fern, 8-12 inches high, smooth, erect. Outline of the frond oblong- 

 lanceolate ; the rachis narrowly winged ; segments 3-5 lines long, about 5-toothed on each 

 margin : teeth rather obtuse, often obscure. Sori mostly solitary at the base of each tooth. 

 Involucre inserted by its broad base at the inside of the sorus, and forming a.sortof cup or 

 hood. 



Crevices of moist rocks : not common. Fr. June - July. The North American plant 

 scarcely differs from the European C, fragilis. 



2. Cystopteris bulbipera, Bernh. Bulb-bearing Bladder-fern. 



Frond bipinnate, lanceolate, the upper part attenuated ; segments oblong, obtuse, serrate, 

 the lower ones pinnatifid ; rachis bulbiferous. — Hook fl. Bor.-Am. 2. p. 260. Polypodium 

 bulbiferum, Linn. sp. 2. p. 1091. Aspidium bulbiferum, Swartz ; Schk. Fil. t. 57, ex 

 Willd. sp. 5. p. 275 ; Torr. compend. p. 382 ; Beck, hot. p. 451. Nephrodium bulbiferum, 

 Mickc. fl. 2. p. 268. 



Frond 1^-2 feet long, slender and graceful, smooth, usually much elongated, and often 

 incurved or flexuous above ; the rachis, and sometimes the rachillee, bearing greenish fleshy 

 ovate compressed bulbs, which are the size of a peppercorn or larger. Pinnie numerous, 

 opposite or alternate : segments 3-5 lines long, rather acutely serrated. Sori very small, 

 solitary, situated near the base of the teeth. Indusium exactly as in the preceding species. 



Shady rocky places : frequent. Fr. July. There can be no doubt of this species being 

 a congener of C. fragilis. The bulbs are sometimes wanting. It is easily known by its 

 very long narrow and tapering frond. 



