Cystopteris. 



FILICES. 



501 



15. CYSTOPTERIS. Bernh. ; J. Smith, I. c. no. 91. bladder-fern. 



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

 Aspidium, Willd. 



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 ; pinnas ovate-lanceolate ; pinnules ovate-lanceolate, deeply pinnatifid ; seg- 

 ments toothed ; rachis winged. — Hook. fl. 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. 

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

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



A very slender fern, 8-12 inches high, smooth, erect. Outline of the frcnd 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 sort of 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 bulbifera, 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, 

 Michx. 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 rachillas, bearing greenish fleshy 

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



