493 • FERN FAMILY. 



17. CYSTOPTERIS. (Greek for bladder fern, alluding to the thin, 

 sometimes inflated indusium.) Species few, mostly northern. 



C. frdgilis, Hernli. Shaded or moist, rocky places, common N. ; fronds 

 very delicate, 4'-8' long, with slender stalks, oblong-ovate, twice-pinnate ; 

 pinme with a narrowly margined rhachis ; pinnules oblong or ovate, 

 toothed or incised, very variable ; indusium pointed at the upper end. 



C. bulbifera, Bernh. Wet places, oftenest in ravines, from N. Car., 

 N. ; fronds I'-'-S'^ high, o'-5' wide at the base, narrowed above and much 

 elongated, twice pimiate, bearing scattered bulblets beneath ; pinnules 

 oblong, obtuse, toothed or pinnatifid ; indusium roundish, truncate on 

 the upper side. 



18. NEPHROLEPIS. (Greek: kidney, scale, referring to the shape 

 of the indusium.) 



N. exaltata, Schott. Fia. and the tropics, and one of the commonest 

 ferns of conservatories ; fronds l°-6° long and very narrow ; the pinn* 

 crowded, lanceolate, entire or slightly crenulate, the upper side auricled 

 at the base ; indusium kidney-shaped. 



N. da\/allio)des, Kunze. Popular conservatory fern from E. Indies, 

 with a stoloniferous base ; and pinnate fronds 2'^-4° long and 1° broad, 

 on rather short, strong stipes ; pinnas 4'-6' long and i'-l' broad, lanceo- 

 late, the lower ones opposite and sterile and serrate, the upper ones fer- 

 tile and longer and narrower, more deeply toothed. A common form is 

 var. FURCANS, in which the ends of the upper pinnte, and often of the 

 frond itself, are deeply 2-ao -forked. 



19. WOODSIA. (For Joseph Woods, an English botanist.) Several 

 species occur in our limits, the following being the commonest. 



"W. obtiisa. Torr. Rocky places, from Car., N. ; fronds 0'-18' high, 

 slightly glandular, broadly lanceolate, pinnate, with ovate or oblong, deeply 

 pinnatifid or again pinnate divisions ; lobes oblong, obtuse ; indusium at 

 first closed, opening into a few ragged lobes. 



W. Ilv^nsis, R.Br. Exposed rocks, common N., and along the Alle- 

 ghanies ; forms large tufts ; fronds 4'-8' high, rusty chaffy beneath, 

 oblong-lanceolate, pinnate; divisions ovate, obtusely ^lobed ; indusium 

 obscure, consisting of a few jointed hairs. 



20. ONOCLEA (including STRUTHIOPTERIS), SENSITIVE FERN. 



(Name, from the Greek, meaning a closed vessel, referring to the berry- 

 like fructification.) 



O. sensibilis, Linn. Brake. Common in wet places, and often a 

 weed in hilly pastures ; sterile fronds of all sizes up to 2° high, broadly 

 triangular-ovate, the rhacliis winged ; pinn;e not many, lanceolate, entire, 

 or obtusely lobed less than half way to the midrib, veins everywhere re- 

 ticulated ; fertile fronds with few, closely appressed pinnas. 



O. Struthi6pteris, Hoffm. Ostrich Fern. Alluvial grounds, N. ; 

 sterile fronds tall, 2°-'j° high, lanceolate, narrowed at the base into a 

 short, angular stalk, pinnate ; pinnaj very many, narrowly lanceolate, 

 pinnatifid more than half way to the midrib ; lobes numerous, oblong ; 

 fertile fronds very much shorter, blackish, standing erect after the others 

 have withered. 



21. DAVALLIA. (Named for M. Davall, a Swiss botanist.) Many 

 tropical or sub-tropical species, many cult, in conservatories. 



D. Canariensis, Smith. Hare's-foot Fern. Canaiy Islands, etc. ; 

 rootstock creeping above ground, covered with brownish scales, and 



