POLVPODIAOEAE (FERK FAMILY) 48 



veins pinnately forking, tlie lowest anterior veinlets bearing the fruit dots near 

 the midvein ; indusium orbicular with a shallow sinus, smooth and naked. 

 (Dryopteris cristata, var. Underw.) — Swampy woods, N. H. to N. C, and westw. 

 to Wise. July. — Rootstock stout, creeping, chaffy (like the stipes) with large 

 bright-brown scales. Appears to hybridize with A. marginale, as does also the 



typii 



'10. A. spinulbsum (0. F. Mtlller) Sw. Stipes with a iew pale-bi'own deciduous 

 scales ; frond ovate-lanceolate, twice pinnate ; jiinnae oblique to the rhachis, 

 elongated-triangular, the lower pairs broadly triangular ; pinnules set obliquely 

 on the midribs, connected by a very narrow wing, oblong, acute, incisely serrate 

 or pinnatifid with spinulose-toothed lobes ; indusium smooth and without mar- 

 ginal glands. {Nephrodium Strempel ; Dryoptens Kuntze.) — Rich woods, 

 Nfd. to Va., Ky., and northwestw. (Greenl., Eu.) A. pittsfokdense (Slos- 

 son) Eastman, a supposed hybrid with A. marginale, occurs in Vt. and on Staten 

 I., N. Y. 



Var. intermddium (Muhl.) D. C. Eaton. Scales of the stipe few, brown with 

 a darker center; frond broadly oblong-ovate, tripinnatifid ; pinnae spreading, 

 oblong-lanceolate, the lower unequally triangular-ovate ; pinnules crowded, 

 ovate-oblong, spreading, pinnately cleft ; the oblong lobes spinulose-toothed at 

 the apex ; margin of the indusium denticulate and beset with minute stalked 

 glands. {Nephrodium spinulosum, var. Davenp. ; Dryoptens spinulosa, var. 

 Underw.) — Woods, common. 



Var. dilatlltum (Hoftm.) Hook. Scales of the stipe large, brown with a dark 

 center ; frond broader, ovate or triangular-ovate in outline, tripinnatifid; pin- 

 nules lance-oblong, the lowest often much elongated ; indusium glandular- 

 ciliolate. (Nephrodium spinulosum, var. fructuosum Gilbert). — N. S. to Va., 

 and N. Y. (Eu.) Forma anadenium Robinson is in all respects like var. dila- 

 tatum, but with the indusium destitute of glands (the var. dilatatum of Am. 

 auth. chiefly, not Hook.) — Common, chiefly in rocky upland woods. (Asia.) 



Yar. concordlElnum (Davenp.) Eastman. Fronds tripinnate; pinnules (of 

 the 3d order) small (4 mm. long), elliptical, spinulose-denticulate ; indusium 

 glandular-puberiilent. — Concord, Mass. {Purdie). 



18. CYST6PTERIS Bernh. Bladder Fern 



Fruit dots roundish, borne on the back of a straight fork of the free veins ; 

 the delicate indusium hood-like or arched, attached by a broad base on the inner 

 side (toward the midrib) partly under the fruit dot, early opening free at the 

 other "side, which looks toward the apex of the lobe, and is somewhat jagged, 

 soon thrown back or withering away. — Delicate ferns with 2-3-pinnate fronds ; 

 the lobes out-toothed. (Name composed of Kiia-Ti.9, a bladder, and irrfpis, fern, 

 from the inflated indusium.) 



1. C. bulbifera (L.) Bernh. Frond lanceolate, elongated, attenuate (3-6 

 dm. long), 2-pinnate ; the pinnae lanceolate-oblong, pointed, horizontal; the 

 rhachis and pinnae often bearing bulblets underneath, wingless; pinnules 

 crowded, oblong, obtuse, toothed or pinnatifid; indusium short, truncate on 

 the free side. {Filix Underw.) — Shaded ravines, chiefly on calcareous rocks. 

 July. 



2. C. frigilis (L.) Bernh. Frond oblong-lanceolate (1-3 dm. long, besides 

 the brittle stalk which is fully as long), 2-3-pinnate; the pinnae and pinnules 

 ovate or lanceolate in outline, irregularly pinnatifid or cut-toothed, mostly 

 acute, decurrent on the mnrgined or winged rhachis; indusium tapering or 

 acute at the free end. {Filix Underw.) —Shaded cliffs, rocky woods, etc.; 

 common and varying greatly in the shape and cutting of the pinnules. July. 

 (Cosmop.) 



16. W06DSIA R. Br. 



Fruit dots round, borne on the back of simply forked free veins ; the very thin 

 and often evanescent indusium attached by its base all around the receptacle, 

 under the sporangia, either small and open, or else early bursting at the top into 



