596 FILICES. (FERNS.) 



obtuse, crenatcly pinna tifid-toothed, with a single smooth fruit-dot just below 

 the sinus between each rounded minutely-toothed lol>c. (W. Perriniana, Hook. 

 if Grev. Aspidium obtusum, Willd.) Rocky banks and cliffs; common, es- 

 pecially westward. July. 



$2. WOOD SI A PROPER. Indusium minute or evanescent, open and flattened 

 from an early stage and concealed under the fruit-dot, except the fringe of bristly- 

 chaffy hairs into which its margin is dissected. 



2. W. IlveilSiS, R. Brown. Frond oblong-lanceolate (2' -4' long by 1' 

 wide), smoothish and green above, thickly clothed underneath as well as the stalk 

 with rusty Iristle-like chaff, pinnate ; the pinna3 crowded, oblong, obtuse, sessile, 

 pinnately parted, the numerous crowded pinnules oblong, obtuse, obscurely crcuate, 

 almost coriaceous, the fruit-dots near the margin, somewhat confluent when old. 

 (Nephrodium rufidulum, Michx.) Exposed rocks, common, especially north- 

 ward, and southward in the Alleghanies. June. (Eu ) 



3. W. glabcllcl, R. Brown. Smooth and naked throughout ; frond linear 

 (2' -5' high), pinnate ; pinnce rather remote towards the short stalk, rhombic-ovate, 

 very obtuse (2" -4" long), cut into 3-7 rounded or soineichat wedge-shaped lobes. 

 Kocks, Little Falls, New York ( Vasey) ; Willoughby Mountain, Vermont ( Wood, 

 C. C. Frost) ; and high northward. 



13. CYSTOPTERIS, Bernhardi. BLADDER-FERN. (Tab. 12.) 



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 (towards 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. Tufted Ferns with slender and deli- 

 cate 2-3-pinnate fronds; the lobes cut-toothed. (Name composed of KVO-TIS, 

 a bladder, and Trrtrpi's, Fern, from the inflated indusium.) 



1. C. bulbifcra, Bcmh. Frond lanceolate, elongated (l-2 long), 2- 

 pinnate; the pinna; lance-oblong, pointed, horizontal (l'-2'long); the rhachis 

 and pinna; often bearing bulblets underneath, wingless ; pinnules crowded, oblong, 

 obtuse, toothed or pinnatifid ; indusium short, truncate on the free side. (As- 

 pidium bulbifcrum, Swartz. A. atomarium, MuhL!) Shaded, moist rocks; 

 common. July. 



2. C. frugilis, Bernli. Frond oblong-lanceolate (4' -8' long, besides the 

 stalk which is fully as long), 2 -3-pinnate; the pinna; and pinnules ovate or lan- 

 ceolate in outline, irregularly pinnatifid or cut-toothed, mostly acute, dccurreni 

 on the margined or winged rhachis; indusium tapering or acute at the free end. 

 Var. DENTATA, Hook, is narrower and .less divided, barely twice pinnate, with 

 ovate obtuse and bluntly-toothed pinnule;. (Aspidium tenue, Swartz.) Shaded 

 clift's ; common : very variable. July. (Eu.) 



14. ASPIDIUM, Swartz. SHIELD-FERN. WOOD-FERN. (Tab. 12.) 



Fruit-dots round or roundish, borne on the back or sometimes on the ex- 

 tremity of (in our species) pinnate and free veins, scattered, or sometimes 



