A. cristatiun, Swartz. Wet places in woods, frequent; fronds nai- 

 rowly (iblong, l°-2° high, 3'-5' wide, rather rigid, erect ; pinnae triangular- 

 ovate, broadest at base, pinnatifid almost to the midrib, divisions not 

 many, oblong, obtuse, finely serrate, the largest ones sometimes toothed 

 or pinnatilid-lobed ; fruit dots half way between midvein and margin. 



Var. Clintonianum, Eaton. In swampy woods, N., is very much 

 larger every way, with fruit dots nearer the midvein, and is often mis- 

 taken for A. Goldianum. 



A. Floridinum, Eaton. Wet woods, Fla. ; lower pinnae triangular- 

 lanceolate and sterile, but the upper ones fertile, narrower, and longer, 

 with very short, obtuse, rather distant divisions, which are decurrent on 

 the winged, secondary rhachis. 



•1- t- Fronds imperfectly evergreen, twice or thrice pinnate; the divisions 

 cut-toothed or incised; fruit dots not near the margin; indusium rather 

 small, withering away. 



A. spinul6sum, Swartz. Shady woods, very common N. ; fronds thin, 

 oblong-ovate ; pinnae oblong-lanceolate, the lower ones broader and some- 

 what triangular; pinnules very numerous, oblong-ovate, pinnately in- 

 cised ; the oblong lobes with spinulose teeth toward the ends ; indusium 

 smooth or minutely glandular at the margin. Has several forms. 



Var. dilatatum. Hook. In mountainous places and cool woods, K. 

 Eng. to Minn., and N., is larger, broader in outline and oftenest 3-pin- 

 nate ; pinnules lance-oblong, the lowest greatly elongated ; indusium 

 smooth and naked. 



A. Bo6ttii, Tuckm. Swampy woods N. ; 2°-3° high, of narrow out- 

 line, barely twice pinnate, with oblong-ovate toothed pinnules, or the lower 

 ones pinnatifid ; indusium minutely glandular ; sterUe fronds smaller and 

 simpler than the fertile ones. 



••- I- •»- Fronds fully evergreen, thickish, about twice-pinnate ; fruit dots 

 near the margin; indusium thickish, convex, persistent. 



A. margin^e, Swartz. Rocky woods, common N. ; fronds l°-2° long, 

 ovate-oblong, bluish-green, the stalk very chaffy ; pinnae lanceolate, 3'-5' 

 long; pinnules oblong, often curved, entire, or obtusely toothed, attached 

 by a broad base to the narrowly winged, secondary rhachis ; fruit dots 

 close to the margin, rather large. 



§ 2. PoLYaxiCHCM. Indusium orbicular, peltate, attached by the center to 

 a short stalk; veins forking, free. 



A. acrostichoides, Swartz. Christmas Fern. Fronds l°-2° high, 

 growing in crowns, with chaffy rootstocks and stalks, evergreen, shining, 

 lanceolate, simply pinnate ; pinnae numerous, oblong-lanceolate from an 

 unequal half-halberd-shaped base, serrulate with bristle-pointed teeth, 

 rarely incised, upper ones of the fertile frond smaller and bearing copious, 

 soon confluent fruit dots. Common in woods ; often used in Christmas 

 decorations. 



§3. Cyrtomium. /nfZMSiwm as rn § Poltstiohum. Fronds once pinnate ; 



veins pinnate from the midrib, pinnately branching; the veinlets reticu- 

 ■ lated and forming arched meshes with 1-3 free included veinlets rising 



from the base of the arch. 



A. falcafum, Swartz. Cult, from Japan, China, etc., and very variable ; 

 fronds l°-2° high, 5'-9' broad ; base of stalk chaffy with large scales ; 

 pinnae thick and .shining, end one large and rhomboid or halberd-shaped ; 

 side ones few or many, oblong- ovate, long-pointed, nearly entire, lower 

 side of base rounded, upper side angled or slightly auricled ; fruit dots in 

 manv rows on all or nearly all the pinnae. 



