FERN FAMILY. 497 



A. crist^tum, Swartz. Wet places in woods, frequent; fronds nar- 

 rowly oblong, l°-2° high, 3'-5' wide, rather rigid, erect ; pinnse triangular- 

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

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

 or pi)uiatifid-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. Floridanum, ICaton. Wet woods, Fla. ; lower pinnse 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 rhacliis. 



-1- H- Fronds imperfectly evergreen^ twice or thrice jailmate; 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 ; pinnaj oblong-lanceolate, the lower ones broader and some- 

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

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

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



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

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

 naie ; 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 ; sterile fronds smaller and 

 simpler than the fertile ones. 



^- •(- -1- Fronds fully evergreen, thickish, about twice-pinnate; fruit dots 

 near the margin; indusium thickish, convex, persistent. 



A. marginile, Swartz. Rocky woods, common N. ; fronds l°-2° long, 

 ovate-oblong, bluish-green, the stalk very chaffy ; pinna? 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 margm, rather large. 



§ 2. PoLYSTicHUM. Indusiiuu 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 ; pinnse 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. /H^Msmm «s m § Polystichum. 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. falcatum, Swartz. Cult, from Japan, China, etc., and very variable ; 

 fronds \°-l^ higli, 5'-9' broad ; base of stalk chaffy with large scales ; 

 pinniB thick and shining, end one large and rhomboid or halbcrd-shapt'il ; 

 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 

 many rows on all or nearly all tiie pinnaj. 



gray's F. v. & G. BOT. 32 



