FERN FAMILY. J369 



midrib; divisions very numerous, nearly 1' long, somewhat scythe-shaped, 

 rather acute, serrate with incurved teeth ;* fruit-dots very near the midvein. 



A. cfristatum. Wet places in woods, common : fronds narrowly oblong, 

 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 pinnatirid-lobed ; fruit-dots 

 half-way between midvein and margin. Var. CLIXTOXI XXUM, in swampy 

 woods, N., is very much larger every way, with fruit-dots nearer the midvein, 

 and is often mistaken for A. Goldianum. Var. FLORID\XUM, in wet woods 

 8., has the 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. 



*- +- Fronds imperfbtHf evergreen, twice or thrice pinnate : the divisions cut- 

 toothed or incised : fruit-dots not near the margin : indusium rather small, 

 withering awny. 



A. spinul6sum. Shady woods, very common N. : fronds thin, oblong- 

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

 lar ; pinnules very numerous, oblong-ovate, pinnately incised, the oblong lobes 

 with spinulose teeth toward the ends ; indusium smooth or minutely glandular 

 at the margin. Has several forms. Var. DILATATUM. in mountainous places, 

 N., is larger, broader in outline and commonly but twice pinnate; pinnules of 

 the lowest pinnae greatly elongated. Var. BOOTTII, in swampy woods N., is 

 2 -3 high, of narrow* outline, barely twice pinnate, with oblong-ovate toothed 

 pinnules, or the lower ones pinnatifid : it runs apparently into A. cristatum. 



*--*- Fronds fall i] ew-rgren, thickish. about twice-pinnate : fruit-dots mar the 



margin : indusium thicLish, convex, persistent. 



A. marginale. Hocky woods, common N. : fronds l-2 long, ovate- 

 oblong, bluish-green, the stalk very chalfy ; pinnae lanceolate, 3' -5' long; 

 pinnules oblong, often curved, entire or obtusely toothed, attached by a broad 

 base to the narrowlv winged secondary rhachis ; fruit-dots close to the margin, 

 rather large. 



2. PoLTSTXCHUM. Indusium orbicular, peltate, attached by the centre to a 

 short stalk: veins forking, free : w Id sped s of the country. 



A. acrostichoides. Rocky woods, common ; fronds 1 -2 high, grow- 

 ing in crowns, with chalfy rootstocks and stalks, evergreen, shining, lanceolate, 

 simply pinnate ; pinna? 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. 



3. CYRT^.MIUM. Indusium. as in POLYSTICHUM. Fronds once p Innate : 

 veins pinnate from the midrib, j>inn(tie/)/ /'ranching, the veinle's reticulated 

 and for min< i arched meshes with 1-3 free included veinlets rising from the 

 base of the arch: exotic. 



A. falcatum. Cult, from Japan: fronds 1- 2 high, 5' -9' broad; base 

 of Stalk chaffy with large scales; pinna; thick and shininir, end one large and 

 rhomboid or halberd -shaped ; side ones few or many, oblong-ovate, long-pointed, 

 nearly entire, lower side of base rounded, up;>er side angled or slightly auricled ; 

 fruit-dots in many rows on all or nearly all the pinnae. 



16. CYSTOPTERIS. (Greek for Bladdr Frrn^ alluding to the thin, 

 sometimes inflated indusium.) Species few, mosrly Northern. 

 C. fragilis. Shaded or moist rocky places, common N. : fronds very deli- 

 cate, 4' -8 'long, with slender stalks, oblong- ovate, twice-pinnate; pinnae with 

 a narrowly margined rhachis ; pinnules oblong or ovate, toothed or incised, very 

 variable ; indusium pointed at the upper end 



C. bulbifera. Wet places, oftenest in ravines, from N Carolina N. : 

 fronds l-3 liigh, 3' -5' wide at the base, narrowed above and much elon- 

 gated, twice pinnate, bearing scattered bulblets beneath ; pinnules oblong, ob- 

 tuse, toothed or pinnatifid ; i-ndusium roundish, truncate on the upper side. 



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