TEEN FAMILY. 869 



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

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



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

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

 at base, pinnatifid almost to the midrib, divisions not many, oblong, obtuse, 

 finely serrate, the largest ones sometimes toothed or pinnatifid-lobed ; fruit-dots 

 half-way between midvein and margin. — Var. CLiNTONiiifUM, in swampy 

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

 and is often mistaken for A. Goldianum. — Var. FlobidXndm, in wet woods 

 S., has the lower pinnse triangular-lanceolate and sterile, but the upper ones 

 fertife, naiTower and longer, with very short obtuse rather distant divisions, 

 which are decnrrent on the winged secondary rhachis. 



+- 4- Fronds imperf&th pvergreen, twice or thrice pinnate : the divisions cut- 

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

 withering awtiy. 



A. gpinnli^jjnm Shady woods, very common N. : fronds thin, oblong- 

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

 lar ; pinnules very numerous, oblong-ovatff, pinnately incised, the oblong lol)es 

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

 at the margin. — Has several forms. — Var. d ii.at.Vt.p m. in mountainous places, [ 

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

 the lowest pinnse greatly elongated. — Var. B <)6ttti. in sWampy woods N.; isv 

 2° -3° high, of narrow outline, barely twice pinmate, with oblong-ovate toothed 

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



^- ^- H- Fronds fully ev^rgrepn, tltickish, about fwice-pinnate : fruit-dots near the ^ 

 margin : indusium thiclcish, convex, persistent. 



A. margin&le. Rocky woods, common N. : fronds l°-2° long, ovate- 

 oblong,—blmshigVE5n, the stalk very chaffy ; pinuse lanceolate, 3' - 5' long ; 

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

 hose to the narrowly winged secondary rhachis ; fruit-dots close to the margin,' 

 rather large. 



§ 2. PoLYSTiCHUM. Indusium orhicitlar, peltate, attached by the centre to a 

 short st'itk: veins forking, free: wild species of the country. 



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

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

 simply pinnate ; pinnse numerous, oblong-lanceolate from an unequal hal^ 

 halberd-shaped b.ase, serrulate with bristle-pointed teeth, rarely incised, uppeK 

 ones of the fertile frond smaller and bearing copious soon confluent fruit-dots. 



■V^.3.^ CvRTdMiUM. - Indusium as in § Polystichum. Fronds once pinnate : 



veins pinnate from tlie midrib, pinnately branching, the veinlels reticulatrA 



and forming arched meshes with 1-3 f-ee 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 ; pinnse 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 many rows on all or nearly all the pinnse. 



16. CTSTOPTERIS. (Greek for Bladder Fern, alluding to the thin, 

 sometimes inflated indusium. ) Species few, mostly Northern. 

 S^C/ fr^gilis. Shaded or moist rocky places, common N. : fronds very deli- 

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

 a narrowjy 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°-3o high, S'-5' wide at the base, narrowed above and much elon- 

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

 tuse, toothed or pinnatifid ; indusium roundish, truncate on the upper side. 



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