POLYPODIA CEM. I O 5 



at base, often auricled, the lower much reduced ; texture sub- 

 coriaceous; veins flabellate ; sori i 2, linear-oblong, parallel 

 with lower edge of pinnae. Huachuca Mountains, Arizona. 



1 1 Rachis green, 



9. A. viride Huds. Stipes densely tufted, 2' 4' long, 

 naked, the lower part chestnut-brown ; fronds 2' 6' long, ' 

 broad, with 12 20 pinnae on each side, which are ovate or 

 rhomboidal in outline, the upper edge narrowed suddenly at 

 the base, the lower obliquely truncate, the outer part deeply 

 crenate ; rachis naked ; sori copious. Vermont, Canada, and 

 New Brunswick. 



10. A. dentatum L. Stipes tufted, 2' 6' long, naked, 

 ebeneous below; fertile fronds 2' 3' long, i' broad, with 6 8 

 pairs of stalked, oblong-rhomboidal pinnae, the lower side trun- 

 cate with a curve, the outer edge irregularly crenate ; sterile 

 fronds smaller on shorter stipes ; rachis naked ; sori copious in 

 parallel rows. Florida, South Carolina. 



tt Pinnce only 2 5, linear -cuneate. 



11. A. septentrionale (L.) Hoffm. Stipes dense, tufted, 

 3' 6' long, slender, naked, ebeneous toward the base; fronds 

 irregularly forking, consisting of two to five narrowly linear 

 rather rigid segments, which are entire or more frequently cleft 

 at the end into a few long narrow teeth ; sori elongate, placed 

 near the margin, usually facing each other in pairs, commonly 

 only two or three to each segment. Ben Moore, New Mexico 

 (Bigelow) ; Middle Mountains, Colorado, Arizona. 



ttt Pinna numerous, linear or linear-oblong, acute or acuminate. 



12. A. angustifolium Michx. Stipes i or more long, 

 brownish, slightly scaly below; fronds \\ 2 long, 4' 6' 

 broad, lanceolate-oblong, flaccid ; pinnae 2030 pairs, linear* 

 lanceolate, acuminate, entire or crenulate, those of the fertile 

 frond narrower ; texture thinly herbaceous ; sori linear, 2040 

 each side of the midvein. New England to Kentucky and Wis- 

 consin. 



13. A. firmum Kunze. Stipes 4' 8' long, erect, grayish, 

 naked; fronds 612' long, 34' broad; pinnae 1220 pairs, 

 oblong-lanceolate, the point bluntish, the margin inciso-cre- 

 nate, the upper one narrowed suddenly at the base, the lower 



