FILICES. (ferns.) 593 



with a double indusium. — Mountains of Alabama, and northward. — Fronds 

 2' -5' high, with a winged greenish rachis, and a stipe nearly as long as the 

 frond. 



7. A. Ruta-muraria, L. Fronds small, ovate, pinnate above, bipinnate 

 below, the divisions stalked, obovate-euneate, tootbed at the apex ; veins forked 

 from the base ; fruit-dots few, indusia laciniate at the margin. — Rocks along 

 the mountains, and northward. — Fronds 2' - 4' high. 



8. A. myriophyllum, Presl. Fronds delicately membranaceous, lan- 

 ceolate, narrowed below, 2 - 3-pinnate ; ultimate segments obovate-oblong, en- 

 tire or 2-3-lobed; veins single in each segment or lobe, bearing below the 

 middle a solitary oblong fruit-dot. (A. Anchorita, Chapm. MS.) — On the walls 

 of a limestone cave at Schurlock's Spring, Jackson Co., Florida, Chapm. — 

 Fronds 3' -10' high, with short stipes and narrowly winged rachises. 



9. A. thelypteroid.es, Michx. Fronds ample, oblong-ovate, pinnate ; 

 the deeply pinnatifid pinnas lanceolate-acuminate from a broad sessile base ; the 

 lower ones smaller, distant, and deflexed ; the lobes oblong, obtuse, crenately 

 serrate; fruit-dots 8-12 to a lobe, at length confluent, those next the midrib 

 toward the ends of the pinnae mostly double ; indusium convex, thickish. — 

 Rich woods in the upper part of Georgia, and northward. — Fronds l°-3° 

 high. 



§ 2. ATHYRIUM, Roth. — Indusium thin, attached to the upper side of the vein ; 

 or recurved and crossing the vein, attached to both sides of it, thus becoming reni- 

 form or shaped like a horseshoe. 



10. A. Filix-foemina, Bernh. Fronds ample, ovate-oblong ; pinna? lan- 

 ceolate, numerous ; pinnules oblong or lanceolate, doubly serrate or variously 

 incised ; fruit-dots short, at length confluent. (Aspidium Filix-fcemina, Swartz.) 

 — Low shady woods, Florida to Mississippi, and northward. — Fronds l°-3° 

 high. — A. asplenoides (Aspidium asplenoides, Swartz?) is said to differ in hav- 

 ing a creeping caudex. 



12. CYSTOPTERIS, Bernhardi. 



Fruit-dots round, on the back of the free forking veins, covered when young 

 by a thin ovate or roundish hood-shaped indusium attached by the lower side 

 rather beneath the fruit-dot, its apex pointing toward the end of the vein, at 

 length reflexed or falling away. — Delicate Ferns with 2 -3-pinnate fronds, and 

 short creeping rootstocks. 



1. C. fragilis, Bernh. Fronds ovate-oblong, bipinnate; the ovate-lance- 

 olate pinna? mostly opposite, the lowest pair distant, smaller ; pinnules oblong 

 or obovate, cuneate at the base and decurrent on the winged secondary rachis, 

 variously toothed or incised ; indusium ovate, acuminate. (Aspidium tenue, 

 Swartz.) — Moist rocks on the mountains of North Carolina, and northward. — 

 Fronds 4' -8' long, on slender brownish stipes as long as the frond. Pinnules 

 varying greatly in shape and size. 



50* 



