6. A. ebèneum, Ait. Fronds upright (9–18´ high), linear-oblanceolate in outline, fertile ones much the taller; pinnæ (6–18´´ long) firmly membranaceous, mostly alternate, sessile, spreading, oblong or oblong-linear, finely serrate or even incised, the base auricled on the upper or both sides; sori many, nearer the elongated midvein than the margin; stipe and rhachis blackish-purple and shining.—Rocky, open woods; rather common.
[*][*][*] Small evergreen ferns; the broader fronds 1–3-pinnate; pinnæ incised.
7. A. Bradlèyi, D. C. Eaton. Fronds oblong-lanceolate, 4–7´ long, besides the blackish and somewhat shining stipe, membranaceous, pinnate; pinnæ rather numerous, the lower ones no larger than the middle ones, all short-stalked, oblong-ovate, obtuse, incised or pinnatifid into oblong toothed lobes.—On rocks, Ky. and southward; rare. A single plant has been gathered near Newburg, N. Y.—Intermediate between A. ebeneum and A. montanum.
8. A. montànum, Willd. Fronds ovate-lanceolate from a broad base (2–5´ long), subcoriaceous, pinnate; pinnæ ovate-oblong, the lowest pinnately cleft into oblong or ovate cut-toothed lobes, the upper gradually simpler; rhachis green, broad and flat; stipe brown at base.—Cliffs and rocks, from Conn. and Penn. to Ky., and southward. July.
9. A. Rùta-murària, L. Fronds deltoid-ovate (1–2½´ long), subcoriaceous, laxly 2–3-pinnate at base, the pinnæ alternate; ultimate segments few, stalked (2–5´´ long), from narrowly cuneate to roundish-obovate, toothed or incised at the apex; veins forking; sori 2–4 on a segment.—Limestone cliffs, Vt. to Mich., and southward; scarce. July. (Eu.)
[*][*][*][*] Tall ferns (2–4° high), not evergreen; fronds pinnate or sub-bipinnate.
10. A. angustifòlium, Michx. Fronds thin, simply pinnate; pinnæ numerous, short-stalked, linear-lanceolate, acuminate, entire or crenulate (3–4´ long), those of the fertile frond narrower; fruit-dots linear, 20–40 each side of the midvein; indusia slightly convex.—Rich woods, W. New Eng. to Wisc., and southward along the mountains. Sept.
11. A. thelypteroìdes, Michx. ([Pl. 18], fig. 1, 2.) Fronds (2–3° high) pinnate; pinnæ deeply pinnatifid, linear-lanceolate (3–5´ long); the lobes oblong, obtuse, minutely toothed, crowded, each bearing 3–6 pairs of oblong fruit-dots, some of them double.—Rich woods; not rare. July–Sept.
§ 2. ATHÝRIUM. Indusium delicate, curved, often crossing the vein, and attached to both sides of it, thus becoming reniform, or shaped like a horseshoe.
12. A. Filix-fœ́mina, Bernh. Fronds (1–3° high) ovate-oblong or broadly lanceolate, twice pinnate; pinnæ lanceolate, numerous; pinnules confluent on the secondary rhachis by a narrow margin, oblong and doubly serrate, or elongated and pinnately incised with cut-toothed segments; fruit-dots short, variously curved, at length confluent.—Moist woods; common and presenting many varying forms. July. (Eu.)