Medium-sized or large ferns with greenish succulent stipes and 1-3-pinnate or pinnatihd blades; veins free; scales of the rootstock delicate, of thin-walled cells. .Sori usually curved, oblong to linear-oblong, or crossing the vein and recurved, sometimes unequally hippocrepi-form, rarely roundish. Indusia shaped like the sorus, attached as in Asplenium, subentire to fimbriate, rarely vestigial and concealed. [Greek, shieldless, of doubtful application.]

A genus of about 85 species, mainly of tropical regions. A. cyclosontm occurs in western North America. Type species: Athyrinm Filix-foemina (L.) Roth.

1. Athyrium Thelypteroides (Michx.) Desv. Silvery Spleenwort

Fig. 69

Asplenium acrostichoides Sw. Schrad. Journ. Bot. 18002: 54. 1801. Not Athyrium acrostichoideum Bory, 1836.

Asplenium thelypteroides Michx. Fl. Bor. Am. 2: 265. 1803.

Athyrium thelypteroides Desv. Mem. Soc. Linn. Paris 6: 266. 1827.

Rootstock slender, sinuous, creeping. Stipes 8'-16' long, straw-colored, somewhat chaffy below, at least when young; blades lanceolate, oblong-lanceolate, or ovate-oblong, 1°-3° long, 6'-12' wide, acute or acuminate, narrowed to the base, very deeply bipinnatifid; pinnae linear-lanceolate to oblong-lanceolate, sessile, acuminate, deeply pinnatifid into numerous oblong obtuse or subacute lightly serrate-crenate segments; sori crowded, curved or straight, the lower often double; indusium light-colored and shining when young.

In rich moist woods, Nova Scotia to Minnesota, Missouri and Georgia. Ascends to 5000 ft. in Virginia. Closely related forms occur in eastern Asia. Aug.-Oct.

1 Athyrium Thelypteroides Michx Desv Silvery Splee 691 Athyrium Thelypteroides Michx Desv Silvery Splee 70

2. Athyrium Filix-Foemina (L.) Roth. Lady-Fern. Female-Fern

Fig. 70

Polypodium Filix-foemina L. Sp. PI. 1090. 1753. Asplenium Filix-foemina Bernh. Schrad. Neues Journ.

Bot. 12: 26. 1806. A. Filix-foemina Roth, Romer's Arch. 21: 106. 1799.

Rootstock creeping or ascending, slender for,the size of the plant. Stipes tufted, 6-12' long, straw-colored, brownish or reddish; blades broadly oblong-ovate to oblong-lanceolate, acuminate, l°-3° long, 2-pinnate; pinnae lanceolate, acuminate, short-stalked or the upper ones sessile, 4'-8' long; pinnules oblong-lanceolate to broadly elliptical, incised or serrate, the lobes or teeth often again toothed, those toward the ends of the pinnae confluent; sori short; indusia straight or curved, sometimes horseshoe-shaped.

In woods and thickets, Newfoundland to British Columbia, the Gulf states, and California. Ascends to 6000 ft. in North Carolina, and to 2000 ft. in Vermont. Europe and Asia. June-Aug. Backache-brake.

Blades bipinnatifid; segments lightly crenate-serrate.

1.

A. thelypteroidcs.

Blades bipinnate; pinnules variously incised or deeply serrate.

2.

A. Filix-foemina.