Athyrium

Plants generally terrestrial. Stems short-creeping or ascending, stolons absent. Leaves monomorphic, usually dying back in winter. Petiole ± 0.5 times length of blade or less, base swollen and dentate, persisting as trophopod over winter or not; vascular bundles 2, lateral, lunate in cross section. Blade lanceolate to elliptic or oblanceolate, 1–3-pinnate-pinnatifid, gradually reduced distally to confluent, pinnatifid apex, herbaceous. Pinnae not articulate to rachis, segment margins serrulate or crenate; proximal pinnae often reduced, sessile to short-petiolulate, ± equilateral; costae adaxially grooved, grooves continuous from rachis to costae to costules; indument absent or of linear to lanceolate scales or 1-celled glands abaxially. Veins free, simple or forked. Sori in 1 row between midrib and margin, round to elongate, straight or hooked at distal end, or horseshoe-shaped; indusia shaped like sori, persistent, attached laterally or with narrow sinus, or indusia absent. Spores brownish, rugose. x = 40.

Distribution

Worldwide.

Discussion

In species outside the flora stems are sometimes long-creeping to erect, with leaves radially or dorsiventrally arranged.

Species about 180 (2 in the flora).

Selected References

Johnson, D. M. 1986b. Trophopods in North American species of Athyrium (Aspleniaceae). Syst. Bot. 11: 26--31.

Kato, M. 1977. Classification of Athyrium and allied genera of Japan. Bot. Mag. (Tokyo) 90: 23--40.

Liew, F. S. 1972. Numerical taxonomic studies on North American lady ferns and their allies. Taiwania 17: 190--221.

Lower Taxa

Athyrium distentifolium, Athyrium filix-femina

Key

1	Sori round, submarginal; indusia much reduced or usually absent.	Athyrium distentifolium var. americanum
1	Sori elongate or hooked, medial; indusia well developed.	Athyrium filix-femina