Adiantum capillus–veneris L., . Perennial herb, evergreen, rhizomatous, fibrous–rooted, canopy ± closed with ascending, spreading, and drooping to pendent leaves, < 50 cm tall; shoots glabrous; young fiddleheads ca. 4 mm diameter; rhizomes vertical and creeping, axis 12—40+ × 2—4 mm, light brown, densely scaly, bearing hairy adventitious roots and persistent petiole bases, the scales awl–shaped flared at base, 1.5—3 × 0.2—0.5 mm, light to golden brown and ± transparent, entire or sometimes slightly toothed on 1 side, netted–veined, the veins conspicuous and opaque brown.
Leaves (fronds) helically alternate, odd–2(—3)–pinnately compound to 1–pinnate above midpoint, 60—300+ mm long, petiolate; petiole (stipe) channeled, 20—150+ mm long, 0.6—1.5 mm wide at base, glossy dark reddish brown to almost black, bearing scales like on rhizome, the scales dense at base becoming widely spaced above, not flared, decreasing in length upward; blade lanceolate in outline, 50—200 × 20—120 mm, with 6—23 primary divisions, the divisions alternate and widely spaced, below midpoint 1–divided or 2–divided; rachis wirelike, glossy brown to dark reddish brown or almost black, slightly flexuous at base becoming more so toward tip; secondary axes diverging from main axis 30—60°, straight to slightly zigzagged; petiolules 0.3—4.5 mm long (lateral leaflets) to 8 mm long (terminal leaflets); blades of ultimate leaflets (pinnules) fan–shaped, subrhombic, or wedge–shaped and often markedly asymmetric, 4—27 × 4—31 mm, 0—7–lobed, thin, dull light green, broadly tapered at base, minutely dentate on margins except where folded under to form false indusium, the sinuses between lobes 0.6—10 mm deep, dichotomously veined, the veins free at tips, grading from same dark color as petiolule at base to greenish approaching margin, with each vein terminating in a short tooth; false indusia typically 2—7(—9) per leaflet (± corresponding to number of lobes), 0.8—1.3 × 1—4.5 mm.
Sori absent.
Sporangia ± 0.2 mm wide, brown, forming submarginally on lower surface of leaflet under false indusium.
Spores yellowish brown. January—December (fertile sporangia always present).
A. C. Gibson & B. A. Prigge