Western spleenwort

Asplenium trichomanes Linnaeus var. vespertinum (Maxon) Jepson

Roots not proliferous. Stems short-creeping, rarely branched; scales black with lighter margins, linear-lanceolate, 2--3 × 0.2--0.4 mm, margins entire, or denticulate distally. Leaves monomorphic. Petiole reddish brown or purplish black throughout, lustrous, 2--5 cm, 1/4--1/6 length of blade, sometimes curved like a J at base; indument of blackish brown, filiform scales at base. Blade linear, 1-pinnate throughout, 5--15(--28) × 1--2.5 cm, thick, glabrous; base gradually tapered; apex acute, not rooting. Rachis reddish brown or purplish black throughout, shiny, glabrous. Pinnae 15--30 pairs, oblong; medial pinnae 5--10 × 2--3 mm; base rounded to cuneate; margins lobed or serrate; apex obtuse. Veins free, obscure. Sori 2--6 pairs per pinna, on both basiscopic and acroscopic sides. Spores 64 per sporangium.

Moist, shaded canyon walls and at base of overhanging rocks; 0--1000 m; Calif.; Mexico in Baja California.