Stems compact, erect to ascending, with cluster of persistent petiole bases of ± equal length; scales uniformly brown, lanceolate. Leaves 3.5--15 × 0.5--1.2 cm. Petiole green or straw-colored throughout, articulate above base at swollen node, somewhat pliable and resistant to shattering. Blade linear to linear-lanceolate, pinnate-pinnatifid proximally, glabrous or with occasional sessile glands, never viscid; rachis glabrous. Proximal pinnae fan-shaped, wider than long; distal pinnae ovate-lanceolate, longer than wide, abruptly tapered to a rounded or broadly acute apex; largest pinnae with 1--3 pairs of pinnules, abaxial and adaxial surfaces glabrous. Pinnules entire or broadly crenate; margins nonlustrous, thin, lacking cilia or translucent projections. Vein tips slightly (if at all) enlarged, barely visible adaxially . Indusia of narrow hairlike segments, these uniseriate throughout, composed of cells many times longer than wide, usually surpassing mature sporangia. Spores averaging 39--45 µm. 2 n = 78. Sporulating summer--early fall. Shaded cracks and ledges on cliffs; mostly calcareous rocks, especially limestone; 0--1500 m; Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., Que., Sask., Yukon; Alaska, Maine, Minn., N.H., N.Y., Vt.; n Eurasia. Woodsia glabella is a well-marked species occasionally confused with narrow, glabrescent forms of W . alpina and W . oregana subsp. oregana . These taxa are readily distinguished from W . glabella by their petioles, which are reddish brown or dark purple near the base.
Rhizome scales lanceolate, 3-4 נ1-1.5 mm, brown, concolorous, denticulate, not ciliate; lvs 5-16 cm; petiole stramineous, glabrous, scaly only at the base, articulate below the middle; blade linear, pale green, 8-14 mm wide, slightly narrowed below, glabrous and scaleless, pinnate, with green rachis; pinnae sessile, 8-14 pairs, suborbicular to deltoid, 5-9 נ5-6 mm, rounded to acute, trilobed or pinnatifid with 2-3 pairs of entire or crenate segments; indusium a minute disk with a ring of numerous long, brown, septate marginal hairs; 2n=78. Calcareous rocks; circumboreal in Amer. from Nf. to Alas., s. to N.S., Mass., n. N.H., n. Vt., N.Y. (Adirondack and Catskill Mts.), Ont. and B.C.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.