Smooth cliff fern, woodsie glabre

Woodsia alpina (Bolton) Gray var. glabella (R. Brown ex Richardson) D. C. Eaton; W. hyperborea (Liljeblad) R. Brown ex Richardson var. glabella (Richardson) Watt

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.