Woodsia alpina (Bolton) S.F. Gray
Habitat: Shaded or exposed, damp to dry slaty or calcareous rocky banks. [Rocky summits and outcrops (non-forested, upland)]
Range: Labrador to Alaska, Maine, northern New York and western Ontario. Also in Greenland.
Aids to Identification: Cliff ferns (Woodsia) are largely slender ferns of ledges, cliffs, and talus slopes. They are recognized by their distinctive indusia and petioles. Cliff ferns have an inferior indusium (positioned under the sporangium) that is lacerate into slender filaments. The petiole bases have a swollen node where the upper part of the petiole is articulated. All the petioles break off at the same point so that the persistent leaf stalks are all the same length. Woodsia alpina is sparsely pubescent with hairs, glands, and scales, but the undersurface of the leaflets usually are devoid of hairs. The leaves (fronds) are 1-3 cm wide by 5-15 cm long, and each leaflet is comprised of 2 or 3 divisions. The brown, chaffy stalk and smooth leaves differentiate it from two ferns with which it often occurs. The common Rusty woodsia (W. ilvensis) has rusty hairs both on the stalk and the underside of the frond, and smooth woodsia (W. glabella) has no hairs.
Ecological characteristics: Ecological relationships in Maine are not well known.
Synonyms: Acrostichum alpinum Bolton; Woodsia alpina (Bolton) S.F. Gray var. bellii Lawson; Woodsia glabella R. Br. ex Richards. var. bellii (Lawson) Lawson.
Known Distribution in Maine: This rare plant has been documented from a total of 7 town(s) in the following county(ies): Aroostook, Oxford, Piscataquis, Somerset.
Reason(s) for rarity: At southern limit of its range; suitable habitat rare in Maine.
Conservation considerations: Populations are small and therefore vulnerable to the vagaries of small populations like random fluctuations or localized disturbance events. Known populations are not particularly vulnerable to human activities.