Woodsia R. Br.
Cliff fern, named for the English botanist Joseph Woods.
Polypodiaceae, fern family.
Prodr., 158. 1810.
Vegetative morphology. Plants perennial herbs; 1–15(–20) cm high; caespitose (loosely clustered); usually growing on rock, with stems compact to creeping and with erect to ascending unbranched, but rarely horizontal, fronds arising close together, from a cluster of persistent petiole bases. Roots black. Ground-level or under-ground stems horizontal; stoloniferous; compact. Leaves in a basal tuft (from the ground-level stems); alternate; compound; existing for a single season or less, or marcescent. Petioles (10–)15–30(–50) mm long; glabrous, or hairy; hairs more than the diameter of the petiole (if applicable). Blades 30–150(–250) mm long; (2–)5–25(–35) mm wide. Blades circinate when young (becoming linear or lanceolate mature fronds); with inconspicuous veins. Blades adaxial surface glabrous, or hairy. Blades adaxial surface hairs long-silky. Blades abaxial surface glabrous, or hairy. Blades abaxial surface hairs sparse, or very dense. Conspicuous hydathodes present (slit-like), or absent (not visible). Leaf apices acute. Leaflet arrangement pinnate.
Reproductive morphology. Sporangia in sori on the under-surface of the leaves. Sori with a distinct indusium. Indusia of narrow hair-like segments, one row of cells many times longer than wide, and longer than the sporangia.
Chromosome information. 2n = 78, 82, and 160 (probably).
Distribution. Northern hemisphere distribution: circumpolar. Arctic, or low arctic, or alpine.
Notes. Woodsia is a well marked genus of ferns, with a base chromosome number of (X =39– 41). The genus Cystopteris is probably the closest relative. Woodsia is distinguished by articulate bases to the petioles and the accumulation of petiole bases from older leaves. The veins of the pinnae are obscure, and end in slit-like hydathodes before reaching the leaf margins. The indusia are multilobed and the indusial segments are each a single row of cells that are much longer than wide. The Arctic Woodsia show close affinities to species found only in northern Eurasia (Windham 1993).
Illustrations. • Woodsia: cliff ferns. Woodsia: cliff ferns with jointed or articulated petioles that break at the joints and simple pinnae.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
