Polytrichum swartziiHartm. (redirected from: Polytrichum algidum Hag. & C. Jens.)
Family: Polytrichaceae
Swartz's polytrichum moss
[Polytrichum algidum Hag. & C. Jens., morePolytrichum commune subsp. swartzii (Hartm.) C. Hartm., Polytrichum commune var. swartzii (Hartm.) Nyh., Polytrichum inconstans I. Hagen, Polytrichum sinense Cardot & Thér.]
Plants: often rather soft and flexuose, green to blackish when old. Stems: 2–9 cm, simple, erect, in proximal part moderately to densely brownish tomentose. Leaves: 3–8 mm, loosely imbricate, appressed to erect-spreading and flexuose when dry, patent to widely spreading and weakly recurved when moist; sheath rectangular, scarcely narrowed to the blade; blade lanceolate to linear-lanceolate, often caducous at the junction of sheath and blade, the apex subulate, weakly channeled; marginal lamina 6–9 cells wide, distantly toothed to subentire; costa excurrent as short brown entire to serrulate tip, smooth abaxially or with a few teeth near apex; lamellae in profile entire to shallowly crenulate, 5–10 cells high, the marginal cells in section usually somewhat broadened, flat-topped or shallowly grooved, single or geminate, thin-walled, smooth, the marginal cells of lateral lamellae asymmetric; median sheath cells 75–110 × 2–12 µm, linear; cells of marginal lamina 9–15 µm, quadrate, thin- to firm-walled; perichaetial leaves with long sheathing bases and short subulate blade. Seta: 2.5–5 cm, reddish brown. Capsule: 2.5–3 cm, ± cubic, sharply 4–angled, suberect when mature, becoming horizontal when old; peristome teeth 64, 160–210 µm, obtuse, the basal portion 60–75 µm. Spores: 12–15 µm.
Very wet and regularly flooded situations, sedge meadows, wet tundra and lake shores (D. G. Long 1985). Greenland, Nfld. and Labr. (Labr.), N.W.T., Nunavut, Yukon, Alaska, Europe (Scandinavia), n, e Asia, Atlantic Islands (Iceland).
Polytrichum swartzii is a northern species with distantly toothed to subentire leaves, differing chiefly by the rounded-quadrate, flat-topped (not retuse or grooved) and scarcely-thickened marginal cells of the lamellae. The capsules are shortly cubic. In Nunavut, it is known from Baffin and Devon islands.