Plants very small, in tufts, brownish proximally, golden green distally. Stems 3–4 cm, 0.5 mm wide, erect to ascending, sparsely branched. Leaves closely appressed-imbricate, straight, broadly ovate, not or slightly plicate, 0.6–0.8 mm; margins plane, slightly serrate distally; apex abruptly very short-acuminate to apiculate; ecostate; basal laminal cells shorter than medial cells, deeply pigmented; medial cells oblong to oblong-rhombic, 35–40 × 9 µm. Specialized asexual reproduction absent. Sporophytes unknown.

Habitat: Wet calcareous habitats, Arctic tundra
Elevation: low to moderate elevations

Distribution

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• Legacy Map

Greenland, N.W.T., Nunavut, Alaska.

Discussion

Orthothecium acuminatum is distinguished by stems 0.5 mm wide and up to 4 cm long, with straight, broadly ovate, abruptly short-acuminate to apiculate leaves. The branches are often slender and stoloniferous, bearing minute leaves. The species is known in mainland North America only from a few localities in the Northwest Territories and one locality in Alaska. W. A. Weber (pers. comm. to R. R. Ireland) suggested that O. diminutivum (Grout) H. A. Crum & L. E. Anderson, described from Colorado, is synonymous with Isopterygiopsis pulchella (Hedwig) Z. Iwatsuki.

Selected References

None.

Lower Taxa

None.