Schistidium robustum

Plants in open to compact tufts, olivaceous, sometimes brownish or yellowish. Stems 1–5 cm, central strand distinct. Leaves erect or curved when dry, narrowly ovatelanceolate to ovatelanceolate, sharply keeled distally, 1.6–3 mm, 1-stratose, rarely with 2-stratose striae distally; margins recurved to near apex, smooth, 1-stratose or 2-stratose; apices acute, rarely somewhat obtuse; costa usually long-excurrent as a spinulose-denticulate, usually decurrent awn, rarely percurrent, smooth; basal marginal cells quadrate or oblate, trigonous; distal laminal cells short-rectangular, occasionally isodiametric, 8–11 µm wide, strongly sinuose. Sexual condition autoicous. Capsule light-brown or redbrown, cylindric to elongate-cylindric, (0.8–) 1–1.6 mm, sometimes striated; exothecial cells mostly irregularly shaped, mainly elongate, with numerous isodiametric and, sometimes, a few oblate cells, walls thin-walled to unevenly thickened and somewhat curved, usually trigonous; stomata present; peristome patent to squarrose, sometimes twisted, 300–430 µm, red or orange-red, densely papillose, entire or weakly perforated. Spores 8–11 µm, nearly smooth.

Phenology: Capsules mature late spring to early summer.
Habitat: Dry to periodically moist calcareous rock
Elevation: moderate to high elevations (400-2100 m)

Alta., B.C., Nfld. and Labr. (Nfld.), N.W.T., Ont., Que., Yukon, N.Dak., S.Dak., Wash., Europe

Discussion

The long, spinulose-denticulate and decurrent awns, strongly sinuose laminal cells, and brown or red-brown, cylindrical capsules with primarily elongate exothecial cells are characteristic features of Schistidium robustum.

Selected References

None.

Lower Taxa