Hypnum robustum Hooker, Musci Exot. 2: plate 108. 1819 (as Hypnunum on plate)

Plants to 12 cm. Stems hooked at apices. Stem leaves 1.2-2.2 mm wide; alar cells shorter, wider than basal cells, 18-38 × 12-25µm; medial laminal cells 40-90 × 5-9 µm. Branch leaves 2.2-4 × 0.9-1.3 mm. Seta 1.7-3 cm. Capsule arcuate when dry, ellipsoid when moist, 2-3.4 mm.

Soil, litter, and rock in montane coniferous forests of Pacific Northwest, occasionally extending into alpine tundra; moderate to high elevations (300-2500 m); Alta., B.C.; Alaska, Colo., Idaho, Mont., Oreg., Wash.

Plants of Rhytidiopsis robusta in subalpine forest and alpine tundra are generally smaller, with leaves 2.5-3.5 mm and leafy stems 3-4 mm wide.