Plants in olive green loose cushions or wefts to 1 cm high, almost lustreless. Leaves rather closely inserted, erect-spreading when moist but with the tips strongly inflexed when dry, not at all secund, somewhat inrolled and with inflexed apices when dry, not keeled, to 2 mm long, 3–4: 1, broadest immediately above the base, neither plicate nor fragile, ovate lanceolate to elliptic. Leaf lamina unistratose or with a few bistratose streaks, with median cells quadrate with rounded lumens, to 10 µm wide, little different near margins, opaquely unipapillose with high and often forked papillae, in regular rows, not at all pitted, often somewhat collenchymatous. Basal juxtacostal cells pellucid but rather thick walled, rectangular, to 4: l. Basal marginal cells similar to the median cells. Costa filling about 1/6 of leaf at base, tapering and ending within a few cells of the obtuse to broadly rounded apex. Costa cross-section with two strong stereid bands, with guide cells well demarcated and with both epidermises well differentiated and chlorophyllose. Margin plane to erect, papillose crenate below but with a few spiculose enlarged cells forming denticulations near apex, mostly unistratose. Stem cross-section with small central strand, with large and leptodermous interior cells and with 2–3 layers of small pachydermous outer cortical cells.
Dioicous with male and female plants similar. Perigonia terminal. Perichaetial leaves spreading, similar to adjacent vegetative leaves. Consistently monosetous with the seta to 10 mm, yellow, straight and smooth. Urn arcuate and asymmetrical, short cylindrical, to 1 mm long, about 2: 1, sulcate and strumose. Operculum rostrate, about as long as urn. Annulus essentially undifferentiated. Peristome yellow brown, inserted at capsule mouth, to 400 µm long, divided to or below the middle, vertically low striate proximally but papillose distally. Exothecial cells to 20 µm wide, in irregular vertical rows, quite irregular in size and shape, rectangular 1–3: 1, thick walled with lumen/wall ratio 2–4: 1. Spores to 15 µm, lightly papillose.
Preston Peak (check in Dewey's publication for D. olympicum from Idaho - Dewey 589). Find a label for Norris 23204).