Stems 2-5 mm. Leaves 1-2.5 mm, distal laminal cells mostly isodiametric, 1:1, with a few cells 2:1 or transversely elongate, areolation somewhat irregular, proximal cells longer. Seta 0.5-2 mm, flexuose when dry. Capsule spherical to short-ovate, 0.4-0.6 mm. Peristome absent. Spores 6-10 µm.

Moist, acidic boulders; montane, predominantly alpine; B.C.; Alaska, Oreg., Wash.; e Asia (Japan).

The spherical or short-ovate capsules absent peristome teeth and the somewhat shorter distal laminal cells distinguish Brachydontium olympicum from B. trichodes. This is a circum-North Pacific montane species, which should be sought for in coastal areas of Siberia.