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 lacking. Spores 6--10 µm.

Moist, acidic boulders; montane, predominantly alpine; B.C.; Alaska, Oreg., Wash.; Japan.

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