Montana Field Guide

Plant: Loose tufts. Dark green with red-brown stems. Stems erect, simple, 1-5 cm tall. Rhizoids mostly at the base of stem.

Leaf: When dry, slightly contorted. Leaves obovate to somewhat orbicular, 4-9 x 3-7 mm. Apex rounded or rarely with a short apiculus. Costa red, broad at base, and narrowing toward apex. Costa usually ends before apex.

Leaf Cells: Median laminal cells more-or-less hexagonal or a little elongate in oblique rows. Median cells near costa are 70-170 x 50-70 µm, typically 120-130 µm long, and becoming shorter towards margin (30-60 µm long). In surface (transverse) view the laminal cell walls appear evenly thick and not pitted. However, in X-S view the horizontal cell walls are thin and the vertical cell walls are thick dorsally and ventrally and thin in between. Marginal cells are long and narrow, in 1-2 rows near apex, and 2-3(4) rows below apex. In X-S the marginal cells of the apex are of 1-layer and of 2-4 layers below the apex. The marginal cell walls are thick and pitted in X-S.

Seta/Capsule: Seta is 1-2.5 cm tall and red-brown. Capsules are inclined to pendant, yellow-brown, ovoid, rounded to seta, neck hardly differentiated, 2.5-3.5 long, and irregularly wrinkled when dry.

This species differs from Rhizomnium species by its naked stem, leaves hardly contorted when dry, the unusual cell walls in X-S, and the short operculum. All Rhizomnium species lack marginal teeth while Plagiomnium species have single-toothed margins and Mnium species have double-toothed margins.

On moist soil in the woods and along streams. Lowlands to about 6,600 feet elevation.

Dioicous. Seta is 1-2.5 cm tall and red-brown. Capsules are inclined to pendant, yellow-brown, ovoid, rounded to seta, neck hardly differentiated, 2.5-3.5 long, and irregularly wrinkled when dry.