Montana Field Guide

Plants: Pleurocarpous, growing in masses (Crum and Anderson et al. 1981) to 50 cm in length, shiny (FNA 2014) or dull (Flowers 1973), green, light green, green with yellow tones, or somewhat brown (FNA 2014), frequently almost black with age (Lawton 1971). Stems irregularly branched; tips of the stems and branches somewhat stiff and long-tapering (FNA 2014), the stems stiff and tough proximally (Flowers 1973); central strand wanting; axillary hairs consisting of 5-7 cells, the first cell square and red (FNA 2014).

Leaves: Those of branches and stems alike, except branch leaves a little smaller (Lawton 1971), spreading a little to over 45 degrees when dry, spreading a little when damp, in 3 vertical rows along the stem (FNA 2014), typically overlapping at stem and branch apices (Lawton 1971), strongly folded longitudinally (FNA 2014), the keel only a little curved if at all (Crum and Anderson et al. 1981), 2-5 mm in length, lance-shaped, sometimes tending to oblong or ovate, tapering to the acute to widely acute apex; base extending down the stem; leaf edges occasionally lightly bent back and downward when dry, flat when damp (FNA 2014), smooth or occasionally very finely saw-toothed distally (Lawton 1971); costa absent or scarcely developed (FNA 2014).

Leaf Cells: Medical cells of the lamina long and slender, tapering at the ends, to long and narrowly diamond-shaped (FNA 2014), longer than the apical cells (Flowers 1973); alar cells oblong, swollen, the walls flaccid (FNA 2014), rusty (Flowers 1973) or brown, short-rectangular, the region fairly well-delineated (Crum and Anderson et al. 1981).

Affixed to stones, boulders, small dead branches (FNA 2014), submerged in low, running water (Crum and Anderson et al. 1981) and in pools (Elliott and Pipp 2016); occurring from lowlands to about 11,150 elevation (FNA 2014).

Dioicous. Perigonia bud-like, the bracts about 1.4 mm. Perichaetial bracts to 3.5 mm (FNA 2014), occasionally narrowing suddenly to form an apiculus or cusp (Lawton 1971). Seta short, 0.2-0.3 mm tall. Capsule 2-2.5 mm in length, hidden amongst the bracts to barely exposed, without stomata; operculum cone-shaped; exostome teeth 16, slender and frequently joined at the distal ends in pairs, endostome forming a trellis, the segments joined by crosswise bars throughout (perfect). Calyptra cone-shaped and shielding the upper end of the capsule, hairless (FNA 2014).