Montana Field Guide

Plants: Pleurocarpous (Vitt 1988), growing in “dense, pendent wefts,” somewhat yellow to deep green, and moderately shiny (FNA 2014). Main stems prostrate (Smith 1980) with stipe short or wanting, the secondary stems 20-40 mm in length (FNA 2014), upright, somewhat tree-like to prostrate and erratically branched (Smith 1980), the branches occasionally a little crowded and bowing downward; long, tapering branches often present, their leaves smaller and more slender; hyalodermis wanting; paraphyllia wanting; pseudoparaphyllia leaf-like, occasionally dentate; stems radiculose (FNA 2014).

Leaves: Main stem leaves widely deltoid or sometimes more slenderly so, the leaf tip occasionally thin and tapering narrowly, the leaf edges almost smooth, and the costa sometimes lacking. Branch leaves egg-shaped to lance-shaped with ovate tendencies, the edges dentate all over and more conspicuously so in the apiculus, the costa sometimes reaching 2/3 of the way up the leaf (FNA 2014).

Leaf Cells: Alar cells of the main stem leaf hardly distinct, the alar area small. Alar area of the branch leaves well-delineated and occasionally suddenly concave. Medial cells of the lamina longer than 5:1 (FNA 2014).

The closely related Isothecium stoloniferum is highly variable and has a morphotype that is frequently indistinguishable from Isothecium myosuroides (FNA 2014).

Stones and boulders, bluffs, bottoms of trees, shaded habitats in woods. Occurring from lowlands to mid-elevations (FNA 2014).

Sporophytes uncommon. Seta smooth, russet, 10-20 mm tall. Capsule sometimes reaching 1.5 mm in length; operculum cone-shaped; peristome with both exostome and endostome, yellow; exostome processes with exterior transverse ridges below and papillae above. Calyptra draping hood-like (FNA 2014).