Montana Field Guide

Plants: Acrocarpous (Vitt 1988), trailing in water currents from wet stones, or growing in open tufts, deep green distally and darker proximally (Flowers 1973). Stems sometimes reaching 15 cm (Lawton 1971), without a central strand (FNA 2007); rhizoids growing from the base, along the stem, and from the abaxial costal surface below (Flowers 1973).

Leaves: Stem leaves closely spaced (FNA 2007), slightly bent and twisted (Lawton 1971) and upright to spreading about 45 degrees when dry (FNA 2007), spreading when wet, cupped (Lawton 1971), lance- to strap-shaped, narrowing to a curved or obtuse leaf tip, 2.8- 5 mm in length, 0.8-2.5 mm in width; leaf edges smooth below, saw-toothed above; base lightly embracing the stem; costa extending to the leaf tip (FNA 2007). Branch leaves similar to those of the stem (FNA 2007).

Leaf Cells: Lower laminal cells of similar length and width to short and oblong, those next to the costa sometimes very narrow or long and oblong; upper and medial cells square or nearly so, non-papillose, with thick walls; leaf edges fully of 1 cell layer or with 2-layer stretches, seldom entirely 2-layered, the submarginal cells sometimes thicker-walled and more deeply colored than the medial cells, forming a border; costa in X-section with distinguished ventral and dorsal superficial cells, a few guide cells (typically in 1 row), and ventral and dorsal stereid bands (FNA 2007).

Exposed or submerged rocks in rivers and creeks (Elliott & Pipp, 2016). Occurring from lowlands to about 6230 feet in elevation (FNA 2007).

Dioicous. Perigonia axillary, the bracts widely egg-shaped and cupped. Perichaetia terminal, the interior bracts half again as long as the outer bracts. Seta not as long as the capsule. Capsule becoming shiny and black with time, the theca compacting below when dry (FNA 2007), looking like a miniature, “thick rubber tire” (Flowers 1973), the longitudinally-ribbed columella then exserted above the capsule mouth and supporting the operculum to which it is attached (FNA 2007); peristome of 32 smooth, red teeth, curving outward when dry and inward when wet (Lawton 1971). Calyptra draping like a hood (FNA 2007).