Montana Field Guide

Plants: Acrocarpous. Growing in open clumps of erect shoots, shiny, pale green. Stems 0.4-1.5 dm tall; rhizoids thickly covering the stem in reddish or nearly white woolly matting (FNA 2007).

Leaves: Upright (FNA 2007) or typically spreading to widely so; very crumpled or wavy crosswise to the leaf (FNA 2007; Vitt 1988), a little bent and twisted, similar in wet and dry conditions, 5.5-10.5 mm in length, 1-2 mm in width, lance-shaped, cupped, keeled distally (FNA 2007) and a little pleated below (Lawton 1971); leaf edges strongly dentate above, folded up and inward a little proximally (Lawton 1971); costa subpercurrent, with 2 dorsal crests of teeth above (FNA 2007) reaching from ca mid-leaf to the apex (Lawton 1971).

Leaf Cells: Lamina 1 cell-layer thick, the cells smooth, and the walls between cells not bulging; upper laminal cells wavy and porose; lower laminal cells longer than those distally, porose; alar cells distinct, inflated, not reaching the costa, the alar region 2 cell-layers thick; costa in X-section with guide cells in 1 row, ventral and dorsal stereid bands (FNA 2007) in the lower part of the leaf (Lawton 1971), the ventral superficial cells not distinct, the dorsal epidermal layer with a few cells larger than the adjacent stereids (FNA 2007).

Fruit ripens in spring (FNA 2007).

One of largest Dicranum species, its branches appear thick from the numerous rhizoids. It also stands out with its broadly spreading, very wavy leaves with the conspicuous teeth above, and the aggregate of sporophytes (FNA 2007).

The similar Dicranum undulatum lacks ridges on its dorsal costal surface whereas D. polysetum has two ridges. Also, D. undulatum is found more often in organic soils of fens and bogs; D. polysetum is more characteristic of upland, northern coniferous forests of the mountains (Vitt 1988), and only occasionally in bogs (Lawton 1971).

Soil or (frequently) humus overlying stone, rotting wood (FNA 2007), sometimes bogs (Lawton 1971); coniferous woods, less frequently deciduous forests. Elevation: 30-6890 feet (FNA 2007).

Small males growing on female plant rhizoids. Inner perichaetial bracts enveloping the stem, suddenly narrowing to the long acumen. Seta typically 3-6 in a perichaetium, somewhat russet in color, 15-40 mm tall. Capsule bowed, tilted to level, grooved when dry, yellow with red or brown tones, 2-3.5 mm in length; peristome of 16 teeth, separated ca halfway down into 2 lobes (seldom 3), russet, with papillae above. Calyptra hood-like, hairless, sheltering much of the capsule, falling away easily (FNA 2007).