Montana Field Guide

Plants: Acrocarpous (Vitt 19881). Growing in open to somewhat congested clumps or frequently large areas (FNA 2007) and lawns (Vitt 1988) of tall shoots, deep green, becoming brown over time, developing from a subterranean rhizome. Stems upright or prostrate with the ends ascending (FNA 2007), seldom branching (Crum & Anderson et al. 1981), usually 5-10 cm long, but occasionally up to 70 cm, with rhizomes at the base (FNA 2007).

Leaves: With a sheath below and a blade above, the sheath with smooth, transparent margins, and distinct joint-tissue where blade and sheath meet. Leaves closely to somewhat distantly spaced on the stem, upright or spreading a little when dry, spreading widely or the blade severely bent back from its base ca 90 degrees (FNA 2007), 6-10 mm in length (Crum & Anderson et al. 1981), the glossy, frequently golden sheath (FNA 2007) 2-3 mm in length (Crum & Anderson et al. 1981), tubular and enveloping the stem, constricted at the joint to meet the slender, lance-shaped blade; margins of the lamina flat or upright (“holding in” the lamellae), dentate from the bottom of the blade to the leaf tip (FNA 2007); lamellae 21-55, obscuring almost all of the leaf blade (Crum & Anderson et al. 1981); costa extending beyond the apex and toothed dorsally close to the leaf tip; costal awn short and coarse (FNA 2007).

Leaf Cells: Marginal lamina usually 2-3 cells in width, seldom to 7 cells, the cells nearly square, the teeth along the blade each consisting of 1 cell rooted in the margin; lamellae 5-9 cells tall, in X-section each topmost (marginal) cell retuse so that looking from above, a lengthwise groove runs along the top of each rib, the marginal cells usually larger and broader than the cells beneath, but occasionally narrow, brown, with somewhat thick walls; sheath cells quadrangular, long and narrow, sometimes 20:1, thinner near the margins (FNA 2007).

Polytrichum commune var. commune: Present in Montana.
Plants, although variable, typically tall and sturdy; stems, including extremes, from 2-70 cm; leaves somewhat closely to distantly spaced, the blade margins with sharp teeth to the joint; topmost cells of the lamellae wider than those below, deeply retuse in X-section, the knobs noticeably protruding, the groove deep (FNA 2007).

Polytrichum commune var. perigoniale:
Plants growing in congested tufts; stems to 6 cm tall; leaves closely spaced and tightly overlapping, ribbon-like, contorted when dry; the marginal teeth not as sharp as in var. commune; topmost cells of the lamellae narrow and only shallowly retuse, the groove therefore shallow (FNA 2007).

Variety commune: Damp organic soil in wet areas, meadows, swamp and bog edges, commonly overlying large stretches; common in boreal forest (FNA 2007).

Variety perigoniale: Humus and damp soil, uncrowded woodlands, along roads (FNA 2007).

Dioicous. Perichaetial leaves with a long sheath, the sheath margins membranous, and the blade much smaller than those of the vegetative leaves; apex acuminate; margins finely toothed to almost entire; costa excurrent. Seta russet to yellow, 5-9 cm tall. Capsule like a square or slightly elongated block, russet to brown, with a waxy bloom when young, 3-6 mm in length, level to somewhat upwardly sloping, with 4 longitudinal wings (FNA 2007), the theca 2.5-5.5 mm in length, ca 2 mm in width (Lawton 1971), very narrowly constricted above an evident neck (Crum & Anderson et al. 1981); peristome teeth 64. Calyptra totally encasing the capsule, golden to brown (FNA 2007), thickly hairy (Vitt 1988).

Variety commune: Interior perichaetial leaves scarcely longer than the vegetative leaves, the awn short with minute, sharp teeth (FNA 2007).

Variety perigoniale: Interior perichaetial leaves longer than the vegetative leaves, slowly narrowing to an almost silky, long awn (FNA 2007).