Montana Field Guide

Plants: Acrocarpous, growing in open tufts, light- to deep-green, frequently touched with red (Crum and Anderson et al. 1981). Stems turning russet to deep red with time, 1-5 cm in height; rhizoids brown (FNA 2014), with macronemata frequently woolly and matted at leaf axils and branch attachments (Crum and Anderson et al. 1981); micronemata lacking (FNA 2014).

Leaves: Remote except near the stem apices, upright to spreading, twisted, curved or bent when dry, spreading (Crum and Anderson et al. 1981) and typically flat or occasionally slightly wavy when damp, 2-7 mm in length, widest in the middle to widely obovate, ending in a curved leaf tip, occasionally obtuse or squared, forming a short apiculus or mucro; margins light green or occasionally somewhat red, flat, smooth; costa reaching the apex or nearly so, the upper part of the dorsal face smooth (FNA 2014).

Leaf Cells: Margins 2 to 4 cell-layers in thickness; marginal cells distinct, long to short, thin, in 3-4 series; medial laminal cells somewhat long to only slightly elongate, porose, with or without slightly thickened wall angles (FNA 2014); distal cells erratically 6-sided or appearing oblong with 6 sides, sometimes slightly elongated and in diagonal rows, porose, occasionally with wall angles thickened (Crum and Anderson et al. 1981); alar cells not distinct from adjacent cells (FNA 2014); costa in X-section appearing convex on both surfaces, without stereid bands (Flowers 1973).

Fruit ripens in spring (FNA 2014).

A key characteristic for distinguishing Rhizomnium species is the presence or absence of micronemata on older stems. New growth often lacks micronemata, so checking and comparing mature stems, which may be covered with litter, is necessary (FNA 2014).

Wet soil, humus, rotten wood, and stones in seepy areas close to springs and swampy, high-nutrient, evergreen woods (Crum and Anderson et al. 1981), protected bluffs. From lowlands to medium elevations (FNA 2014).

Dioicous. Seta solitary (FNA 2014) or seldom 2 (Crum and Anderson et al. 1981), 15-35 mm tall. Capsule 2-3.5 mm in length (FNA 2014), level to drooping, somewhat yellow or brown; stomata entirely sunken in the neck area (Crum and Anderson et al. 1981); exostome teeth 16, yellow with green tones (FNA 2014) or somewhat ochre; endostome with cilia in 2s or 3s (Crum and Anderson et al. 1981). Calyptra draped like a monk’s hood (FNA 2014).

Specialized vegetative reproduction from green macronemata (FNA 2014). When separated from the stem, the macronemata may produce protonemata (Crum and Anderson et al. 1981).