Montana Field Guide

Plants: Acrocarpous (Vitt 1988) Growing in clumps of erect shoots or patches, green with yellow or grey tones, or deep brown with black (FNA 2007), usually appearing hoary from the hyaline hair-points (Crum & Anderson et al. 1981). Stems occasionally over 15 cm, sometimes with rhizoids near the bottom (FNA 2007), typically with many tuft-like branches (Lawton 1971); lacking a central strand (FNA 2007).

Leaves: Closely spaced on the stem, upright and flat against the stem when dry, spreading slightly when moist, straight to curved and pointing in one direction, 3-5 mm in length, 0.6-0.9 mm in width, lance-shaped with linear tendencies; margins curved back and under or tightly rolled back for a little over half the leaf length, smooth below; apex slowly narrowing to a thin, long (FNA 2007) [laminal] hair-point (awn); hair-point to 2 mm in length (Lawton 1971), transparent, covered with papillae, decurrent along the margins about 1/4 to 1/3 of the leaf length, the decurrencies also transparent, raggedly toothed to smooth, spreading 40-90 degrees (FNA 2007); costa vanishing into the hair-point (Lawton 1971).

Leaf Cells: Costa in X-section quadrangular to kidney-shaped in profile, very rounded dorsally (FNA 2007); margins 1 cell-layer thick (Lawton 1971); upper laminal cells quadrangular and short; medial laminal cells elongate to linear, wavy and knobby; proximal laminal cells quadrangular, long, porose, and very knobby, with 1 or 2 rows of nonsinuose cells appearing as an orange band across the leaf attachment; alar cells not distinguished (FNA 2007).

No other acrocarpous moss is known to have papillose setae (FNA 2007).

The papillae of the laminal cells are identical in R. lanuginosum and Codriophorus species. However, Codriophorus species lack hair-points on their leaves (FNA 2007).

Usually dry and open habitats (although moisture levels can vary), usually on acidic (seldom calciferous) soil, stones, bluffs, talus slopes, tundra, peat hillocks, edges of bogs (FNA 2007), and barren, treeless mountaintops (Crum & Anderson et al. 1981). Elevation: 0-7550 feet (FNA 2007).

Dioicous. Fruit uncommon. Seta 3-10 mm tall, spiraled counterclockwise when dry, papillose, brown, up to 3 setae per perichaetium (FNA 2007), often paired (Crum & Anderson et al. 1981). Capsule 1-1.7 mm in length, brown and lustrous, extending beyond the perichaetia; peristome teeth 2-lobed, divided nearly to the bottom into thread-like sections, each thickly covered with tiny, sharp papillae (FNA 2007).