Brachymenium spirifolium (C. Müll.) Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1873–74: 119. 1875.
Bryum spirifolium C. Müll., Linnaea 38: 623. 1874. Protologue: Mexico. Ad arborum radices ad ripas fluminis Rio blanco prope Orizaba, inter Bryum subcapillifolium vigens: C. Mohr 1857.
Plants medium-sized, bright-green to yellowish green above, reddish at base, in dense, shiny tufts. Stems to 15 mm long, epidermal cells rectangular, densely tomentose at base; rhizoids reddish brown, papillose. Leaves in crowded, rosulate tufts, 2–3 mm long, erect-flexuose, spirally contorted when dry, spreading when wet, concave, elongate-oblong; apices short acuminate, ending in a smooth or toothed, hyaline to yellow hair-point; margins bordered below by 2–3 rows of linear, thick-walled cells, entire below, obscurely and finely serrulate above, plane above, narrowly revolute below; costa yellowish, tapering to apex, long-excurrent, ventral superficial cells at base quadrate to rectangular; cells firm-walled throughout, upper cells hexagonal, 30–50 x 14–18 μm, basal cells long-rectangular, 30–60 x 20 μm. Dioicous. Setae 15–25 mm long, red. Capsules 3–4 mm long, cylindrical, constricted at neck, erect to suberect; opercula 0.5–0.75 mm long, high-conic and obliquely beaked; annuli compound, revoluble; exostome teeth linear, separate at base, reddish yellow below, whitish above, densely papillose, endostome whitish, papillose, basal membrane to ½ the exostome teeth length, segments rudimentary to moderately developed, linear, with narrow perforation gaps, cilia rudimentary to absent. Spores 30–40 μm, oblong, lightly papillose. Calyptrae 3 mm long, cucullate, yellow, smooth.