Bryum violaceum Crundwell & Nyholm, Bot. Not. 116: 94. 1963

Plants small, green, yellow-green, often reddish. Stems0.4-1(-1.5) cm; rhizoids pale to bright violet, purple, or rarely red-purple. Leaves loosely set, ovate-lanceolate, weakly concave, 0.4-1(-1.5) mm; base not decurrent; margins plane to weakly revolute basally, entire to serrulate distally, limbidium absent; apex acute; costa short-excurrent, awn slender; alar cells similar to adjacent juxtacostal cells; proximal laminal cells abruptly quadrate to short-rectangular, 2-4:1; medial and distal cells (30-)40-60 × 8-14 µm, 3-4:1. Specialized asexual reproduction by rhizoidal tubers, on long rhizoids in soil, purple-red or rarely orange, irregularly spheric, 60-80(-100) µm, cells 25-30 µm, smooth. Sexual condition dioicous. [Capsule nutant, 1-3 mm].

Capsules mature Apr-Jul (spring-summer). Damp soil, soil over rock, disturbed sites; low to moderate elevations (0-1000 m); B.C., N.S., Ont., Que.; Ariz., Calif., Idaho, Mass., Mo., Nev., Utah, Wash., Wis.; s South America (Argentina, Chile); Eurasia; Atlantic Islands (Tenerife); Pacific Islands (New Zealand).

Gemmabryum violaceum is distinguished by the combination of violet rhizoids and small, spheric, red to purple-red or orange rhizoidal tubers. Gemmabryum ruderale is similar but has larger tubers, and European material at least has strongly papillose rhizoids compared to relatively smooth rhizoids of G. violaceum.