Plants less than 2.5 mm, scattered in sparse protonemata. Leaves lanceolate, broadly linear or ligulate, acuminate, sometimes narrowed distally from shoulders, 0.8--2.5 ´ 0.15--0.4 mm; margins serrulate or serrate, with teeth sometimes recurved up to 45°; apex acuminate and papillose; costa at the base thin or not always apparent, stronger distally, often filling the acumen, percurrent or excurrent, papillose; areolation firm proximally and distally compact to dense; median laminal cells in + vertical rows, smooth or slightly papillose; distal laminal cells papillose. Capsule with columella resorbed before meiosis; stomates in proximal half or scattered throughout. Spores various, 43 ´ 35 to 120 ´ 80 µm

Varieties 2 (2 in the flora): North America, Europe.

Lower Taxa

• Ephemerum crassinervium var. crassinervium
• Ephemerum crassinervium var. texanum (Grout) V. S. Bryan & L. E. Anderson

Related Synonym(s):

• Ephemerum crassinervium var. papillosum (Austin) Renauld & Cardot = Ephemerum crassinervium var. crassinervium
• Ephemerum spinulosum var. texanum Grout = Ephemerum crassinervium var. texanum (Grout) V. S. Bryan & L. E. Anderson
• Phascum crassinervium Schwägrichen = Ephemerum crassinervium var. crassinervium