Plants: 0.1–1.2 cm. Stem: leaves contorted when dry, wide-spreading and distinctly 3-ranked when moist, ovate-lanceolate, 1.5–4 mm; base decurrent; margins plane to weakly reflexed proximally, serrulate distally; apex acute; costa narrow, ending in or just before apex; inner laminal cells smaller, walls thicker than marginal cells. Sexual: condition dioicous. Seta: 3–10 cm. Capsule: 3–4.5 mm. Spores: 33–38 µm.
Rich fens, arctic and boreal areas. moderate to high elevations. Greenland, Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon, Alaska, Calif., Mich., Minn., Mont., Nebr., N.J., N.Y., Oreg., S.Dak., Vt., n Eurasia.
Meesia triquetra is frequent where appropriate habitat is available, and disjunct in a few locations farther south. The species is usually easily distinguished by its three-ranked, widely spreading leaves that have serrulate margins. The sexual condition is dioicous.