Plants with shoots 20 30 ´ 2.4 3 mm, prostrate, forming mats over peat or occurring as stems intermingled with moss, pure green to yellowish or reddish brown. Stems ca. 10 12 cells in diameter, branches few, most arising beneath perianths; cortical cells 28 35 µm in diameter, slightly smaller than medullary (32 42 µm); interior cells with small trigones. Leaves contiguous to imbricate, spreading to erect, orbicular to ovate, ca. 1400 ´ 1450 µm, narrowed at the insertion, concave; leaves on gemmiparous shoots progressively narrower toward stem apex, becoming lanceolate (ca. 1400 1500 ´ 1100 1150 µm) with subacute apex; median leaf cells large, 50 60 ´ 45 50 µm, basal cells larger, 50 55 ´ 65 75 µm; cuticle smooth; trigones large, bulging, knotlike; oil bodies 6 18 per cell, ovoid, 7 8 ´ 5 7 µm, granular botryoidal with protruding globules, hyaline. Underleaves distinct, lanceolate, large (to 500 600 µm), often hidden among rhizoids. Specialized asexual propagation by gemmae, often present on distal lanceolate leaf margins, spherical to elliptical, 30 40 ´ 45 50 µm, 2 celled, green. Androecia intercalary; bracts 4 7 pairs, entire, ovate with saccate base, antheridia 1 2 per bract. Gynoecia terminal on main shoot; bracts similar to leaves, larger, somewhat recurved; bracteole large, lanceolate; perianth inflated, compressed laterally, exerted above bracts about 1/2 its length; mouth 2-labiate, entire to slightly crenulate.

Peat bogs or on moist peaty soil over outcrops, Arctic alpine; s, sw and w Greenland; Alta, B.C., Nfld., N.W.T., N.S., Ont., Que., Yukon; Alaska, Conn., Maine, Mich., Minn., N.H., N.J., N.Y., Pa., Wash., W.Va., Wis.; n Europe; e Asia.

Commonly found in northern Sphagnum bogs, this species occurs as far south as the Cranberry Glades of West Virginia.