Plants typically small and slender, sometimes compact in Arctic forms, capitulum small with a conspicuous terminal bud; green to yellowish brown; without metallic lustre when dry. Stems pale green to straw-colored; superficial cortical with a large round pore in distal portion of cell free from cell wall. Stem leaves broad-spatulate, 0.8--1.5(--2) mm, strongly lacerate across the broad apex and part way down the margins, border scarcely to moderately broadened at base (0.25 width of base or less); hyaline cells rhomboidal, efibrillose and often 1--2-septate. Branches not 5-ranked, quite terete, long, and slender Branch fascicles with 2 spreading and 1--2 pendent branches. Branch leaves ovate to ovate-lanceolate; 1.1--1.5(--2) mm, slightly concave, straight; apex involute; margins entire; hyaline cells on convex surface with numerous pores along the commissures grading from small pores near leaf apex to large pores at base, concave surface with large round pores at leaf apex and along margins. Sexual condition monoicous. Spores 20--27 µm, finely papillose on both surfaces; proximal laesura less than 0.5 spore radius.

Capsules mature late spring and early summer. Minerotrophic, common at the mineral soil margins of bogs and poor fens, medium open and forested fens; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., Que., Sask., Yukon; Alaska, Cal., Colo., Conn., Del., Idaho, Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mont., Mo., N.H., N.J., N.Y., Ohio, Oreg., Pa., R.I., Tenn., Vt., Wash., Wis., W.Va.; South America; Eurasia; Pacific Islands (New Zealand).

Sporophytes are very common. This species is associated with Sphagnum centrale, S., fallax, S. henryense, S. affine, S. palustre, S. russowii, S. teres, S. warnstorfii, and Drepanocladus exannulatus. It is normally a very easily recognizable species because of its very small size, pale green color, and distinct terminal bud. In Alaska it overlaps with S. concinnum, which has a similarly very broad and lacerate stem leaf apex but, in that species, the lacerate margin does not extend down the sides of the leaf. Sphagnum concinnum is also a more compact-growing species with a distinctly browner color.