Plants medium-sized, green, yellow-green or brownish, never red; branch and shoot apices not pencil-like; cells of stem epidermis not widened; pseudoparaphyllia ovate-triangular to lanceolate (rarely broader); axillary hairs with 1--3-celled distal portion, hyaline when young. Stem leaves almost straight or slightly falcate (rarely more strongly falcate), narrowly ovate-triangular or ovate, gradually narrowed to acuminate or often obtuse or blunt point, leaf apex often hooked (incurved over leaf), concave; margins ± entire or finely denticulate; costa ending 65--80% distally in leaf; alar cells in usually indistinctly delimited isodiametric or, more rarely, transversely triangular group, not decurrent, supra-alar cells often large and then together with alar cells often forming an oval or rectangular group along lower leaf margins. Sexual condition autoicous.

Mineral-poor and acid habitats, apparently favored by disturbance, slightly sloping poor fens, ditches or periodically water-filled depressions; 0--1220 m; Greenland; B.C., Nfld., Ont.; Alaska, Minn., Wash., Wyo.; Europe.

Warnstorfia pseudostraminea is usually readily recognizable in the field, where it gives an impression of an intermediate between W. fluitans and Straminergon stramineum. It could be confused with W. fluitans or green plants of W. exannulata, and the distinguishing characters of these species are given in their respective discussion. The genus Calliergidium, in which W. pseudostraminea was sometimes placed is discussed under Drepanocladus. Warnstorfia pseudostraminea is widespread in lowlands of northern Europe, and it seems likely that this is the case also in North America.