Plants light- to yellowish-green, glossy, in dense tufts. Stems to 80 × 1--1.5 mm, erect, julaceous. Leaves closely imbricate, smooth, concave, symmetric, 1.5--2.5 × 0.8--1.2 mm, ovate or oblong-ovate, acuminate, apex usually recurved, margins broadly recurved throughout, entire or denticulate near apices; costa short and double, one branch sometimes reaching 1/3 length of leaf; leaf cells smooth, walls of basal cells pitted; median cells 85--141 × 6--12 μm; decurrent alar region triangular or rarely somewhat oval in outline, consisting of 2--4 vertical rows of rectangular or inflated, oval cells, 40--60 × 9--24 μm, terminating at the base in a single cell. Specialized asexual reproduction unknown. Sexual condition and sporophyte unknown.

Swales, wet tundra and rocky slopes and cliffs; 0--1220 m; Greenland; N.W.T.; Alaska; Europe (Norway).

This is an Arctic species that has been confused with P. cavifolium, or julaceous forms of P. laetum and P. denticulatum. The acuminate leaves with recurved apices will separate P. berggrenianum from P. denticulatum, while the inflated, oval cells in the decurrencies will distinguish it from P. cavifolium and P. laetum.