Bryum squarrosum Hedwig, Sp. Musc. Frond., 186, plate 44, figs. 6-11. 1801

Plants 3-7 cm. Stem leaves stiff when dry or moist, 1.5-2 mm; margins serrulate distally; apex acute to short-acuminate; costa narrow, ending before apex. Sexual condition dioicous. Seta 2.5-4.5 cm. Capsule 2-3 mm. Spores 15-22 µm.

Calcareous wet fens; low to high elevations; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Colo., Iowa, Maine, Mich., Minn., Mont., N.Y., Vt.; n Eurasia.

Paludella squarrosa is one of the most spectacular moss species in the flora area. The squarrose-recurved leaves (more squarrose than in any other species, including Rhytidiadelphus squarrosus), combined with the calcareous wet fen habitat are all that is needed for identification.