Rhytidiadelphus triquetrus var. beringianus (Cardot & Thériot) Grout
Plants robust, coarse and shaggy, 3--8 mm wide measured across leafy stem, to 20 cm long. Stems irregularly branched to unevenly pinnately branched; branches commonly to 25 mm, often arcuate-decurved. Stem leaves wide-spreading, pointing in all directions, crowded at stem tip, ovate-triangular, plicate, rugose, 3.2--4.9 × 1.6--2.5 mm; base cordate-clasping, broadly rounded to the insertion; apex evenly tapered to a broad, flat (occasionally rugose) acumen; costa extending 1/2--2/3 leaf; median cells 30--55 × 5--9 µm, coarsely prorate; alar cells only slightly differentiated from basal cells. Branch leaves ovate to lanceolate, 1.8--3.1 × 0.7--1.6 mm. Capsule oblong-cylindric, 1.8--3.5 mm.
Soil and humus, less often on logs and rock, in a variety of forests from dry-mesic oak/hickory to wet Thuja swamps, most common in northern coniferous forests; 0--2000 m; Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ariz., Ark., Calif., Conn., Idaho, Ill., Ind., Iowa, Maine, Md., Mass., Mich., Minn., Mo., Mont., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., S.Dak., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo.; Eurasia; Pacific Islands (New Zealand).
A specimen of Rhytidiadelphus triquetrus from Florida in the Torrey Herbarium (NY) is correctly identified, but the locality is very unlikely.