2. Thuidium recognitum (Hedwig) Lindberg, Not. Sallsk. Fauna Fl. Fenn. Förh. 13: 416. 1874. (as Thuyidium).
Hypnum recognitum Hedwig, Sp. Musc. Frond., 261. 1801; H. protensum Michaux
Plants light green to yellowish or brownish. Stems 4-9 cm, 2-pinnate, frondose; paraphyllia papillose usually at or near cell ends. Stem leaves ± incurved basally and wide-spreading apically when dry, spreading with reflexed apices when moist, broadly ovate, distinctly plicate, 1 mm; margins plane at least when removed from stem, rarely ± revolute proximally, papillose-serrulate, more strongly so in acumen; apex abruptly acuminate; costa nearly filling acumen but disappearing near apex; distal laminal cells rhombic to oblong-rhombic, to 24 × 8-10 µm. Branch leaves with apical cell truncate, multipapillose. Primary branch leaves to 0.5 mm; costa shorter. Secondary branch leaves 0.2 mm; apex acute; costa 1/3 -2/3 leaf length. Perichaetial leaves to 4.2 mm, margins denticulate, sometimes dentate or notched near base of acumen. Seta 2-4.2 cm. Capsule 2-3.5 mm; operculum 0.7-1 mm, long-conic or bluntly short-rostrate; endostome cilia in groups of 2 or 3. Spores 11-16 µm, smooth or nearly so.
Capsules mature fall-winter. Moist soil, humus, rock, logs, bark at base of trees, calcareous habitats, woodlands, clearings, timber trails; low to high elevations; Alta., B.C., Man., Ont., Que.; Alaska, D.C., Ga., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., Ohio, Okla., Oreg., Pa., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo.; Europe.
The specific epithet of Thuidium recognitum was applied by Hedwig because he recognized the many differences that separate the species from T. delicatulum: stem leaves that are shortly, broadly, and abruptly acuminate and plicate, with margins plane or nearly so; costa spreading out and nearly filling the acumen; stem leaf apices wide-spreading from an arched and incurved base; perichaetial leaves eciliate; paraphyllia papillose at or near cell ends; and operculum not or only shortly and bluntly rostrate. The secondary branch leaves of T. recognitum are erect-spreading when dry or moist and have rhombic distal laminal cells, 8-12 × 8-10 µm, that are thick-walled and stoutly 1-papillose with papillae somewhat curved.