4. Taxiphyllum taxirameum (Mitten) M. Fleischer, Musc. Buitenzorg. 4: 1435. 1923.
Stereodon taxirameus Mitten, J. Proc. Linn. Soc., Bot., suppl.: 105. 1859; Isopterygium geophilum (Austin) A. Jaeger; I. taxirameum (Mitten) A. Jaeger; Plagiothecium geophilum (Austin) Grout; Rhynchostegium geophilum Austin; Taxiphyllum geophilum (Austin) M. Fleischer
Plants in thin to dense mats, dark green to yellowish. Stems 6 cm, 2-4 mm wide, complanate-foliate; rarely radiculose ventrally. Leaves wide-spreading to squarrose, usually distant, ovate- or oblong-lanceolate, rarely narrowly ovate, symmetric or nearly so, flat or somewhat concave, 1-2 × 0.3-0.6 mm; margins very narrowly recurved almost to apex, sometimes plane, serrulate throughout; apex acuminate or abruptly narrowed to acute or rarely subobtuse, not twisted; costa double and short or ecostate; alar cells few, long- to short-rectangular, rarely quadrate, 37-63 × 5-9 µm, in 1-3 rows, 1-5 cells in marginal row; laminal cells smooth or prorulose at distal ends on abaxial surface; medial cells 66-120 × 3-7µm. Seta reddish, 0.7-1.2 cm. Capsule reddish, oblong-ovoid, arcuate, 1-1.5 mm; operculum 0.5-1 mm. Spores 11-13 µm.
Capsules mature spring-summer. Shaded siliceous or calcareous soil and rock; low to moderate elevations (40-1500 m); Ala., Ariz., Ark., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Miss., Mo., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W. Va.; Mexico; West Indies; Central America; South America; se Asia.
Taxiphyllum taxirameum is a polymorphic species common in the southeastern and south-central United States, particularly the Ozark Mountain region. Taxiphyllum taxirameum has often been confused with the more northern 3. T. deplanatum; for distinctions, see the discussion under that species. Taxiphyllum taxirameum is the most common species of Taxiphyllum in Latin America, and it is especially prevalent in parts of Mexico and the West Indies.