Stem leaves patent to erect-spreading, concave, lamina 1-stratose through-out; proximal leaves minute and bract-like, long-deltoid, subulate, 0.38-0.8 × 0.15-0.23 mm, entire proximally, minimally serrulate to entire distally; distal stem leaves with oblong-ovate base, apex subulate, 1.03-2.13 × 0.18-0.35 mm, entire proximally, infrequently serrulate distally; costa narrow, percurrent. Perichaetial leaves oblong-ovate, gradually narrowed to long-subulate, frequently crisped awn, 2.25-3.43 × 0.23-0.4 mm, margins entire proximally, irregularly serrate to serrulate distally in the subula; basal cells loosely rectangular; median cells irregular, subquadrate to short-rectangular to rhomboidal; distal cells in subula oblong to trapezoidal; costa percurrent, filling the tubulose subula; transverse section of costa at mid leaf with central guide cells forming a row across the width between a more restricted band of adaxial stereids and an extensive abaxial stereid band, accessory cells sandwiched in the center; innermost perichaetial leaves ovate, more or less sheathing base and acuminate tip, subpercurrent. Specialized asexual reproduction absent. Sexual condition autoicous, antheridia naked in persistent axillary leafy buds, one to several along the distal part of stem. Seta 0.25-0.53 mm. Spores 25-31.3 µm, densely and finely papillose, light orange-brown in mass.
Tufts on wet sandy soil in roadside ditches and moist habitats; low to moderate elevations; B.C., N.B., N.S., Ont., Que.; Ala., Ark., Calif., Conn., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., Nebr., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., S.C., Tenn., Vt., Va., Wash., W.Va., Wis.; West Indies (Puerto Rico); Europe.
The chromosome number of Pleuridium subulatum is n = 13 (V. S. Bryan 1956; H. A. Crum and L. E. Anderson 1981; A. J. E. Smith and M. E. Newton 1968). It and P. acuminatum are morphologically similar. Pleuridium subulatum is distinguished by its autoicous sexual condition and 1-stratose lamina at leaf shoulder.