1. Clasmatodon parvulus (Hampe) Sullivant in A. Gray, Manual ed. 2. 660. 1856.
Leskea parvula Hampe, Linnaea 13: 46. 1839; Clasmatodon parvulus var. rupestris Lesquereux & James
Plants slender, in interwoven mats. Stems to 1(-2) cm, branches to 2(-5) mm, erect; axillary hair distal cell obtuse, pale brown. Stem leaves ± subsecund, 0.3-0.5 mm wide; laminal cells 18-30 × 8-10 µm, smooth. Seta0.2-0.5 cm. Capsule 0.7-1 mm; annulus 3- or 4-seriate, cells small, brown; exostome teeth blunt, partially connate; endostome basal membrane inconspicuous, segments 16, short, slender, unequally 2-fid, partially fused to basal membrane. Spores finely roughened.
Tree trunks and bases, flood plain forests, calcareous rock; low to moderate elevations (0-400 m); Ala., Ark., Fl., Ga., Ill., Ind., Ky., La., Md., Miss., Mo., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W. Va.; Europe.
The inconspicuous plants of Clasmatodon parvulus form small, slender, straggly mats on tree trunks in southeastern North America north of Mexico. The species is characterized by a short costa (Leskea species have a strong costa ending near the apex), ovate, mostly bluntly acute leaves (Lindbergia has long-acuminate leaves), and a lack of erect, flagelliform branchlets (as in Platygyrium repens). The elliptic, erect capsules with a reduced peristome on short setae also are diagnostic.