Thuidium glaucinum var. ludovicianum Cardot

Plants light green or yellow. Stems 3-6 cm, irregularly to regularly 2-pinnate, loosely foliate; paraphyllia papillose at sides of cells. Stem leaves loosely erect or slightly incurved when dry, erect-spreading when moist, ovate, not or somewhat plicate, 1 mm; margins plane or sometimes reflexed basally, ± denticulate throughout by projecting cell ends; apex broadly short-pointed, acute; costa ending near apex; distal laminal cells hexagonal, 7 × 7 µm, . Branch leaves with apical cell truncate, multipapillose. Primary branch leaves 0.5-0.6 mm; costa 8/10-9/10 leaf length. Secondary branch leaves 0.2-0.4 mm; apex acute or obtuse; costa 7/10 -8/10 leaf length. Sporophytes unknown.

Capsule maturity unknown. Soil, logs, exposed roots, tree bases in swamps, just above water line, Taxodium-Nyssa-Chamaecyparis swamps; low to moderate elevations; Ala., Ark., Conn., Del., Fla., Ga., Ind., La., Md., Mass., Miss., N.Y., N.C., Pa., Tenn., Tex., Va.

Thuidium alleniorum is essentially restricted to the Atlantic and Gulf coastal plains and the Mississippi Embayment. The species is slender and loosely, sometimes irregularly 2-pinnate. Thuidium alleniorum could easily be taken for a depauperate expression of T. delicatulum. However, T. alleniorum is smaller and has short-pointed stem leaves with margins plane or nearly so, and the branch leaves are noticeably incurved. The laminal cells are 8-9 µm and adorned with very low papillae that are generally 2-fid so that the cells commonly appear in surface view to be 2 (or 3)-papillose.