Plants small, in dense to lax, yellowish to yellowish green tufts, tomentose proximally. Stems simple, erect to inclined, straight or curved, 0.5--1.5(--3) cm. Leaves triangular-lanceolate, 0.7--1.3 mm, erect and straight or curved and homomallous when dry, erect-spreading when moist; margins plane proximally, narrowly revolute distally, serrulate nearly to base, teeth paired distally, usually single proximally; costa percurrent to short-excurrent, rough abaxially distally; laminal cells prorulose at distal ends, distal cells narrowly oblong, 20--50 × 5--8 µm, basal cells wider, quadrate to rectangular, 10--65 × 8--12 µm. Specialized asexual reproduction by brood branches in the axils of distal leaves. Sexual condition dioicous; perigonia gemmiform. Seta erect, 1.3--3 cm. Capsule ovoid, 1.5--2 mm. Spores subspherical to reniform, 23--26 µm, papillose.

Capsules mature Feb.--Mar. Rocks and soil in open habitats; 0--30 m; Ala., Fla., Ga., Ky., La., Miss., S.C., Tex.; Mexico; West Indies; Central America; n and c South America; Pacific Islands.

This species, restricted in the flora area largely to states bordering the Gulf of Mexico, is recognized by the diminutive habit, the percurrent to short-excurrent costa, doubly toothed leaf margin and laminal cells prorulose at distal ends. Philonotis glaucescens, treated as a synonym here, has been recognized elsewhere as P. uncinata var. glaucescens (Hornschuch) Florschütz (P. A. Florschütz 1964) or as P. glaucescens (Hornschuch) Brotherus (Crum and Anderson 1981). The features on which "P. glaucescens" is recognized (whether as a variety or as a species) - straight leaves and a percurrent costa - would seem to fall well within the universe of variation displayed by P. uncinata, the oldest name available for this group of related forms.