Plants small, delicate, in lax to dense tufts, bright green. Stems 0.5-1 cm, erect, simple to sparingly branched; proximal rhizoids absent or weakly developed. Leaves erect to incurved when dry, erect-spreading to spreading when moist, ovate-oblong to ligulate or ovate-lanceolate to ovate, 0.3-1 mm; margins revolute throughout or revolute proximally and plane distally, bluntly serrulate, teeth paired; apex broadly acute to rounded-obtuse; costa 7/8 leaf length or subpercurrent, distal abaxial surface rough; laminal cells obscurely to clearly prorulose at distal ends; basal cells rectangular, 25-35 × 10-15 µm; distal cells subquadrate to oblong rhomboidal, 20-30 × 10-12 µm. Specialized asexual reproduction by occasional short brood branches in distal leaf axils. Sexual condition dioicous; perigonia gemmate. Sporophytes unknown.

Moist, rocky, limey soil, rock crevices; low to moderate elevations (0-1500 m); Ala., Fla., Kans., La., Miss., N.C., Okla., Tex.; Mexico; West Indies; Central America; South America.

P. A. Florschütz (1964) treated Philonotis gracillima as a variety of P. uncinata. Philonotis gracillima is distinguished in the flora area by the combination of a broad leaf apex (both broadly acute and rounded-obtuse apices may occur on the same plant), relatively short costa, and lax, pellucid laminal cells.