The usually larger plants, distinctly prorate leaf cells and keeled leaves, that are generally folded lengthwise in micropreparations, will help to identify this species. South African specimens of P. laeviuscula Dix. have been included here, although more research into the relationship between the two species is needed. The specimens are somewhat larger in size and leaf length, the leaf cells are laxer and marginal cells larger. These modifications seem to be environmentally produced, and the specimens not distinct enough from P. falcata to recognize another species for the group. One of the syntypes of Bartramia squarrifolia (Moss s.n., PRE-CH9388) would fall into this group and is quite similar in size and structure to the type of P. laeviuscula.
Plants small to medium-sized, caespitose, green to yellow-green, brownish below; terrico lous or saxicolous. Stems 20-50(-80) mm high, branching by subperichaetial innovation, tomentose below, red-brown; in section round, central strand large, inner cortical cells in 2-3 rows, large, thin-walled, ± thickened toward outside, outer cortical cells in 2 rows, incrassate or substereids, yellow-brown, epidermal cells large, thin-walled, ± inflated, fragile. Leaves widespreading to squarrose, ± contorted dry or rarely incurved, widespreading wet, keeled; ovate-acuminate, (1.0-)1.2-1.5 mm long; margins plane, serrate above. Costa short-excurrent, ventral and dorsal superficial cells long-rectangular, prorate; in section bulging dorsally, guide cells 3-4, incrassate, ventral stereid or substereid band weak, occasionally absent, ventral surface cells incrassate, dorsal stereid band stronger, 2-4 cells thick, cells occasionally substereids, frequently with distinct gap below central guide cells, dorsal surface cells incrassate. Laminal cells rectangular, 1.5-3.0:1, generally weakly thickened, prorate ventrally at distal or proximal ends; basal cells rectangular, ± bulging, prorate except at insertion. Dioicous. Perigonia terminal; leaves broadly oval, abruptly narrow-acuminate. Perichaetia terminal, overgrown by numerous subperichaetial innovations; leaves oval to oblong, abruptly narrow-acuminate, to 2 mm long. Seta 25-35 mm long, red-yellow; capsule inclined to suberect, urn globose to ovoid, 2.5 mm long, weakly striate dry, red-yellow; exothecial cells hexagonal to rhomboidal or angular, thickened, 6 rows at capsule mouth transversely rectangular, reddish; stomata present at base of urn, phaneropore; peristome double, exostome teeth 16, narrowly triangular, fragile, finely papillose, endostome with segments alternating with teeth, perforated, cilia 2-3, ornately papillose; operculum not seen; spores subround, 27-30 µm, papillose, brownish.
Plants caespitose. Stems 20-80 mm long, tomentose below, in section with large central strand. Leaves contorted when dry, keeled, ovate-acuminate, 1.0-1.5 mm long; margins plane, serrate above; costa short-excurrent. Upper laminal cells rectangular, prorate at proximal ends; basal cells rectangular, prorate. Capsule inclined to suberect, globose to ovoid, weakly striate; peristome double, exostome teeth 16, fragile, endostome segments perforated, cilia 2 or 3. Spores subround, papillose.
Philonotis falcata is known from Asia, India and Africa. In southern Africa, the species is frequently collected in Natal and Lesotho, and occasionally found in South West Africa/Namibia, Botswana, the Transvaal, Zululand, Transkei and the eastern, central and southwestern Cape.