The unusual rigid ranking of the leaves up the stem, and shape of leaves and leaf cells should place specimens of C. pentastichum. The southern African plants are at the lower limits of measurements published for New Zealand plants where stems reach 40 mm high and the seta and capsules are 10-35 mm and 1.5-3.5 mm long, respectively.
Plants small to medium-sized, forming dense cushions, yellow-brown to yellow-green, brownish below; terricolous or saxicolous. Stems 5-10(-15) mm tall, irregularly branched, tomentum dense on lower stem, red-brown; in section subround to angular, central strand small, inner cortical cells in 3 rows, large, thin-walled, outer cortical cells in 2 rows, thickened or substereids, red-yellow, epidermal cells large, thin-walled, fragile, stem becoming fluted. Leaves crowded, erect-appressed in 5 distinct rows wet or dry; narrowly triangular to oblong-lanceolate, 1.0-1.2 mm long, lamina bistratose juxtacostally from base; cells with strongly thickened adjoining walls, outer walls thin, bulging, 4-8 rows at margin unistratose, cells rounded, ± evenly thickened; apex acute, toothed; margins plane below, weakly reflexed above, entire, serrate near apex. Costa short-excurrent as smooth awn, 0.2-0.3 mm long, ventral superficial cells rectangular, weakly prorate and ± thickened near apex, dorsal superficial cells rectangular, strongly prorate at distal ends and ± thickened near apex; in section guide cells not well defined, ±6, substereids, ventral cells in single layer continuous with upper layer of lamina, cells enlarged, inner walls strongly thickened, outer walls very thin-walled, dorsal substereid band 2 cells thick, dorsal surface cells continuous with lower layer of lamina, similar to ventral surface cells. Upper laminal cells rhomboidal to fusiform or narrow-rectangular, 7-10:1, becoming weakly thickened and distally prorate above, slightly narrower toward margin; basal cells rectangular, 2-5:1, thin-walled, smooth. Perigonia terminal on branches, leaves elliptical, yellowish; costa short-excurrent. Perichaetia terminal, leaves similar to vegetative leaves or slightly broader; laminal cells narrow, thin-walled. Seta 3-4 mm long, flexuose, yellow-brown; capsule suberect, urn oval-orbicular wet, elliptical and sulcate dry, 1.5 mm long, red-brown; exothecial cells hexagonal to oblong-hexagonal, 2 rows smaller and quadrate at mouth; stomata present at base of urn, phaneropore; peristome single, fragile, red-yellow, teeth 16, linear, smooth, joined at apex; operculum obliquely rostrate; calyptra not seen; spores oval-reniform, 50-60 µm, reddish brown, with low, bulging, ± hexagonal plates covering distal surface.