Plants gregarious or forming a thin turf, green distally, tan proximally. Stems to 0.4[-3] cm, branching occasionally; rounded-pentagonal in transverse section, hyalodermis absent, sclerodermis present as substereids, central strand present or absent; rhizoids few; axillary hairs of ca. 5(-10) cells, the basal 1-2 brownish. Leaves appressed-incurved when dry, weakly spreading reflexed when moist; narrowly ligulate or rectangular to long-ovate, adaxial surface nearly flat, 0.25-1.4 mm; base scarcely differentiated to ovate [sheathing]; distal margins plane to weakly recurved, entire, 1-stratose [2-stratose]; apex rounded to rounded acute or obtuse, sometimes apiculate by a sharp cell; costa ending ca. 4[-8] cells below apex [percurrent], adaxial outgrowths absent, adaxial cells elongate in 2-8 rows, abaxial cells elongate; transverse section of costa semicircular to ovate, adaxial epidermis usually present, adaxial stereid band absent or weak, exposed, guide cells 2 in 1 layer, hydroid strand absent, abaxial stereid band present, crescentiform or round in sectional shape, abaxial epidermis present or commonly absent; basal cells differentiated across leaf base in proximal ¹/4-¹/2 of leaf, little wider than distal cells or somewhat bulging [inflated], 3-5:1, walls of basal cells thin to evenly thickened; distal medial cells quadrate or shortly rectangular, ca. 8-11 µm wide, 1(-2):1, papillae absent or hollow, simple to indistinctly 2-fid, cell walls thin to evenly thickened, superficially flat to convex. Specialized asexual reproduction when present by oval to spindle-shaped gemmae, of several cells, borne on basal rhizoids, green or brown. Sexual condition dioicous [autoicous, occasionally heteroicous]; perigonia appear as buds at plant base or terminal, gemmate; perichaetia terminal, inner leaves often strongly sheathing seta, lanceolate, to 1.5 mm, laminal cells often rectangular to rhomboid. Seta yellow-brown, ca. 1.5-3[-6] mm, twisted clockwise. Capsule yellow-brown, ovate to short-cylindric, [neck differentiated,] 0.8-1 mm, exothecial cells shortly rectangular to rhomboid, thin-walled, annulus of 2-3 rows of highly vesiculose cells, revoluble and deciduous in pieces; operculum short-conic [narrowly rostrate], ca. 0.2-0.3[-0.6] mm, cells in straight rows; peristome teeth absent [16, rudimentary, short, spreading, ligulate or oblong and highly perforate, straight, articulations ca. 3-

Gyroweisia species have ligulate leaves with subpercurrent costae and enlarged, hyaline basal cells, a vesiculose annulus, and peristome absent or rudimentary peristome. Gyroweisia differs from the similar Gymnostomum by the occasional presence of a rudimentary peristome (outside the flora area), the large annulus, sterile plants distinctly smaller than the sporophyte-bearing gametophytes, basal leaf cells differentiated more strongly (often in the basal ¹/4 to ¹/2), and the more common presence of gemmae.