Perennial herbs, caespitose, occasionally very shortly rhizomatous. Culms numerous, rigid, terete or compressed, with or without nodes. Leaf-sheaths tightly encircling culm bases, dull or shining, yellow-brown often turning red-brown or grey-brown with age, in some species breaking up with age to form a network of fibres; ligule membranous or chartaceous; leaf-blades reduced, or long, rigid, channelled, pungent-pointed. Inflorescence capitate, hemispherical, globose or narrow fan-shaped, occasionally reduced to a single spikelet, subtended by 1–3 long rigid involucral bracts with enlarged dark bases that envelop the inflorescence at least when immature. Spikelets oblong-lanceolate, compressed, sessile, usually producing only one nut, but a second flower usually apparently bisexual; glumes 5–10 (the lowest 3–8 empty), distichous, carinate, oblong-lanceolate, brown to black with the bases paler, produced in a straight to excurved awn often as long as the body of the glume. Rachilla short, straight. Hypogynous scales 3, similar, brown to black above, paler below, finely antrorsely scabrous above, at first slender, at maturity very much broadened at the base and loosely enclosing the nut, abruptly acuminate and twisted above. Stamens 3; anthers linear, yellow, with the connective produced in a long subulate appendage. Style long, 3-fid, antrorsely scabrous, not persistent on the nut. Nutlet dry, indehiscent, glabrous, ovate or oblong-ovate, trigonous with very obtuse angles, base broad, apex obtuse; in most species seated on a thickened, cup-shaped gynophore with or without a spreading 3-lobed disc at the top.
Generally on sandy soils in various heath formations. One species, Mesomelaena preissii, is found on the more inland lateritic sandplains while the rest are more or less restricted to coastal sandplains, with extensions into the Darling and Stirling Ranges. Mesomelaena graciliceps usually grows in low-lying and at least seasonally swampy areas, while the other species are found in drier habitats.
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