Plants annual; cespitose. Culms 20-120 cm, erect to decumbent, often rooting at the lower nodes, branching above the bases. Leaves not aromatic; sheaths open; auricles absent; ligules membranous, ciliate. Inflorescences terminal and axillary, solitary, 2-sided rames, these sometimes fascicled and partially enclosed in subtending leaf sheaths at maturity; disarticulation in the rames, beneath the sessile spikelets. Spikelets in heterogamous sessile-pedicellate pairs. Sessile spikelets hemispherical, partly embedded in the rame axes; lower glumes as long as the spikelets, indurate, alveolate, indistinctly 7-11-veined, not keeled, margins involute; upper glumes chartaceous, 3-veined, usually adherent to the rame axes; lower florets sterile; upper florets bisexual; anthers 3. Pedicels adnate to the rame axes, concealed by the sessile spikelets. Pedicellate spikelets as long as or longer than the sessile spikelets, ovate; lower glumes dorsally compressed, 5-9-veined; upper glumes laterally compressed, 5-7-veined; lower florets sterile; upper florets staminate; anthers 3. x = 7 (probably). Named for Eduard Hackel (1850-1926), an Austrian agrostologist, and the Greek chloa, grass.