Perennial grass to 55cm tall. Leaves with a sheath at the base. Ligule a fringe of hairs. Leaves 7-14cm long, 1-5mm wide, flat or the edges rolled inwards, sticky hairy, rough, with pointed tips. Spikelets green when flowering, becoming black, then fading to pale straw-coloured when the seeds are mature, 4-5mm long. Seeds with 9 awns. Mature seed groups oval to cylindrical.
Description and photo (pages 95-96) and line drawing of seed and husks (Fig. 20e page 94) in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales. The description of the flowerhead 'becoming fluffy and grey, gradually turning black at maturity' is incorrect.
PlantNET description with line drawings and photo: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Enneapogon~nigricans
ausgrass2 description with photo: http://ausgrass2.myspecies.info/content/enneapogon-nigricans