Introduced annual or short lived perennial grass to 50cm tall, often mat-forming. Leaves with a hairless sheath at the base. Ligule a membrane without a rim of hairs. Leaves folded lengthwise or flat, 0.5-14cm long, 1-5mm wide, hairless to slightly rough, with slightly rough edges and blunt or pointed tips. Spikelets green, reddish, or purplish, 3-10mm long. Seeds with 0 bristles. Mature seed heads cylindrical to spreading.
Description and photo in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales page 133
PlantNET description with line drawings and photo of dried plants: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Poa~annua
ausgrass2 description with line drawings and photo: http://ausgrass2.myspecies.info/content/poa-annua