Introduced perennial grass to 6m tall. Leaves with a sheath at the base. Ligule a fringe of hairs. Leaves 60-200cm long, 3-20mm wide, folded in bud, then flat, slightly glaucous above, dark green below, hairless to hairy, rough, margins knife-sharp, with pointed tips. Spikelets silvery white to pink or mauve, 10-18mm long, fading to light brown or straw-coloured. Seeds very hairy, pointed, with 0 awns. Mature seed groups oval, at the tops of the stems.
PlantNET description with line drawing: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Cortaderia~selloana
ausgrass2 description with line drawing and photos: http://ausgrass2.myspecies.info/content/Cortaderia-selloana
Weeds of Australia Biosecurity Queensland Edition description: http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-0605030c0f01/media/Html/Cortaderia_selloana.htm