Sago Pondweed, Fennel Pondweed
Submerged perennial forb, stems to 3m long. Leaves alternating up the stems, with a sheath at the base, grass-like. Leaves 1.5-17cm long, to 2mm wide, linear, hairless, margins entire, tips pointed. Flowers small (less than 3mm across), with 4 'petals', in globular clusters of 2-6 flowers arranged along flowering the stems, forming interrupted spikes. Stuckenia pectinata in NSW and Vic.
Description, line drawings, 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 39
PlantNET description with line drawing of leaf base and photos of dried plants: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Stuckenia~pectinata