Pale Knotweed, Pink Knotweed
Annual forb to 1.8m tall. Leaves with a sheath at the base, alternating up the stems, 6-21cm long, 10-60mm wide, flat, hairless to hairy, gland-dotted and sticky, midribs and edges hairy or rough. Flowers often small (less than 3mm across), pink, with 4-5 'petals', in dense oval to cylindrical spikes on stalks arising from the bases of the leaves, with 2 or more spikes forming panicles at the ends of the stems.
Description and photos (as Polygonum lapathifolium) in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales page 232