Hedge Mustard, Indian Hedge Mustard, Wild Mustard
Introduced annual or biennial forb to 1.3m tall. Basal leaves not persisting, to 11cm long, flat, hairy, lobed. Stem leaves flat, hairy, edges entire or lobed. Flowers yellow, with 4 petals, in groups at the tops of the stems, which elongate as the fruiting bodies mature.
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 335. Differences between species of Sisymbrium are detailed under Sisymbrium altissimum page 333.
FloraBase photos: http://florabase.dpaw.wa.gov.au/browse/photo/3072