Hoary Cress, White Weed, Hoary Pepperwort
Introduced perennial forb to 90cm tall, or sprawling. Leaves basal and alternating up the stems, hairy, margins toothed to entire. Basal leaves 2.5-10cm long, stem leaves stem clasping, to 7.5cm long. Flowers fragrant, with 4 white petals, in groups at the tops of the stems. Proclaimed weed SA. Noxious weed Vic.
Description and photo (as Cardaria draba) in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales pages 320-321
eFloraSA fact sheet (as Cardaria draba): http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&name=Cardaria_draba