Soursob; Soursop; Bermuda Buttercup
Introduced perennial forb to 45cm tall. Leaves basal, each composed of three leaflets each 0.5-3cm long, 3.5-40mm wide, flat, hairless to sparsely hairy, with sparsely hairy edges and a notched apex. Flowers yellow, with 5 petals fused together at their bases, in umbels of 3-25 flowers, on stalks arising from the base of the plant. Flowers open only in sunny conditions. Declared plant in SA. Noxious weed in Vic.
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 pages 435-436
Weeds of Australia Biosecurity Queensland Edition description: http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-0605030c0f01/media/Html/Oxalis_pes-caprae.htm