In taxonomy botanical names are always associated with their types.
The image is of Portulaca grandiflora Hook.
See the protologue and lectotype (Illustration) of this species attached here.
Flowers of Portulaca oleracea L. is yellow. Frequently found as weed in cultivation and wastelands. Eaten as pot herb and used for medicinal purposes also. See the lectotype specimen at Linnaean Herbarium (LINN-HL625-1).
http://linnean-online.org/6248/
Leaves alternate or sometimes subopposite; leaf blade 8-38 × 4-18 mm, flat, obovate, apex obtuse, retuse, rounded or truncate; base cuneate. Flowers in clusters of 3-7, 4-6 mm across, surrounded by involucre of 2-6 bracts. Sepals green, 3.5-4.5 mm long, apex acute, keeled. Petals 5, 3-5 mm long, yellow, obovate, apex retuse, slightly connate at base.