Rapistrum

About

Rapistrum, the bastard cabbages, is a genus of the family Brassicaceae with a distinctive cross like arrangement of its petals. It is also known as wild-turnip or turnipweed. Species of Rapistrum are annual to perennials. The yellow petals are accompanied by sepals that stand vertically at near right angles (erecto-patent). Leaf shape and arrangement varies from rough toothed (dentate) to a configuration of opposingly lobed pairs along the plant stalk, pinnately lobed.

Summary from Wikipedia