What is "rapistrum"

Rapistrum, the bastardcabbages, is a genus belonging to the Brassicaceae family with a distinctive cross like arrangement of its petals. Species of Rapistrum are annual to perennials (Lifespan from 1 to 2 or more years). 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.