wild radish, (Raphanus raphanistrum), widespread annual plant of the mustard family (Brassicaceae), native to Eurasia. Wild radish has naturalized throughout much of the world and is a noxious agricultural weed in many places. The plant is believed by some authorities to be the ancestor of the domestic radish (Raphanus sativus), and the two species readily hybridize.
Wild radish has a stout taproot, a rosette of unequally divided leaves, and very bristly flowering stalks about 60 cm (2 feet) tall. The four-petaled flowers may be yellow, lilac, white, or violet and have visible veins. The fruits, borne below the flower head, are narrowly oval, jointed siliques containing 4 to 10 seeds.