Origin:
Native to Europe, and now widespread in North America. The garden variety of radish is a cultivated form of wild radish. R. sativus is white-flowered, while R. raphanistrum is yellow-flowered.
Biology:
These are winter or summer annual, and under the proper growing conditions may be biennials. They reproduce only from seeds, and seeds are capable of germinating in either early spring or early autumn. Those seeds that germinate in the fall produce rosettes of leaves at the ground level, and these rosettes over-winter.
Identification:
Plants begin as a rosette of large, deeply divided leaves. Mature plants can be as tall as 5 feet, and are heavily branched toward the top of the plant, off of the main stem. Leaves vary widely in size and shape, with lower leaves deeply divided into leaflets and upper leaves being smaller and either undivided or with small lobes. The surfaces of the leaves are coarse and covered with bent, bristly hairs. There is a stout taproot that has a radish-like taste and odor. Flowers are yellow on raphanistrum, and on sativus range from white to pink to purple. They form as single flowers on pedicels arranged along the elongating stems. Seed pods develop below the flowers, and as they mature they become swollen and spongy, and up to 3 inches long, tapering to a long point or beak. The pods do not open, but instead break off as segments containing the seeds.
Characteristicts Important to Control:
A winter annual reproducing only from seed. Physical removal of individual plants is successful, but the strong taproot resists pulling.
