Raphanus raphanistrum, Brassicaceae
Here pictured is a yellow-flowered wild radish, often confused with yellow mustard (Sinapis alba, in the same family), growing on the banks of the river Clyde, in Glasgow, and naturalised in many areas of the world. At first sight, looking at the flowers and leaves, I actually thought this was yellow mustard myself, but the peculiar siliquae, which narrow visibly in the space between the seeds, made me think twice.
It turned out that, although wild radish flowers generally range in shade from white to purple, with evident darker veins, there are areas where the yellow-flowered variation is the most common. The seed capsule seem to confirm my guess too and I’ve kept some for propagation. Going by subspecies things can get harder as members of the genus hybridise easily and intermediate plants can be quite ambiguous. Due to the flower colour and seed capsules, the one above looks more like R. raphanistrum ssp. landra, the Italian wild radish, than R. raphanistrum ssp. raphanistrum, the English wild radish, although I’m in Scotland.
Because of the similar, but smaller edible taproot, R. raphanistrum is sometimes quoted as the ancestor of radish, R. sativus, domesticated in Europe before Roman times. Looking for more information on the subject I found a research paper about the ancestry of cultivated radish. The results are interesting and seem to suggest radish, Italian wild radish and English wild radish are the closest related members of the genus, with the Italian variety being more closely related to radish than the English one. Further speculation suggests that R. sativus could descend from a third variety historically present in the eastern Mediterranean, where the species had started spreading to Europe from Asia.
Today I’ve learnt a lot about radish, who would’ve known!
Here’s a short read about R. sativus hybridisation with wild species from the American Journal of Botany.
