About Raphanus raphanistrum L.
Wild radish, scientifically named Raphanus raphanistrum L., is an annual plant that grows up to 75 centimetres (30 in) tall. It can be variously branched or multi-stemmed, and has a distinct slender taproot that does not swell like the taproot of cultivated radish. Its stems are green, sometimes purple at the base and nodes, round in cross section, slightly ridged, and covered all over with bristly hairs. It produces a basal rosette of pinnate leaves that reach up to 38 cm (15 in) long; each leaf has a 3-cm petiole (leaf stalk) and a large rounded terminal lobe with an undulate margin, and the lateral lobes sometimes overlap the midrib. Stem leaves become progressively less lobed as they grow up the stem, and develop more acutely serrated edges. Both the upper and lower surfaces of every leaf are roughly hairy, as are the leaf margins, which have minutely bulbous-based hairs that project horizontally. Each tooth on the leaf margin has a green or purple-tipped hydathode. Its flowering period runs from May to October in northern Europe, and from June to August in Minnesota. The inflorescence is a lax raceme, which grows terminally or from a leaf axil, reaching up to 34 cm long and holding up to 42 flowers. The flowers have four petals, which are most often white (sometimes yellow or purple), and grow up to 24 mm long; petals sometimes have dark veins, especially on their underside. Each petal has a rounded "limb" above a narrow "claw", and the two parts are roughly the same length. The four upright sepals are shorter than the petals, green or purple, and bear sparse bulbous-based hairs. There are 6 stamens (2 short and 4 long) and one style with two stigmas. The fruits grow on bristly-hairy pedicels about 3 cm long, and are held vertically whether the inflorescence rhachis is erect or sprawling. Each fruit is a pod divided into two segments: the lower segment is about 1-2 mm long and sterile, only occasionally producing a single seed, while the upper segment grows up to 8 cm long and holds 1–10 fertile segments called mericarps, each containing one oval seed up to 3 mm long. At the tip of the pod is a sterile beak up to 2.5 cm long. The fruits are terete, smooth or slightly ridged, and range from glabrous to roughly hairy, with a peppery taste. A persistent, sessile white stigma remains at the tip of the beak. It is native to temperate regions of North Africa, Europe, and parts of Western Asia. Its confirmed distribution includes North Africa (Macaronesia, the Madeira Islands, the Canary Islands, Algeria, Egypt, Libya, Morocco, and Tunisia); Western Asia (the Caucasus, Armenia, Azerbaijan, Cyprus, Georgia, Iran, Iraq, Israel, Jordan, Lebanon, Syria, and Turkey); Eastern Europe (Belarus, Moldova, and Ukraine); Middle Europe (Austria, Belgium, the Czech Republic, Germany, Hungary, the Netherlands, Poland, Slovakia, and Switzerland); Northern Europe (Denmark, Estonia, Finland, Ireland, the Isle of Man, Latvia, Lithuania, Norway, Sweden, and the United Kingdom); Southeastern Europe (Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Italy, Montenegro, North Macedonia, Romania, Serbia, and Slovenia); and Southwestern Europe (France, Portugal, and Spain). It is frost hardy, and even hard freezes only temporarily interrupt its blooming. In Australia, it is considered an invasive species that threatens native habitats in many areas. In Canada, it is a naturalised species that sometimes hybridizes with cultivated radish, R. sativus. It has also developed resistance to several herbicides. In southeastern USA, the pale yellow form of the plant is common, sometimes entirely taking over winter fields. It is a significant source of pollen and nectar for a variety of pollinators, especially for honey bees during their very early spring population buildup. Female Andrena agilissima mining bees frequently visit this plant to collect pollen and nectar. Other pollinators include cabbage butterflies and a small number of syrphid fly species. All tender parts of the plant are edible. The leaves and flowers have a spicy taste or aftertaste. The seedpods can be eaten, as can the outer skin of the root after washing. As early as 1753, John Walker discovered the plant on the west coast of Scotland, and cultivated its root as an alternative to horseradish.
