野萝卜种

分布与习性

野芥菜原产于亚洲（亦有指原产于地中海，但被带到世界各地），但由于其极强侵入性的特质，这种植物目前在澳大利亚蔓延，经常都在路旁或其他荒废地被发现，被当地政府归为要消除的入侵物种。

这种植物亦有在美国东南部生产，花色通常都是淡黄色，在冬季有时会遍布整个田野。由于其外貌与芥辣很相似，所以经常被误认。野芥菜是花粉传播物种的重要花粉来源，特别是在冬季时的西方蜜蜂。

野萝卜是一种一年生或两年生的植物。

Raphanus raphanistrum, also known as wild radish, white charlock or jointed charlock, is a flowering plant in the family Brassicaceae. The species is native to western Asia, Europe and parts of Northern Africa. It has been introduced into most parts of the world and is regarded as a habitat threatening invasive species in many areas, for example, Australia. It spreads rapidly and is often found growing on roadsides or in other places where the ground has been disturbed. The cultivated radish, widely used as a root vegetable, is sometimes considered to be one of its subspecies as Raphanus raphanistrum subsp. sativus.

Description

Wild radish is an annual that grows up to 75 centimetres (30 in) tall, variously branched to multi-stemmed, with a distinct slender taproot which does not swell like that of the cultivated radish. The stems are green and sometimes purple at the base and nodes, round in cross section and slightly ridged, and bristly-hairy all over. It has a basal rosette of pinnate leaves to 38 cm (15 in) long, with a 3-cm stalk (petiole) and a large rounded terminal lobe that has a undulate margin; the lateral lobes sometimes overlap the midrib. The stem leaves become progressively less lobed as they ascend, and more acutely serrated. Both the upper and lower surface of each leaf is roughly hairy, as are the leaf margins, which have minutely bulbous-based hairs projecting horizontally. The leaves have green or purple tips (hydathodes) on each tooth.

Taxonomy

It was formally described by the Swedish botanist Carl Linnaeus in his seminal publication Species Plantarum in 1753.

The genome of wild radish is estimated to be ~515 Mb in size, whereas that of the edible variety is suggested to be ~539–574 Mb. Several Raphanus raphanistrum genomes have been sequenced, with one study reporting 98% coverage of the gene space. Researchers found evidence that the past whole-genome triplication that occurred before the divergence of Raphanus and Brassica has been followed by widespread gene loss in radish, resulting in the loss of ~38,000 genes from the wild radish genome.

Raphanus raphanistrum has several known subspecies including:

Raphanus raphanistrum subsp. landra (Moretti ex DC.) Bonnier & Layens ('sea radish')

Raphanus raphanistrum subsp. rostratus (DC.) Thell.

Raphanus raphanistrum subsp. sativus (L.) Domin

Distribution and habitat

It is native to temperate regions of North Africa, Europe and parts of Western Asia.

Range

It is found in North Africa, within Macaronesia, Madeira Islands, Canary Islands, Algeria, Egypt, Libya, Morocco and Tunisia. Within Western Asia it is found in the Caucasus, Armenia, Azerbaijan, Cyprus, Georgia, Iran, Iraq, Israel, Jordan, Lebanon, Syria and Turkey. In eastern Europe, it is found within Belarus, Moldova and Ukraine. In middle Europe, it is in Austria, Belgium, Czech Republic, Germany, Hungary, Netherlands, Poland, Slovakia and Switzerland. In northern Europe, in Denmark, Estonia, Finland, Ireland, Isle of Man, Latvia, Lithuania, Norway, Sweden and United Kingdom. In southeastern Europe, within Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Italy, Montenegro, North Macedonia, Romania, Serbia and Slovenia. Also in southwestern Europe, it is found in France, Portugal and Spain.

Ecology

It is frost hardy, and even hard freezes only temporarily interrupt bloom. In Australia, it is regarded as a habitat threatening invasive species in many areas. In Canada, it is a naturalised species and sometimes hybridizes with cultivated radish, R. sativus. It has also proved to be resistant to several herbicides.

In southeastern USA, the pale yellow form is common, sometimes entirely taking over fields in wintertime. It is a significant source of pollen and nectar for a variety of pollinators, especially honey bees during the very early spring starting buildup. Female Andrena agilissima, or mining bees, frequent this plant to obtain pollen and nectar. Other pollinators include cabbage butterflies and a few syrphid fly species.

Uses

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 being washed). It is said that John Walker cultivated sea radish root as an alternative to horseradish after discovering the plant on the west coast of Scotland as early as 1753.