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The parsnip (''Pastinaca sativa'') is a root vegetable closely related to the carrot and parsley. It is a biennial plant usually grown as an annual. Its long tuberous root has cream-colored skin and flesh and can be left in the ground when mature as it becomes sweeter in flavor after winter frosts. In its first growing season, the plant has a rosette of pinnate, mid-green leaves. If unharvested, it produces its flowering stem, topped by an umbel of small yellow flowers, in its second growing season. By this time the stem is woody and the tuber inedible. The seeds are pale brown, flat and winged. The parsnip is native to Eurasia. It has been used as a vegetable since antiquity and was cultivated by the Romans, although there is some confusion in the literature of the time between parsnips and carrots. It was used as a sweetener before the arrival in Europe of cane sugar. It was introduced into the United States in the nineteenth century. The parsnip is usually cooked but can also be eaten raw. It is high in vitamins and minerals, especially potassium. It also contains antioxidants and both soluble and insoluble dietary fiber. It can be cultivated in deep, stone-free soils. It is attacked by the carrot fly and other insect pests, viruses and fungal diseases, of which canker is the most serious. Handling the stems and foliage can cause a skin rash if the skin is exposed to sunlight after handling. ==Description== The parsnip is a biennial plant with a rosette of roughly hairy leaves that has a pungent odor when crushed. Parsnips are grown for their fleshy, edible cream-colored taproots. The roots are generally smooth, although lateral roots sometimes form. Most are cylindrical, but some cultivars have a more bulbous shape, which generally tend to be favored by food processors as they are more resistant to breakage. The plant has an apical meristem that produces a rosette of pinnate leaves, each with several pairs of leaflets with toothed margins. The lower leaves have short stems, the upper ones are stemless, and the terminal leaves have three lobes. The leaves are once- or twice-pinnate with broad, ovate, sometimes lobed leaflets with toothed margins; they grow up to long. The petioles are grooved and have sheathed bases. The floral stem develops in the second year and can grow to more than tall. It is hairy, grooved, hollow (except at the nodes), and sparsely branched. It has a few stalkless, single-lobed leaves measuring long that are arranged in opposite pairs.〔Rubatsky ''et al''. (1999), pp. 30–31.〕 The yellow flowers are in a loose, compound umbel measuring in diameter. There are 6–25 straight pedicels, each measuring that support the umbellets (secondary umbels). The umbels and umbellets usually have no upper or lower bracts. The flowers have tiny sepals or lack them entirely, and measure about . They consist of five yellow petals that are curled inward, five stamens, and one pistil. The fruits, or schizocarps, are oval and flat, with narrow wings and short, spreading styles. They are colored straw to light brown, and measure long.〔Cain ''et al''. (2010), p. 218.〕 Despite the slight morphological differences between the two, wild parsnip is the same taxon as the cultivated version, and the two will readily cross-pollinate.〔 Parsnip has a chromosome number of 2''n''=22.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「parsnip」の詳細全文を読む スポンサード リンク
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