The parsnip (Pastinaca sativa) is a flowering plant in the family Apiaceae closely related to carrot and parsley. It is a biennial plant; in its first growing season, the plant has a rosette of pinnate, mid-green leaves, and in its second year, it produces a flowering stem topped by umbels of small yellow flowers in the summer, later producing pale brown, flat, winged seeds.
The parsnip is native to Eurasia, from Great Britain and Spain east to southern Siberia and Mongolia; Introduced to the Americas by European settlers, it has become a common weed in many areas. The foliage, flowers, and unripe fruit contain furanocoumarins that can sensitise mammalian tissue to sunlight and so cause photodermatitis in the form of a skin rash or even blisters; contact with the eyes can potentially cause blindness.
It is extensively cultivated as a root vegetable for its long taproot, which has light cream-coloured skin and flesh, and becomes sweeter in flavour after winter frosts; it is grown as an annual as if left in the ground to mature and flower, the stem becomes woody, and the taproot inedible. It has been used as a vegetable since antiquity and was cultivated by the Romans, although some confusion exists between parsnips and carrots in the literature of the time. It was used as a sweetener before the arrival of cane sugar in Europe. Parsnips are usually cooked but can also be eaten raw. The flesh has a sweet flavour, even more so than carrots. It is high in vitamins, antioxidants, and minerals (especially potassium); and also contains both soluble and insoluble dietary fibre. Parsnips are best cultivated in deep, stone-free soil. The plant is attacked by the carrot fly and other insect pests, as well as viruses and fungal diseases, of which canker is the most serious.
Description The parsnip is a biennial plant with a rosette of roughly hairy leaves that have a pungent odour when crushed. The plant's apical meristem 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 single-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 around tall. It is erect, but often slightly kinked at the leaf nodes, hairy, grooved, hollow (except at the nodes), and sparsely branched. Higher up the flowering stem, it has a few stalkless, single-lobed leaves measuring long that are arranged alternately, one at the base of each umbel stem.
The yellow flowers are in a loose, compound umbel measuring in diameter, with flowering (in Britain) in July to August. Six to 25 straight pedicels are present, each measuring that support the umbellets (secondary umbels). The umbels and umbellets have no or one to two basal bracts; when present, they are soon shed. The flowers have tiny sepals or lack them entirely, and measure 1.5–3.5 mm wide. They consist of five yellow petals that are curled inward, five stamens, and one pistil. The fruit is a schizocarp, oval and flat, with narrow wings and short, spreading styles. They are straw-coloured to light brown, and measure long.
Despite the slight morphological differences between the two, wild parsnip is the same taxon as the cultivated version, and the two readily cross-pollinate. The parsnip has a chromosome number of 2n=22.
Taxonomy
Pastinaca sativa was first officially described by Carolus Linnaeus in his 1753 work Species Plantarum. Two subspecies are currently accepted: Pastinaca sativa subsp. sativa — western and central Europe from Great Britain east to Slovakia and south to Spain and Italy. Pastinaca sativa subsp. urens (Req. ex Godr.) Čelak. — central, southern and eastern Europe east to Central Siberia and southwest Asia (Lebanon).
Subspecies urens is a larger plant, growing to 2 metres tall, with straighter (less kinked at the nodes) growth, and greyer hairs on the stem. The name urens, 'burning', refers to its stronger furanocoumarin content, increasing the risk of skin burns (as does its French name , "burning parsnip").
Some authors accept the wild parsnip (from which the cultivated subsp. sativa is derived) as a third subspecies Pastinaca sativa subsp. sylvestris (Mill.) Rouy & Camus, but these two are considered synonymous by the Plants of the World Online database. Some other authors treat the wild plant as subsp. sativa, but instead with the cultivated crop plant distinguished as P. s. var. hortensis.
It has acquired several additional synonyms in its taxonomic history: Pastinaca fleischmannii Hladnik, ex D.Dietr. Pastinaca opaca Bernh. ex Hornem. Pastinaca pratensis (Pers.) H.Mart. Pastinaca sylvestris Mill. Pastinaca teretiuscula Boiss. Pastinaca umbrosa Steven, ex DC. Pastinaca urens Req. ex Godr. Several species from other genera (Anethum, Elaphoboscum, Peucedanum, Selinum) are likewise synonymous with the name Pastinaca sativa.
Like most plants of agricultural importance, several other subspecies and varieties of P. sativa have been described, but these are mostly no longer accepted as independent taxa, but rather, minor variations of the same taxon. Pastinaca sativa subsp. divaricata (Desf.) Rouy & Camus Pastinaca sativa subsp. pratensis (Pers.) Čelak. Pastinaca sativa subsp. sylvestris (Mill.) Rouy & Camus Pastinaca sativa subsp. umbrosa (Steven, ex DC.) Bondar. ex O.N.Korovina Pastinaca sativa var. brevis Alef. Pastinaca sativa var. edulis DC. Pastinaca sativa var. hortensis Ehrh. ex Hoffm. Pastinaca sativa var. longa Alef. Pastinaca sativa var. pratensis Pers. Pastinaca sativa var. siamensis Roem. & Schult. ex Alef.
In Europe, various subspecies have been named based on characteristics such as the hairiness of the leaves, the extent to which the stems are angled or rounded, and the size and shape of the terminal umbel.
Etymology The etymology of the generic name Pastinaca (Latin for parsnips and carrots) is not known with certainty but is probably derived from either the Latin word , meaning 'to prepare the ground for planting of the vine' or , meaning 'food'. The specific epithet sativa literally means 'sown' or 'planted', but is used in botanical nomenclature to mean 'cultivated'.
The name comes from Middle English , alteration (influenced by , 'turnip') of Old French (now panais) from Latin pastinum, a kind of fork. The word's ending was changed to -nip by analogy with turnip because it was mistakenly assumed to be a kind of turnip.
Distribution and habitat The parsnip is native to Eurasia, from Great Britain and Spain east to southern Siberia and Mongolia. It typically occurs on dry, neutral to calcareous soils, in rough grassland or other low-growing uncultivated habitats like road verges and hedge sides. In Great Britain, it is widespread and often abundant throughout the lowlands of England and Wales, but more scattered in Scotland, where in is most frequent in the Central Lowlands; it generally occurs at low altitudes, up to a maximum of 380 m altitude. Its native distribution does not extend to Ireland, where it is an introduced neophyte.
Invasivity
The parsnip's popularity as a cultivated plant has led to its spread beyond its native range, and wild populations have become established in other parts of the world. Scattered populations can be found throughout North America, southern and western South America, southern Africa, and Tasmania.
The plant can form dense stands which outcompete native species and is especially common in abandoned gardens, farmland, and along roadsides and other disturbed environments. The increasing abundance of this plant is a concern, particularly due to the plant's toxicity and increasing abundance in populated areas such as parks. Control is often carried out via chemical means, with glyphosate-containing herbicides considered effective.
Cultivation Parsnips are grown for their fleshy, edible, cream-coloured taproots. The roots are generally smooth, although lateral roots sometimes form. Most are narrowly conical, but some cultivars have a more bulbous shape, which generally tends to be favoured by food processors as it is more resistant to breakage.
History Zohary and Hopf note that the archaeological evidence for the ancient cultivation of the parsnip is "still rather limited" and that Greek and Roman literary sources are a major source about its early use. They warn that "there are some difficulties in distinguishing between parsnip and carrot (which, in Roman times, were white or purple) in classical writings since both vegetables seem to have been called pastinaca in Latin, yet each vegetable appears to be well under cultivation in Roman times".
This plant was introduced to North America simultaneously by the French colonists in Canada and the British in the Thirteen Colonies for use as a root vegetable, but in the mid-19th century, it was replaced as the main source of starch by the potato and consequently was less widely cultivated.
In 1859, a new cultivar called 'Student' was developed by James Buckman at the Royal Agricultural College in England. He back-crossed cultivated plants to wild stock, aiming to demonstrate how native plants could be improved by selective breeding. This experiment was so successful 'Student' became the major variety in cultivation in the late 19th century.
Propagation The wild parsnip from which the modern cultivated varieties were derived is a plant of dry, rough grassland and waste places, particularly on chalk and limestone soils. Parsnips are biennials, but are normally grown as annuals. Sandy and loamy soils are preferable to silt, clay, and stony ground; the latter produces short, forked roots. Parsnip seed significantly deteriorates in viability if stored for long. Seeds are usually planted in early spring, as soon as the ground can be worked to a fine tilth, in the position where the plants are to grow. The growing plants are thinned and kept weed-free. Harvesting begins in late fall after the first frost and continues through winter. The rows can be covered with straw to enable the crop to be lifted during frosty weather. Low soil temperatures cause some of the starches stored in the roots to be converted into sugars, giving them a sweeter taste. Problems Parsnip leaves are sometimes tunnelled by the larvae of the celery fly (Euleia heraclei). Irregular, pale brown passages can be seen between the upper and lower surfaces of the leaves. The effects are most serious on young plants, as whole leaves may shrivel and die. Treatment is by removing affected leaflets, whole leaves, or by chemical means.
The crop can be attacked by larvae of the carrot fly (Chamaepsila rosae). This pest feeds on the outer layers of the root, burrowing its way inside later in the season. Seedlings may be killed while larger roots are spoiled. The damage done provides a point of entry for fungal rots and canker. The smell of bruised tissue attracts the fly.
Parsnip is used as a food plant by the larvae of some lepidopteran species, including the parsnip swallowtail (Papilio polyxenes), the common swift moth (Korscheltellus lupulina), the garden dart moth (Euxoa nigricans), and the ghost moth (Hepialus humuli). The larvae of the parsnip moth (Depressaria radiella), native to Europe and accidentally introduced to North America in the mid-1800s, construct their webs on the umbels, feeding on flowers and partially developed seeds.