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Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of '' Rheum'' in the family Polygonaceae, which are cooked and used for food. The whole plant – a herbaceous perennial growing from short, thick
rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
s – is also called rhubarb. Historically, different plants have been called "rhubarb" in English. The large, triangular
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
contain high levels of
oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...
and
anthrone Anthrone is a tricyclic aromatic ketone. It is used for a common cellulose assay and in the colorimetric determination of carbohydrates. Derivatives of anthrone are used in pharmacy as laxative. They stimulate the motion of the colon and reduce w ...
glycosides, making them inedible. The small flowers are grouped in large compound leafy greenish-white to rose-red inflorescences. The precise origin of culinary rhubarb is unknown. The species '' Rheum rhabarbarum'' (syn. ''R. undulatum'') and '' R. rhaponticum'' were grown in Europe before the 18th century and used for medicinal purposes. By the early 18th century, these two species and a possible
hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...
of unknown origin, ''R.'' × ''hybridum'', were grown as vegetable crops in England and Scandinavia. They readily hybridize, and culinary rhubarb was developed by selecting open-pollinated seed, so its precise origin is almost impossible to determine. In appearance, samples of culinary rhubarb vary on a continuum between ''R. rhaponticum'' and ''R. rhabarbarum''. However, modern rhubarb cultivars are tetraploids with 2''n'' = 44, in contrast to 2''n'' = 22 for the wild species. Although rhubarb is a vegetable, it is often put to the same culinary uses as fruits. The leaf stalks can be used raw, when they have a crisp texture (similar to celery, although it is in a different family), but are most commonly cooked with sugar and used in pies, crumbles and other desserts. They have a strong, tart taste. Many cultivars have been developed for human consumption, most of which are recognised as ''Rheum'' × ''hybridum'' by the Royal Horticultural Society.


Etymology

The word ''rhubarb'' is likely to have derived in the 14th century from the Old French , which came from the Latin and Greek , meaning 'foreign rhubarb'. The Greek physician Dioscorides used the Greek word (), whereas Galen later used (), Latin . These in turn derive from a Persian name for species of ''Rheum''. The specific epithet ''rhaponticum'', applying to one of the presumed parents of the cultivated plant, means 'rha from the region of the Black Sea' or the river Volga, Rha being its ancient name.


Cultivation

Rhubarb is grown widely, and with
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of Transparent ceramics, transparent material, such as glass, in which plants requiring regulated climatic condit ...
production it is available throughout much of the year. It needs rainfall and an annual cold period of up to 7-9 weeks at 3°C (37°F), known as ‘cold units’, to grow well. The plant develops a substantial underground storage organ (rhubarb crowns) and this can be used for early production by transferring field-grown crowns to warm conditions. Rhubarb grown in hothouses (heated greenhouses) is called "hothouse rhubarb", and is typically made available at consumer markets in early spring, before outdoor cultivated rhubarb is available. Hothouse rhubarb is usually brighter red, tenderer and sweeter-tasting than outdoor rhubarb.Rombauer, Irma S. (1975) ''Joy of Cooking''. Indianapolis/New York: Bobbs-Merrill Co., Inc. p. 142. After forcing for commercial production, the crowns are usually discarded. In temperate climates, rhubarb is one of the first food plants
harvest Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-i ...
ed, usually in mid- to late spring (April or May in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, October or November in the Southern Hemisphere), and the season for field-grown plants lasts until the end of summer. In the United Kingdom, the first rhubarb of the year is harvested by candlelight in forcing sheds where all other light is excluded, a practice that produces a sweeter, more tender stalk.McGee, Harold (2004). '' On Food and Cooking''. New York, NY: Scribner. p 367. These sheds are dotted around the " Rhubarb Triangle" between Wakefield, Leeds, and Morley. In the United states rhubarb is primarily produced in the states of Oregon, Washington, and Wisconsin with approximately 1,200 acres in production of which 175 are covered in hothouses. In the northwestern US states of Oregon and Washington, there are typically two harvests, from late April to May and from late June into July; half of all US commercial production is in
Pierce County, Washington Pierce County is a county in the U.S. state of Washington. As of the 2020 census, the population was 921,130, up from 795,225 in 2010, making it the second-most populous county in Washington, behind King County, and the 60th-most populous ...
. Rhubarb is ready to consume as soon as harvested, and freshly cut stalks are firm and glossy. Rhubarb damaged by severe cold should not be eaten, as it may be high in
oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...
, which migrates from the leaves and can cause illness. The colour of rhubarb stalks can vary from the commonly associated crimson red, through speckled light pink, to simply light green. Rhubarb stalks are poetically described as "crimson stalks". The colour results from the presence of
anthocyanin Anthocyanins (), also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart gave the name Anthokyan to a chemical compo ...
s, and varies according to both rhubarb variety and production technique. The colour is not related to its suitability for cooking.


Historical cultivation

The Chinese call rhubarb "the great yellow" ( ), and have used rhubarb root for medicinal purposes. It appears in '' The Divine Farmer's Herb-Root Classic'', which is thought to have been compiled about 1,800 years ago. Though
Dioscurides Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of ''De materia medica'' (, On Medical Material) —a 5-vol ...
' description of or indicates that a medicinal root brought to Greece from beyond the
Bosphorus The Bosporus Strait (; grc, Βόσπορος ; tr, İstanbul Boğazı 'Istanbul strait', colloquially ''Boğaz'') or Bosphorus Strait is a natural strait and an internationally significant waterway located in Istanbul in northwestern Tu ...
may have been rhubarb, commerce in the plant did not become securely established until Islamic times. During Islamic times, it was imported along the
Silk Road The Silk Road () was a network of Eurasian trade routes active from the second century BCE until the mid-15th century. Spanning over 6,400 kilometers (4,000 miles), it played a central role in facilitating economic, cultural, political, and reli ...
, reaching Europe in the 14th century through the ports of
Aleppo )), is an adjective which means "white-colored mixed with black". , motto = , image_map = , mapsize = , map_caption = , image_map1 = ...
and Smyrna, where it became known as "Turkish rhubarb". Later, it also started arriving via the new maritime routes, or overland through Russia. The "Russian rhubarb" was the most valued, probably because of the rhubarb-specific quality control system maintained by the Russian Empire. The cost of transportation across Asia made rhubarb expensive in medieval Europe. It was several times the price of other valuable herbs and spices such as
cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...
,
opium Opium (or poppy tears, scientific name: ''Lachryma papaveris'') is dried latex obtained from the seed capsules of the opium poppy ''Papaver somniferum''. Approximately 12 percent of opium is made up of the analgesic alkaloid morphine, which i ...
, and saffron. The merchant explorer
Marco Polo Marco Polo (, , ; 8 January 1324) was a Venetian merchant, explorer and writer who travelled through Asia along the Silk Road between 1271 and 1295. His travels are recorded in ''The Travels of Marco Polo'' (also known as ''Book of the Marv ...
therefore searched for the place where the plant was grown and harvested, discovering that it was cultivated in the mountains of Tangut province. The value of rhubarb can be seen in Ruy Gonzáles de Clavijo's report of his embassy in 1403–1405 to Timur in
Samarkand fa, سمرقند , native_name_lang = , settlement_type = City , image_skyline = , image_caption = Clockwise from the top:Registan square, Shah-i-Zinda necropolis, Bibi-Khanym Mosque, view inside Shah-i-Zinda, ...
: "The best of all merchandise coming to Samarkand was from China: especially silks, satins, musk, rubies, diamonds, pearls, and rhubarb...." The high price, as well as the increasing demand from apothecaries, stimulated efforts to cultivate the different species of rhubarb on European soil. Certain species came to be grown in England to produce the roots.A Modern Herbal , Rhubarbs
Botanical.com. Retrieved on 17 August 2019.
The local availability of the plants grown for medicinal purposes, together with the increasing abundance and decreasing price of sugar in the 18th century, galvanised its culinary adoption. Grieve claims a date of 1820 in England. Rhubarb was harvested in Scotland from at least 1786, having been introduced to the Botanical Garden in Edinburgh by the traveller
Bruce of Kinnaird James Bruce of Kinnaird (14 December 1730 – 27 April 1794) was a Scottish traveller and travel writer who confirmed the source of the Blue Nile. He spent more than a dozen years in North Africa and Ethiopia and in 1770 became the first Europ ...
in 1774. He brought the seeds from Abyssinia and they produced 3000 plants. Though it is often asserted that rhubarb first came to the United States in the 1820s,
John Bartram John Bartram (March 23, 1699 – September 22, 1777) was an American botanist, horticulturist, and explorer, based in Philadelphia, Pennsylvania, for most of his career. Swedish botanist and taxonomist Carl Linnaeus said he was the "greatest na ...
was growing medicinal and culinary rhubarbs in Philadelphia from the 1730s, planting seeds sent to him by Peter Collinson. From the first, the familiar garden rhubarb was not the only ''Rheum'' in American gardens: Thomas Jefferson planted '' R. undulatum'' at Monticello in 1809 and 1811, observing that it was "Esculent rhubarb, the leaves excellent as Spinach."


Cultivars

The advocate of organic gardening
Lawrence D. Hills Lawrence Donegan Hills (2 July 1911 – 20 September 1990) was a British horticulturalist and writer. In 1954, he founded the Henry Doubleday Research Association (HDRA; now Garden Organic) in Bocking, near Braintree, Essex. By the time he retir ...
listed his favourite rhubarb varieties for flavour as 'Hawke's Champagne', 'Victoria', 'Timperley Early', and 'Early Albert', also recommending 'Gaskin's Perpetual' for having the lowest level of oxalic acid, allowing it to be harvested over a much longer period of the growing season without developing excessive sourness. The Royal Horticultural Society has the UK's national collection of rhubarb that comprises 103 varieties. In 2021–2022 this was moved from southern England to the more northern garden RHS Bridgewater where winter cold and rainfall are better suited for rhubarb. The following cultivars have gained the Royal Horticultural Society’s
Award of Garden Merit The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The Award of Garden Merit ...
: *’Grandad's Favourite’ *’Reed's Early Superb’ *’Stein's Champagne’ *’Timperley Early’


Uses

Rhubarb is grown primarily for its fleshy leafstalks, technically known as petioles. The use of rhubarb stalks as food is a relatively recent innovation. This usage was first recorded in 18th- to 19th-century England after affordable
sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
became more widely available. Commonly, it is stewed with sugar or used in pies and desserts, but it can also be put into savoury dishes or pickled. Rhubarb can be dehydrated and infused with fruit juice. In the United States, it is usually infused with strawberry juice to mimic the popular
strawberry rhubarb pie Rhubarb pie is a pie with a rhubarb filling. It is popular in the UK, where rhubarb has been cultivated since the 1600s, and the leaf stalks eaten since the 1700s. Besides diced rhubarb, it almost always contains a large amount of sugar to ba ...
.


Food

The species '' Rheum ribes'' has been eaten in the
Islamic world The terms Muslim world and Islamic world commonly refer to the Islamic community, which is also known as the Ummah. This consists of all those who adhere to the religious beliefs and laws of Islam or to societies in which Islam is practiced. In ...
since the 10th century. In Northern Europe and North America, the stalks are commonly cut into pieces and stewed with added sugar until soft. The resulting compote, sometimes thickened with corn starch, can then be used in pies, tarts and crumbles. Alternatively, greater quantities of sugar can be added with
pectin Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component of ...
to make
jams Jams or JAMS may refer to: *Plural form of jam, a type of fruit preserve *Jams (clothing line) *JAMS (organization), United States organization that provides alternative dispute resolution services *The JAMs, former name of The KLF, a British band ...
. A paired spice used is
ginger Ginger (''Zingiber officinale'') is a flowering plant whose rhizome, ginger root or ginger, is widely used as a spice A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices ...
, although
cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...
and nutmeg are also common additions. In the United Kingdom, as well as being used in the typical pies, tarts and crumbles, rhubarb compote is also combined with whipped cream or custard to make rhubarb
fool Fool, The Fool, or Fools may refer to: *A jester, also called a ''fool'', a type of historical entertainer known for their witty jokes *An insult referring to someone of low intelligence or easy gullibility Arts, entertainment and media Fictio ...
. In the United States, the common usage of rhubarb in pies has led to it being nicknamed "pie plant", by which it is referred to in 19th-century cookbooks. Rhubarb in the US is also often paired with strawberries to make strawberry-rhubarb pie, though some rhubarb purists jokingly consider this "a rather unhappy marriage". Rhubarb can also be used to make alcoholic drinks, such as
fruit wine Fruit wines are fermented alcoholic beverages made from a variety of base ingredients (other than grapes); they may also have additional flavors taken from fruits, flowers, and herbs. This definition is sometimes broadened to include any alcohol ...
s or Finnish rhubarb sima (mead). It is also used to make Kompot.


Nutrition

Raw rhubarb is 94% water, 5% carbohydrates, 1% protein, and contains negligible fat (table). In a reference amount, raw rhubarb supplies of food energy, and is a rich source of vitamin K (28% of the Daily Value, DV), a moderate source of vitamin C (10% DV), and contains no other
micronutrient Micronutrients are nutrient, essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for exam ...
s in significant amounts (table).


Traditional Chinese medicine

In traditional Chinese medicine, rhubarb roots of several species were used as a laxative for several millennia, although there is no clinical evidence to indicate such use is effective.


Phytochemistry and potential toxicity

The roots and stems contain
anthraquinones ''For the parent molecule 9,10-anthraquinone, see anthraquinone'' Anthraquinones (also known as anthraquinonoids) are a class of naturally occurring phenolic compounds based on the 9,10-anthraquinone skeleton. They are widely used industrially an ...
, such as emodin and
rhein Rhein may refer to: Places * Rhine, a major river in Europe (german: Rhein, link=no) * Rhein, a village in the municipality of Morsbach in North Rhine-Westphalia, Germany * Rhein (Ostpreussen), a former name of the town Ryn in Poland Ships * ...
. The anthraquinones have been separated from powdered rhubarb root for purposes in traditional medicine, although long-term consumption of the plant has been associated with acute kidney failure. The rhizomes contain stilbenoid compounds (including rhaponticin), and the
flavanol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compo ...
glucoside A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes. The name was o ...
s (+)- catechin-5-O-glucoside and (−)- catechin-7-O-glucoside.


Oxalic acid

Rhubarb leaves contain
poison Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
ous substances, including
oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...
, a nephrotoxin. The long term consumption of oxalic acid leads to kidney stone formation in humans. Humans have been poisoned after ingesting the leaves, a particular problem during World War I when the leaves were mistakenly recommended as a food source in Britain. The toxic rhubarb leaves have been used in flavouring extracts, after the oxalic acid is removed by treatment with precipitated chalk (i.e., calcium carbonate). The (median lethal dose) for pure oxalic acid in rats is about 375 mg/kg
body weight Human body weight is a person's mass or weight. Strictly speaking, body weight is the measurement of weight without items located on the person. Practically though, body weight may be measured with clothes on, but without shoes or heavy accessor ...
, or about 25 grams for a human. Other sources give a much higher oral LDLo (lowest published lethal dose) of 600 mg/kg. While the oxalic acid content of rhubarb leaves can vary, a typical value is about 0.5%, meaning a 65 kg adult would need to eat 4 to 8 kg (9 to 18 lbs) to obtain a lethal dose, depending on which lethal dose is assumed. Cooking the leaves with baking soda can make them more poisonous by producing soluble oxalates. The leaves are believed to also contain an additional, unidentified toxin, which might be an anthraquinone glycoside (also known as senna glycosides). In the petioles (leaf stalks), the proportion of oxalic acid is about 10% of the total 2–2.5% acidity, which derives mainly from malic acid. Serious cases of rhubarb poisoning are not well documented. Both fatal and non-fatal cases of rhubarb poisoning may be caused not by oxalates, but rather by toxic anthraquinone glycosides.


Pests

The rhubarb curculio, ''
Lixus concavus ''Lixus concavus'', commonly called the rhubarb curculio, is a species of weevil. Rhubarb (''Rheum'' species) is a host, together with dock, sunflower, and thistle. Characteristics ''L. concavus'' has a distinctive long snout and geniculate a ...
'', is a
weevil Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...
. Rhubarb is a host, damage being visible mainly on the leaves and stalks, with gummosis, and oval or circular feeding and/or egg-laying sites. Hungry wildlife may dig up and eat rhubarb roots in the spring, as stored starches are turned to sugars for new foliage growth.


In Zoroastrian mythology

According to certain Middle Persian Zoroastrian texts dealing with the creation of humankind, Mashya and Mashyana, the first human couple, first manifested on the earth as conjoined homunculi growing attached to a (ghostly) rhubarb plant. When
Gayomart Keyumars or Kiomars ( fa, کیومرث) was the name of the first king (shah) of the Pishdadian dynasty of Iran according to the ''Shahnameh''. The name appears in Avestan in the form of ''𐬔𐬀𐬌𐬌𐬊 𐬨𐬆𐬭𐬆𐬙𐬀𐬥 Gai ...
, the prototype of humanity, finally died as a result of the machinations of Ahriman the principle of evil and Jeh the demonic whore, he fell onto his left side and ejaculated onto the ground. The sun's rays gradually purified his semen, two parts being cared for by the messenger deity Neryosang and one part by Spendarmad,
Amesha Spenta In Zoroastrianism, the Amesha Spenta ( ae, , Aməša Spəṇta—literally "Immortal (which is) holy/bounteous/furthering") are a class of seven divine entities emanating from Ahura Mazda, the highest divinity of the religion. Later Middle Persian ...
of the Earth. After the passage of forty years, Spendarmad's portion gave rise to the rhubarb plant bearing the human couple, who were then animated by the supreme deity Ohrmazd by means of the Farr ('kingly glory').
5. After Gayomard had emitted his seed as he lay dying, they filtered the seed by means of the light of the Sun; Neryosang guarded two parts of it, and Spandarmad accepted one part; and t remained within the earthfor forty years. 6. n the completion of forty years,Mashye and Mashyane grew up from the earth in the astral body of a ''rivas'' (= rhubarb) plant having one stem of fifteen leaves, in such wise that their hands rested behind over their shoulders, and they were joined to each other, of the same height, and of the same product. 7. Betwixt them both light came up; and they were of such uniform height that it asnot evident which was the male and which the female, and ithwhich
f them F, or f, is the sixth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''ef'' (pronounced ), and the plural is ''efs''. Hist ...
was the light
iven by Iven is a municipality in the Vorpommern-Greifswald district, in Mecklenburg-Vorpommern, Germany. Notable residents *Georg Detlev von Flemming Georg Detlev von Flemming (Polish: Jerzy Detloff Fleming) (3 March 1699 – 10 December 1771) was a ...
Ohrmazd,
hat is, the light onto which the seed of the mortal being was affixed. A hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory. Hats which incorporate mecha ...
.. 9. Then both of them changed from the astral body of a plant in to the astral body of a man, and that light, which is the soul, entered spiritually into them, that is, verily, they had grown up in the semblance of a tree, whose fruit was the ten races of mankind.
Iranian or Greater '' Bundahishn'' ( 8th–9th century CE )
selected verses from Chapter 14: 'Concerning Humankind'
( extract from the English translation by Behramgore Tehmuras Anklesaria ).A translation of the Iranian or Greater Bundahišn
by Anklesaria, Behramgore Tehmuras (1956) at Avesta.org


Gallery

File:Rhubarb in market 1.JPG, Rhubarb displayed for sale at a market File:A 19th century apothecary jar for Rhubarb.jpg, A 19th-century apothecary jar for rhubarb File:Strawberry Rhubarb, Dried Fruit.jpg, Dried strawberry-flavoured rhubarb


References


Further reading

*Thompson, Fed S
Rhubarb or Pie Plant Culture
1894. 1894
*Morse, J. E
The New Rhubarb Culture
1901. 1901

1903

1909
*Bland, Reginald
Winter rhubarb, culture and marketing
1915. *


External links

* * {{Authority control Medicinal plants Perennial vegetables Plants described in 1753 Taxa named by Carl Linnaeus Rheum (plant) Stem vegetables Nephrotoxins