rhubarb
{{Short description|Species of herbaceous perennial plant with fleshy, sour edible stalks }}
{{About||other uses|Rhubarb (disambiguation)|the cartoon|Roobarb}}
{{Use dmy dates|date=June 2021}}
{{Use British English|date=April 2018}}
{{Speciesbox
| name = Rhubarb (culinary hybrid)
| image = Rheum rhabarbarum.2006-04-27.uellue.jpg
| genus = Rheum
| species = × hybridum
| authority = Murray{{cite web |title=Rheum × hybridum Murray |work=Plants of the World Online |publisher=Royal Botanic Gardens, Kew|url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:696744-1 |access-date=10 March 2019 }}
}}
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.{{Cite journal|last1=Foust|first1=Clifford M.|last2=Marshall|first2=Dale E.|date=1 November 1991|title=Culinary Rhubarb Production in North America: History and Recent Statistics|url=https://journals.ashs.org/hortsci/view/journals/hortsci/26/11/article-p1360.xml|journal=HortScience|volume=26|issue=11|pages=1360–1363|doi=10.21273/hortsci.26.11.1360|issn=0018-5345|doi-access=free}} The plant is a herbaceous perennial that grows from short, thick rhizomes. Historically, different plants have been called "rhubarb" in English. The large, triangular leaves contain high levels of oxalic acid and anthrone 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 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.{{Cite journal |last1=Tanhuanpää |first1=Pirjo |last2=Suojala-Ahlfors |first2=Terhi |last3=Hartikainen |first3=Merja |date=2019 |title=Genetic diversity of Finnish home garden rhubarbs (Rheum spp.) assessed by simple sequence repeat markers |journal=Genetic Resources and Crop Evolution |volume=66 |issue=1 |pages=17–25 |doi=10.1007/s10722-018-0692-8 |s2cid=52821042 |name-list-style=amp }} In appearance, samples of culinary rhubarb vary on a continuum between R. rhaponticum and R. rhabarbarum. However, modern rhubarb cultivars are tetraploids with 2n = 44, in contrast to 2n = 22 for the wild species.{{Cite journal |last1=Libert |first1=Bo |last2=Englund |first2=Roger |date=1989 |title=Present Distribution and Ecology of Rheum rhaponticum (Polygonaceae) |journal=Willdenowia |volume=19 |issue=1 |pages=91–98 |jstor=3996925 |name-list-style=amp }}
Rhubarb is a vegetable and is often put to the same culinary uses as fruits.{{Cite book|last=Hood|first=Karen Jean Matsko|url=https://books.google.com/books?id=ftMSBQAAQBAJ&pg=PA20|title=Rhubarb Delights Cookbook: A Collection of Rhubarb Recipes|date=2014-01-01|publisher=Whispering Pine Press International
|place= Spokane Valley
| pages= 20, 22
|isbn=978-1-930948-00-6|language=en}} The leaf stalks can be used raw while they have a crisp texture, 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.{{cite web
| url = https://www.rhs.org.uk/Plants/Search-Results?form-mode=true&context=b%3D10%26hf%3D10%26l%3Den%26q%3Drheum%26s%3Ddesc%2528plant_merged%2529%26sl%3DplantForm&query=rhubarb
| title = RHS Plantfinder – Rhubarb | access-date = 23 September 2018}}
Etymology
The word rhubarb is likely to have derived in the 14th century from the Old French {{lang|fr|rubarbe}}, which came from the Latin {{lang|la|rheubarbarum}} and Greek {{transliteration|grc|rha barbaron}}, meaning 'foreign rhubarb'.{{Cite web|title=Rhubarb|publisher= Online Etymology Dictionary, Douglas Harper Inc.|url=https://www.etymonline.com/word/rhubarb|date=2020|access-date=3 June 2020}} The Greek physician Dioscorides used the Greek word {{lang|grc|ῥᾶ}} ({{transliteration|grc|rha}}), whereas Galen later used {{lang|grc|ῥῆον}} ({{transliteration|grc|rhēon}}), Latin {{lang|la|rheum}}. These in turn derive from a Persian name for species of Rheum.{{Citation |mode=cs1 |last1=Gilbert-Carter |first1=H. |date=1955 |title=Glossary of the British Flora |edition=2nd |publisher=Cambridge University Press |page=69}} 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.{{cite book |last=Theroux |first=Alexander |date=2017 |title=Einstein's Beets |url= |location= |publisher=Fantagraphics Books, Seattle Washington |page= 47|isbn=978-1-60699-976-9}}
Cultivation
File:Rheum rhabarbarum (Rabarber) Frambozenrood bloeiwijze.jpg
Rhubarb is grown widely, and with greenhouse 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.{{cite web |title=Rhubarb |url=https://www.rhs.org.uk/vegetables/rhubarb/grow-your-own |website=Royal Horticultural Society |access-date=23 January 2022}} 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. {{ISBN|978-0-672-51831-7}} After forcing for commercial production, the crowns are usually discarded. In temperate climates, rhubarb is one of the first food plants harvested, usually in mid- to late spring (April or May in the Northern Hemisphere, 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. {{ISBN|978-0-684-80001-1}} These sheds are dotted around the "Rhubarb Triangle" in Yorkshire between Wakefield, Leeds, and Morley.{{cite web|author=Wakefield Metropolitan District Council|url=http://www.wakefield.gov.uk/CultureAndLeisure/HistoricWakefield/Rhubarb/default.htm|title=Rhubarb|access-date=12 March 2006|archive-url=https://web.archive.org/web/20080930091049/http://www.wakefield.gov.uk/CultureAndLeisure/HistoricWakefield/Rhubarb/default.htm|archive-date=30 September 2008}}
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.{{cite journal |title=Rhubarb |url=https://extension.oregonstate.edu/crop-production/vegetables/rhubarb |journal=Ag - Processed Vegetables |date=19 June 2018 |publisher=Oregon State University |access-date=18 November 2022|last1=Support |first1=Extension Web }} 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;{{Citation|author=Learn To Grow|title=How To Harvest Rhubarb|date=31 July 2015|url=https://www.youtube.com/watch?v=xU392gqTHLU| archive-url=https://ghostarchive.org/varchive/youtube/20211107/xU392gqTHLU| archive-date=2021-11-07 | url-status=live|access-date=17 May 2017}}{{cbignore}} half of all US commercial production is in Pierce County, Washington.{{cite web|url=http://www.co.pierce.wa.us/pc/abtus/profile/agriculture.htm|archive-url=https://web.archive.org/web/20090731000751/http://www.co.pierce.wa.us/pc/abtus/profile/agriculture.htm|archive-date=31 July 2009|title=Pierce County Agriculture|date=31 July 2009|access-date=30 July 2018}} 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, which migrates from the leaves and can cause illness.
{{cite web|title=Growing Rhubarb in the Home Garden|publisher=Ohio State University Extension Fact Sheet|url=http://ohioline.osu.edu/hyg-fact/1000/1631.html|access-date=4 June 2013|archive-url=https://web.archive.org/web/20130605223334/http://ohioline.osu.edu/hyg-fact/1000/1631.html|archive-date=5 June 2013}}
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 anthocyanins, and varies according to both rhubarb variety and production technique. The colour is not related to its suitability for cooking.{{cite web|url=http://www.rhubarbinfo.com/rhubarb-varieties.html |title=Rhubarb Varieties |publisher=Rhubarbinfo.com |date=1 September 2004 |access-date=5 March 2010}}
=Historical cultivation=
The Chinese call rhubarb "the great yellow" ({{transliteration|zh|dà huáng}} {{lang|zh|大黃}}), and have used rhubarb root for medicinal purposes.{{cite web|url=http://pharmaxchange.info/press/2012/12/pharmacognosy-of-rhubarb/|title=Pharmacognosy of Rhubarb|author=Mehta, Sweety |date=27 December 2012|work=PharmaXChange.info}} It appears in The Divine Farmer's Herb-Root Classic, which is thought to have been compiled about 1,800 years ago.{{Cite book|url=https://books.google.com/books?id=apAPal8iAxgC&pg=PA270|title=Origin and History of All the Pharmacopeial Vegetable Drugs, Chemicals and Origin and History of All the Pharmacopeial Vegetable Drugs, Chemicals and Preparations with Bibliography|volume=1|author=John Uri Lloyd|year=1921|publisher=Read Books |isbn=978-1-4086-8990-5}} Though Dioscurides' description of {{lang|grc|ρηον}} or {{lang|grc|ρά}} indicates that a medicinal root brought to Greece from beyond the Bosphorus 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, reaching Europe in the 14th century through the ports of Aleppo and Smyrna, where it became known as "Turkish rhubarb".{{cite book|last=Warmington|first=E. H.|title=The Commerce Between the Roman Empire and India|url=https://books.google.com/books?id=u9w8AAAAIAAJ&pg=PA207|year=1928|publisher=Cambridge University Press|location=Cambridge|isbn=978-1-00-136124-6|page=207ff}} Later,{{when|date=May 2024}} it began to arrive via new maritime routes and overland through Russia. The "Russian rhubarb" was the most valued, probably because of the rhubarb-specific quality control system maintained by the Russian Empire.{{Cite book| last = Monahan| first = Erika| chapter = Locating rhubarb |chapter-url=https://www.academia.edu/24221351 | title = Early modern things: objects and their histories, 1500–1800| editor-last = Findlen| editor-first = Paula| publisher = Routledge| isbn = 978-0-415-52051-5| pages = 227–251| location = Abingdon| date = 2013}} The 2020 edition of Pharmacopoeia of the People's Republic of China lists the following species as medicinally acceptable: Rheum officinale, Rheum palmatum, and Rheum tanguticum.{{cite book |title=中国药典第一部 |page=24 |edition=2020 |url=https://db.ouryao.com/yd2020/view.php?id=f82dba38c5}} Grieve describes "Turkish rhubarb" as a mixture of R. palmatum and R. rhaponticum.
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, opium, and saffron. The merchant explorer Marco Polo 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: "The best of all merchandise coming to Samarkand was from China: especially silks, satins, musk, rubies, diamonds, pearls, and rhubarb...."Quoted in {{cite book|author=Wood, Frances |title=The Silk Road: Two Thousand Years in the Heart of Asia|url=https://archive.org/details/silkroadtwothous0000wood|url-access=registration |year=2002|publisher=University of California Press|isbn=978-0-520-24340-8|page=[https://archive.org/details/silkroadtwothous0000wood/page/13 13]}}
The high price, as well as the increasing demand from apothecaries, stimulated efforts to cultivate the different species of rhubarb on European soil. R. rhaponticum × R. officinale came to be grown in England to produce the roots. R. alpinus was also allowed to grow wild.{{Cite web|series=A Modern Herbal
| last= Grieve| first= M. | year= 1900
| title=Rhubarbs|url=https://botanical.com/botanical/mgmh/r/rhubar14.html|access-date=2023-02-23|website=botanical.com}} 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 in 1774. He brought the seeds from Abyssinia and they produced 3,000 plants.Grants Old and New Edinburgh
Though it is often asserted that rhubarb first came to the United States in the 1820s,Waters, Alice (2002) Chez Panisse Fruit. New York: Harper Collins. p. 278. {{ISBN|978-0-06-019957-9}} John Bartram was growing medicinal and culinary rhubarbs in Philadelphia from the 1730s, planting seeds sent to him by Peter Collinson.{{Cite web|editor=David H
| last= Fry | first= Joel
|date=2012-07-20|title=Did John Bartram introduce rhubarb to North America?|url=https://growinghistory.wordpress.com/2012/07/20/did-john-bartram-introduce-rhubarb-to-north-america/|access-date=2023-02-23|website=Growing History|language=en}} 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."{{Cite web|date=2011-06-12|title=Rhubarb « Thomas Jefferson's Monticello|url=https://www.monticello.org/site/house-and-gardens/rhubarb|access-date=2023-02-23|archive-url=https://web.archive.org/web/20110612082720/https://www.monticello.org/site/house-and-gardens/rhubarb |archive-date=12 June 2011 }}
Cultivars
The advocate of organic gardening Lawrence D. Hills 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.Lawrence D Hills. Organic Gardening. Penguin 1997. page 145
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.{{cite web |title=RHS Bridgwater |url=https://www.instagram.com/p/CY4AQIOqXCK/ |website=RHS Garden Bridgewater Instagram |access-date=23 January 2022}} The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:{{cite web
| url= https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants – Ornamental | date = July 2017
| page = 84 | publisher = Royal Horticultural Society | access-date = 27 September 2018}}
- 'Grandad's Favourite'{{cite web | url = https://www.rhs.org.uk/Plants/102783/i-Rheum-i-×-i-hybridum-i-Grandad-s-Favorite/Details
| title = RHS Plantfinder – Rheum × hybridum 'Grandad's Favourite' | access-date = 23 September 2018}}
- 'Reed's Early Superb'{{cite web
| url = https://www.rhs.org.uk/Plants/56251/i-Rheum-i-×-i-hybridum-i-Reed-s-Early-Superb/Details
| title = RHS Plantfinder – Rheum × hybridum 'Reed's Early Superb'
| access-date = 23 September 2018}}
- 'Stein's Champagne'{{cite web | url = https://www.rhs.org.uk/Plants/49497/i-Rheum-i-×-i-hybridum-i-Stein-s-Champagne/Details
| title = RHS Plantfinder – Rheum × hybridum 'Stein's Champagne' | access-date = 23 September 2018}}
- 'Timperley Early'{{cite web | url = https://www.rhs.org.uk/Plants/61820/i-Rheum-i-×-i-hybridum-i-Timperley-Early/Details
| title = RHS Plantfinder – Rheum × hybridum 'Timperley Early' | access-date = 23 September 2018}}
Uses
{{nutritional value
| name = Rhubarb, raw
| kJ = 88
| water = 94 g
| protein = 0.8 g
| fat = 0.3 g
| carbs = 4.54 g
| fiber = 1.8 g
| sugars = 1.1 g
| calcium_mg = 86
| iron_mg = 0.22
| magnesium_mg = 12
| phosphorus_mg = 14
| potassium_mg = 288
| sodium_mg = 4
| zinc_mg = 0.1
| manganese_mg = 0.196
| vitC_mg = 8
| thiamin_mg = 0.02
| riboflavin_mg = 0.03
| niacin_mg = 0.3
| pantothenic_mg = 0.085
| vitB6_mg = 0.024
| folate_ug = 7
| choline_mg = 6.1
| vitE_mg = 0.27
| vitK_ug = 29.3
| source_usda = 1
| note = [https://fdc.nal.usda.gov/fdc-app.html#/food-details/167758/nutrients Link to USDA Database entry]
| copper_mg = 0.021
| selenium_ug = 1.1
}}
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 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.
=Food=
The species Rheum ribes has been eaten in the Islamic world since the 10th century.{{Cite web|title=Andalusian Cookbook: Table of Contents|url=http://www.daviddfriedman.com/Medieval/Cookbooks/Andalusian/andalusian_contents.htm|access-date=2023-02-23|website=www.daviddfriedman.com}}
In Northern Europe and North America, the stalks are commonly cut into pieces and stewed with added sugar until soft.{{Cite book|last=Lyle|first=Katie Letcher|title=The Complete Guide to Edible Wild Plants, Mushrooms, Fruits, and Nuts: How to Find, Identify, and Cook Them|publisher=FalconGuides|year=2010|isbn=978-1-59921-887-8|edition=2nd|location=Guilford, CN|page=111|oclc=560560606|orig-date=2004}} 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 to make jams. A paired spice used is ginger, although cinnamon 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. 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.{{cite book|author=Neal, Bill |title=Biscuits, Spoonbread and Sweet Potato Pie|page= 308 |publisher=Chapel Hill, NC: University of North Carolina Press|year= 2003|orig-date= 1990|isbn=978-0-8078-5474-7}} 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 wines or Finnish rhubarb sima (mead). It is also used to make Kompot.{{Cite web|title=Rhubarb Compote|url=https://www.bonappetit.com/recipe/rhubarb-compote|access-date=2023-02-23|website=Epicurious|date=7 April 2008 |language=en-US}}
=Nutrition=
Raw rhubarb is 94% water, 5% carbohydrates, 1% protein, and contains negligible fat (table). In a {{convert|100|g|oz|frac=2|abbr=off|adj=on}} reference amount, raw rhubarb supplies {{convert|88|kJ|kcal|abbr=off}} 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 micronutrients in significant amounts (table).
=Traditional Chinese medicine=
In traditional Chinese medicine, rhubarb roots of several species were used as a laxative for several millennia,{{cite book|last=Barceloux|first=Donald G|title=Medical Toxicology of Natural Substances: Foods, Fungi, Medicinal Herbs, Plants, and Venomous Animals|url=https://books.google.com/books?id=aTTBPedwFfAC&pg=PT235|date=2012|publisher=John Wiley & Sons|isbn=978-1-118-38276-9|page=235}} although there is no clinical evidence to indicate such use is effective.
Phytochemistry and potential toxicity
The roots and stems contain anthraquinones, such as emodin and rhein. Emodin "represents a genotoxic risk for humans" while rhein is "a compound devoid of genotoxic capabilities".{{Cite journal |last1=EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) |last2=Younes |first2=Maged |last3=Aggett |first3=Peter |last4=Aguilar |first4=Fernando |last5=Crebelli |first5=Riccardo |last6=Filipič |first6=Metka |last7=Frutos |first7=Maria Jose |last8=Galtier |first8=Pierre |last9=Gott |first9=David |last10=Gundert-Remy |first10=Ursula |last11=Kuhnle |first11=Gunter Georg |last12=Lambré |first12=Claude |last13=Leblanc |first13=Jean-Charles |last14=Lillegaard |first14=Inger Therese |last15=Moldeus |first15=Peter |date=January 2018 |title=Safety of hydroxyanthracene derivatives for use in food |journal=EFSA Journal |volume=16 |issue=1 |pages=e05090 |doi=10.2903/j.efsa.2018.5090 |pmc=7009633 |pmid=32625659}} The anthraquinones have been separated from powdered rhubarb root for purposes in traditional medicine, although long-term consumption of anthraquinones has been associated with acute kidney failure.{{cite web |title=Rhubarb |url=https://www.drugs.com/npp/rhubarb.html |publisher=Drugs.com |access-date=26 January 2020 |date=13 May 2019}}
The rhizomes contain stilbenoid compounds (including rhaponticin), and the flavanol glucosides (+)-catechin-5-O-glucoside and (−)-catechin-7-O-glucoside.{{cite journal|title=Flavanol glucosides from rhubarb and Rhaphiolepis umbellata|journal=Phytochemistry|volume=22|issue=7|pages=1659–1661|doi=10.1016/0031-9422(83)80105-8|year=1983|last1=Nonaka|first1=Gen-Ichiro|last2=Ezaki|first2=Emiko|last3=Hayashi|first3=Katsuya|last4=Nishioka|first4=Itsuo|bibcode=1983PChem..22.1659N }}
=Oxalic acid=
Rhubarb leaves contain poisonous substances, including oxalic acid, 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.{{cite journal | last1 = Robb | first1 = H. F. | year = 1919 | title = Death from rhubarb leaves due to oxalic acid poisoning | journal = J. Am. Med. Assoc. | volume = 73 | issue = 8| pages = 627–628 | doi=10.1001/jama.1919.02610340059028}}Cooper, M. R., Johnson, A. W. (1984). Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. {{ISBN|978-0-11-242529-8}}{{Cite web|title=Rheum x hybridum: The Poison Garden website |url=http://www.thepoisongarden.co.uk/atoz/rheum_x_hybridum.htm|access-date=2023-02-23|archive-url=https://web.archive.org/web/20200223042439/http://www.thepoisongarden.co.uk/atoz/rheum_x_hybridum.htm |archive-date=23 February 2020 }} 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 {{LD50}} (median lethal dose) for pure oxalic acid in rats is about 375 mg/kg body weight,{{cite web|title=Rhubarb poisoning on rhubarbinfo.com|url=http://www.rhubarbinfo.com/rhubarb-poison.html}} or about 25 grams for a {{convert|65|kg|lb|adj=on}} human. Other sources give a much higher oral LDLo (lowest published lethal dose) of 600 mg/kg.{{cite web | author = Safety Officer in Physical Chemistry | title = Safety (MSDS) data for oxalic acid dihydrate | publisher = Oxford University | date = 13 August 2005 | url = http://msds.chem.ox.ac.uk/OX/oxalic_acid_dihydrate.html | access-date = 30 December 2009}} While the oxalic acid content of rhubarb leaves can vary, a typical value is about 0.5%,{{cite journal|vauthors=Pucher GW, Wakeman AJ, Vickery HB |title=The Organic Acids of Rhubarb (Rheum Hybridum) |url=http://www.jbc.org/cgi/content/citation/126/1/43 |journal=Journal of Biological Chemistry|volume=126 |issue=1 |pages=43–54 |year= 1938|doi=10.1016/S0021-9258(18)73892-1 |doi-access=free }} 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.Everist, Selwyn L. (1974), Poisonous Plants of Australia. Angus and Robertson, Melbourne. p. 583. {{ISBN|978-0-207-12773-1}} The leaves are believed to also contain an additional, unidentified toxin,{{cite encyclopedia|url=https://www.nlm.nih.gov/medlineplus/ency/article/002876.htm|title=Rhubarb leaves poisoning|encyclopedia=Medline Plus Medical Encyclopedia}} which might be an anthraquinone glycoside (also known as senna glycosides).{{cite web|url=http://www.cbif.gc.ca/pls/pp/ppack.info?p_psn=171&p_type=all&p_sci=sci|title=Canadian Poisonous Plants Information System|publisher=Cbif.gc.ca|date=1 September 2009|access-date=5 March 2010|archive-url=https://web.archive.org/web/20090122112906/http://www.cbif.gc.ca/pls/pp/ppack.info?p_psn=171&p_type=all&p_sci=sci|archive-date=22 January 2009}}
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.{{cite journal |last1=Barceloux |first1=DG |title=Rhubarb and oxalosis (Rheum species). |journal=Disease-a-Month |date=June 2009 |volume=55 |issue=6 |pages=403–11 |doi=10.1016/j.disamonth.2009.03.011 |pmid=19446684|url=https://kundoc.com/pdf-rhubarb-and-oxalosis-rheum-species-.html}} Both fatal and non-fatal cases of rhubarb poisoning may be caused not by oxalates, but rather by toxic anthraquinone glycosides.{{cite journal |last1=Noonan |first1=SC |last2=Savage |first2=GP |title=Oxalate content of foods and its effect on humans. |journal=Asia Pacific Journal of Clinical Nutrition |date=March 1999 |volume=8 |issue=1 |pages=64–74 |pmid=24393738 |url=http://apjcn.nhri.org.tw/server/APJCN/8/1/64.pdf|doi=10.1046/j.1440-6047.1999.00038.x }}
Pests
Rhubarb is a host to the rhubarb curculio, Lixus concavus, which is a weevil. Damage is mainly visible on leaves and stalks, with gummosis and oval or circular feeding and egg-laying sites.{{cite web|url=http://www.entomology.cornell.edu/cals/entomology/extension/idl/upload/Rhubarb-Curculio.pdf|title=Extension & Public Outreach|work=cornell.edu}}
Hungry wildlife may dig up and eat rhubarb roots in the spring, as stored starches are turned to sugars for new foliage growth.
Cookbook
{{portal|Food}}
{{cookbook}}
- {{Cookbook-inline|Rhubarb Cake}}
- {{Cookbook-inline|Rhubarb Crumble}}
- {{Cookbook-inline|Rhubarb Fool}}
- {{Cookbook-inline|Rhubarb Juice}}
- {{Cookbook-inline|Rhubarb Marmalade}}
- {{Cookbook-inline|Rhubarb Pie}}
- {{Cookbook-inline|Rhubarb Pudding}}
- {{Cookbook-inline|Strawberry Rhubarb Pie}}
Gallery
File:Rhubarb at a market in Genoa.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
File:Phillips(1804) p649 - Russell Square - Rhubarb!.jpg|1804 illustration of a rhubarb seller in London
References
{{Reflist}}
Further reading
- Thompson, Fed S. [https://archive.org/stream/rhubarborpieplan00thom#page/n5/mode/2up Rhubarb or Pie Plant Culture], 1894. ([https://archive.org/details/rhubarborpieplan00thom/page/n6 1894])
- Morse, J. E. [https://archive.org/stream/newrhubarbcultur01mors#page/n3/mode/2up The New Rhubarb Culture], 1901. ([https://books.google.com/books?id=L2BEAAAAYAAJ&pg=PR1 1901]) ([https://archive.org/stream/newrhubarbcultur00mors#page/n3/mode/2up 1903]) ([https://archive.org/stream/newrhubarbcultur00morsuoft#page/n5/mode/2up 1909])
- Bland, Reginald. [https://archive.org/stream/winterrhubarbcul00blan#page/n3/mode/2up Winter rhubarb, culture and marketing], 1915.
- {{cite book|last=Foust| first = Clifford M.| title = Rhubarb: the wondrous drug|year = 1992| publisher = Princeton University Press| isbn = 978-0-691-08747-4}}
External links
{{Commons category|Rhubarb}}
{{Cookbook}}
- {{cite EB1911|wstitle=Rhubarb}}
- [https://web.archive.org/web/20150717121244/http://www.rhubarbinfo.com/ Rhubarb Info] from the [https://www.rhubarbinfo.com/ Rhubarb Compendium]
{{Herbs used as laxatives}}
{{Taxonbar|from=Q7535}}
{{Authority control}}
Category:Plants described in 1753