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'''''Asparagus officinalis''''' is a flowering plant species in the genus ''[[Asparagus (genus)|Asparagus]]'' from which the [[vegetable]] known as '''asparagus''' is obtained. It is native to most of [[Europe]], northern [[Africa]] and western [[Asia]].<ref name=fe>Flora Europaea: [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Asparagus&SPECIES_XREF=officinalis&TAXON_NAME_XREF=&RANK= ''Asparagus officinalis'']</ref><ref name=empp>Euro+Med Plantbase Project: [http://ww2.bgbm.org/_EuroPlusMed/PTaxonDetail.asp?NameId=38660&PTRefFk=500000 ''Asparagus officinalis'']</ref><ref name=grin>Germplasm Resources Information Network: [http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?300050 ''Asparagus officinalis'']</ref> It is now also widely cultivated as a [[vegetable]] crop.<ref name="prota">Grubben, G.J.H. & Denton, O.A. (2004) Plant Resources of Tropical Africa 2. Vegetables. PROTA Foundation, Wageningen; Backhuys, Leiden; CTA, Wageningen.</ref>

==Commercial production==
[[Image:Asparagus_production_2007.png|thumb|center|600px|Asparagus output in 2007 shown by tonnage.]]
As of 2007, [[Peru]] is the world's leading asparagus exporter, followed by [[China]] and [[Mexico]].<ref>{{cite web | url=http://www.fas.usda.gov/htp/Hort_Circular/2005/08-05/Asparagus%20article.pdf | publisher=World Horticultural Trade & U.S. Export Opportunities | title=World Asparagus Situation & Outlook | author=United States Department of Agriculture | accessdate=2007-02-27|format=PDF}}</ref> The top asparagus importers (2004) were the United States (92,405 tonnes), followed by the [[European Union]] (external trade) (18,565 tonnes), and [[Japan]] (17,148 tonnes).<ref>According to Global Trade Atlas and [[U.S. Census Bureau]] statistics</ref> The United States' production for 2005 was on {{convert|218.5|km2|acre}} and yielded 90,200 tonnes,<ref name=nass>{{cite book | author=USDA | title=Vegetables 2005 Summary | month=January | year=2006 | publisher=National Agricultural Statistics Service}}</ref> making it the world's third largest producer, after China (5,906,000 tonnes) and Peru (206,030 tonnes).<ref>{{cite web | url=http://faostat.fao.org/site/336/DesktopDefault.aspx?PageID=336 | title = Food and Agriculture Organisation Statistics (FAOSTAT) | accessdate=2007-11-11}}</ref> U.S. production was concentrated in [[California]], [[Michigan]], and [[Washington]].<ref name=nass/> The crop is significant enough in California's [[Sacramento-San Joaquin River Delta]] region that the city of [[Stockton, California|Stockton]] holds a festival every year to celebrate it, as does the city of Hart, Michigan, complete with a parade and asparagus queen. The [[Vale of Evesham]] in [[Worcestershire]] is heralded as the largest producer within Northern Europe, celebrating like Stockton, with a week long festival every year involving auctions of the best crop and locals dressing up as spears of asparagus as part of the British Asparagus Festival.<ref>{{cite web | url=http://www.british-asparagus.co.uk/asparagus_festival.php#cotswolds | title=British Aparagus Festival}}</ref>

==Biology==
Asparagus is a [[herbaceous]] [[perennial plant]] growing to {{convert|100|-|150|cm}} tall, with stout larissa stems with much-branched feathery foliage. The "leaves" are in fact needle-like cladodes (modified stems) in the axils of scale leaves; they are {{convert|6|–|32|mm}} long and {{convert|1|mm}} broad, and clustered 4–15 together.Its roots are tuberous .The [[flower]]s are bell-shaped, greenish-white to yellowish, {{convert|4.5|–|6.5|mm}} long, with six [[tepal]]s partially fused together at the base; they are produced singly or in clusters of 2-3 in the junctions of the branchlets. It is usually [[plant sexuality|dioecious]], with male and female flowers on separate plants, but sometimes hermaphrodite flowers are found. The [[fruit]] is a small red berry 6–10&nbsp;mm diameter.

Plants native to the western coasts of Europe (from northern [[Spain]] north to [[Ireland]], [[Great Britain]], and northwest [[Germany]]) are treated as ''Asparagus officinalis'' subsp. ''prostratus'' (Dumort.) Corb., distinguished by its low-growing, often prostrate stems growing to only {{convert|30|–|70|cm}} high, and shorter cladodes {{convert|2|–|18|mm}} long.<ref name=fe/><ref name=blamey/> It is treated as a distinct species ''Asparagus prostratus'' Dumort by some authors.<ref name=fnwe>Flora of NW Europe: [http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=4839 ''Asparagus prostratus'']</ref><ref name=grin1>Germplasm Resources Information Network: [http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?5538 ''Asparagus prostratus'']</ref>

==History==
Asparagus has been used from early times as a vegetable and medicine, owing to its delicate flavour and [[diuretic]] properties. There is a [[recipe]] for cooking asparagus in the oldest surviving book of recipes, [[Apicius]]’s third century AD ''[[De re coquinaria]],'' Book III. It was cultivated by the ancient Egyptians, Greeks and Romans, who ate it fresh when in season and dried the vegetable for use in winter. It lost its popularity in the Middle Ages but returned to favour in the seventeenth century.<ref name="OBFP">{{cite book | last =Vaughan | first =J.G. | authorlink = | coauthors = Geissler, C.A. | title =The New Oxford Book of Food Plants | publisher = Oxford University Press | year=  1997}}</ref>

==Uses==
===Culinary===
[[Image:Asparagus3.JPG|left|thumb|Three types of asparagus on a shop display, with white asparagus at the back and green asparagus in the middle. The plant at the front is ''[[Ornithogalum pyrenaicum]]'', is commonly called wild asparagus, and sometimes "Bath Asparagus".]]
Only the young shoots of asparagus are eaten.

Asparagus is low in calories, contains no cholesterol, and is very low in sodium. It is a good source of [[folic acid]], [[potassium]], [[dietary fiber]], and [[rutin]]. The [[amino acid]] [[asparagine]] gets its name from asparagus, the asparagus plant being rich in this compound.

The shoots are prepared and served in a number of ways around the world. In Asian-style cooking, asparagus is often stir-fried.  [[Guangzhou|Cantonese]] restaurants in the [[United States]] often serve asparagus stir-fried with [[chicken]], [[shrimp]], or [[beef]], also wrapped in [[bacon]]. Asparagus may also be quickly grilled over charcoal or hardwood embers. It is also used as an ingredient in some stews and soups. In the French style, it is often boiled or steamed and served with [[hollandaise]] sauce, melted butter or [[olive oil]], [[Parmesan cheese]] or [[mayonnaise]]. It may even be used in a [[dessert]].<ref>Asparagus Lime Pie [http://homecooking.about.com/od/pierecipes/r/blpie5.htm Recipe]</ref>  The best asparagus tends to be early growth (meaning first of the season) and is often simply steamed and served along with melted butter. Tall, narrow asparagus cooking pots allow the shoots to be steamed gently, their tips staying out of the water. 

Asparagus can also be [[pickled]] and stored for several years. Some brands may label them as "marinated" which means the same thing.

The bottom portion of asparagus often contains sand and dirt and as such thorough cleaning is generally advised in cooking asparagus.

Green asparagus is eaten worldwide, though the availability of imports throughout the year has made it less of a delicacy than it once was.<ref name=blamey>Blamey, M. & Grey-Wilson, C. (1989). ''Flora of Britain and Northern Europe''. ISBN 0-340-40170-2</ref> However, in the UK, due to the short growing season and demand for local produce, asparagus commands a premium and the "asparagus season is a highlight of the [[foodie]] calendar."<ref>[http://www.british-asparagus.co.uk/ British Asparagus]</ref> In continental northern Europe, there is also a strong seasonal following for local white asparagus, nicknamed "white gold".

[[File:Asparagus officinalis dewdrop.JPG|thumb|Asparagus officinalis with dewdrops.]]

===Medicinal===

Second century physician, [[Galen]], described asparagus as "cleansing and healing." 

Nutrition studies have shown that asparagus is a low-[[calorie]] source of [[folate]] and [[potassium]]. Its stalks are high in [[antioxidants]]. 
"Asparagus provides essential nutrients: six spears contain some 135 micrograms (mcg) of folate, almost half the adult RDI (recommended daily intake), 545 mcg of beta carotene, and 20 milligrams of potassium," notes an article which appeared in 'Reader's Digest.' 
Research suggests folate is key in taming homocysteine, a substance implicated in heart disease. 

Folate is also critical for pregnant mothers, since it protects against neural tube defects in babies. 
Several studies indicate that getting plenty of potassium may reduce the loss of calcium from the body. 

Particularly green asparagus is a good source of vitamin C, packing in six times more than those found in citrus fruits.

Vitamin C helps the body produce and maintain collagen. Considered a wonder protein, collagen helps hold together all the cells and tissues of the body. 

"Asparagus has long been recognized for its medicinal properties," wrote D. Onstad, author of 'Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers and Lovers of Natural Foods.' 

"Asparagus contains substances that act as a diuretic, neutralize ammonia that makes us tired, and protect small blood vessels from rupturing. Its fiber content makes it a laxative too."

==Cultivation==
{{See also|List of asparagus diseases}}
Since asparagus often originates in maritime habitats, it thrives in soils that are too saline for normal weeds to grow in. Thus a little salt was traditionally used to suppress weeds in beds intended for asparagus; this has the disadvantage that the soil cannot be used for anything else. Some places are better for growing asparagus than others. The fertility of the soil is a large factor. "Crowns" are planted in winter, and the first shoots appear in spring; the first pickings or "thinnings" are known as sprue asparagus. Sprue have thin stems.<ref>{{cite web |url=http://www.bbc.co.uk/food/glossary/s.shtml?sprue_asparagus |title=BBC -  Food - Glossary - 'S' |accessdate=2007-06-08 |format= |work=BBC Online }}</ref> 

[[Image:Green Asparagus New York 11 May 2006.jpg|thumb|right|Green asparagus for sale in [[New York City]].]]
White asparagus, known as [[spargel]], is cultivated by denying the plants light and increasing the amount of ultraviolet light the plants are exposed to while they are being grown. Less bitter than the green variety, it is very popular in the [[Netherlands]], [[France]], [[Belgium]] and [[Germany]] where 57,000 tonnes (61% of consumer demands) are produced annually.<ref>{{cite web | url=http://www.germanfoods.org/consumer/documents/WhiteAsparagusPressRelease.doc | publisher=German Agricultural Marketing Board | title=Asparagus: The King of Vegetables | author=Molly Spence | accessdate=2007-02-26|format=DOC}}</ref>

Purple asparagus differs from its green and white counterparts, having high sugar and low [[fibre]] levels. Purple asparagus was originally developed in [[Italy]] and commercialised under the variety name ''Violetto d'Albenga''. Since then, breeding work has continued in countries such as the United States and New Zealand.

In northwestern Europe, the season for asparagus production is short, traditionally beginning on April 23 and ending on [[Midsummer|Midsummer Day]].<ref>[http://www.oxfordtimes.co.uk/leisure/4329516.Time_to_glory_in_asparagus_again/ ''Oxford Times'': "Time to glory in asparagus again".]</ref>

===Companion planting===
Asparagus is a useful [[companion plant]] for tomatoes. The tomato plant repels the asparagus beetle, as do several other common companion plants of tomatoes, meanwhile asparagus may repel some harmful root nematodes that affect tomato plants.<ref>http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Asparagus+officinalis</ref>

==Vernacular names and etymology==
[[Image:AsparagusFernMilduraVictoriaAustralia.jpg|right|thumb|Asparagus in [[Mildura, Victoria|Mildura]], [[Victoria (Australia)|Victoria]], Australia]]
''Asparagus officinalis'' is widely known simply as "asparagus", and may be confused with unrelated plant species also known as "asparagus", such as ''[[Ornithogalum pyrenaicum]]'' known as "Prussian asparagus" for its edible shoots.

The English word "asparagus" derives from classical [[Latin language|Latin]], but the plant was once known in English as ''sperage'', from the [[Medieval Latin]] ''sparagus''. This term itself derives from the [[Greek language|Greek]] ''aspharagos'' or ''asparagos'', and the Greek term originates from the [[Persian language|Persian]] ''asparag'', meaning "sprout" or "shoot". 
[[Image:SkFernlikePlant.jpg|thumb|left|Mature native Asparagus with seed pods in [[Saskatchewan]], [[Canada]] ]]
Asparagus was also corrupted in some places to "sparrow grass"; indeed, the [[Oxford English Dictionary]] quotes [[John Walker (naturalist)|John Walker]] as having written in 1791 that "''Sparrow-grass'' is so general that ''asparagus'' has an air of stiffness and pedantry". In [[Gloucestershire]] and [[Worcestershire]] it is also known simply as "grass". Another known [[Colloquialism|colloquial]] variation of the term, most common in parts of Texas, is "aspar grass" or "asper grass". In the Midwest United States and [[Appalachia]], "spar grass" is a common [[colloquialism]]. Asparagus is commonly known in fruit retail circles as "Sparrows Guts", etymologically distinct from the old term "sparrow grass", thus showing convergent language evolution.

It is known in [[French language|French]] and [[Dutch language|Dutch]] as ''asperge'', in [[Italian language|Italian]] as ''asparago'' (old Italian ''asparagio''), in [[Portuguese language|Portuguese]] as ''espargo hortense'', in [[Spanish language|Spanish]] as ''espárrago'', in [[German language|German]] as ''[[Spargel]]'', in [[Hungarian language|Hungarian]] as ''spárga''.

The Sanskrit name of Asparagus is Shatavari and it has been historically used in India as a part of Ayurvedic medicines.In [[Kannada language|Kannada]], it is known as Ashadhi, Majjigegadde or Sipariberuballi.

==Urine==
The effect of eating asparagus on the eater's urine has long been observed:
:"asparagus... affects the urine with a foetid smell (especially if cut when they are white) and therefore have been suspected by some physicians as not friendly to the kidneys; when they are older, and begin to ramify, they lose this quality; but then they are not so agreeable"<ref>{{citation
|author=Arbuthnot J
|year=1735
|author-link=John Arbuthnot
|title=An Essay Concerning the Nature of Aliments 3rd ed.
|pages=64261–262
|publisher=J. Tonson
|city=London}}</ref>

[[Marcel Proust]] claimed that asparagus "...transforms my chamber-pot into a flask of perfume."<ref>From the French "[...] changer mon pot de chambre en un vase de parfum," ''Du côté de chez Swann,'' Gallimard, 1988.</ref>

=== Chemistry ===
Certain compounds in asparagus are [[metabolism|metabolized]] giving urine a distinctive smell due to various [[sulfur]]-containing degradation products, including various [[thiol]]s, [[thioester]]s, and ammonia.<ref>{{cite journal | journal=Science | volume=189 | pages=810–11 | year=1975  | author=White RH. | title=Occurrence of S-methyl thioesters in urines of humans after they have eaten asparagus | url=http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=1162354 | pmid=1162354 | doi = 10.1126/science.1162354 }}</ref>

The [[volatile organic compound]]s responsible for the smell are identified as:<ref>{{cite journal
|year=1987
|title=The chemical nature of the urinary odour produced by man after asparagus ingestion
|journal=Xenobiotica
|volume=17
|pages=1363–1371
|pmid=3433805
|author=Waring RH, Mitchell SC and Fenwick GR
}}</ref><ref>[http://dmd.aspetjournals.org/cgi/content/full/29/4/539#SEC2 Food Idiosyncrasies: Beetroot and Asparagus]</ref>
* [[methanethiol]],
* [[dimethyl sulfide]],
* [[dimethyl disulfide]],
* bis(methylthio)methane,
* [[dimethyl sulfoxide]], and
* [[dimethyl sulfone]].
Subjectively, the first two are the most pungent, while the last two (sulfur-oxidized) give a sweet aroma. A mixture of these compounds form a "reconstituted asparagus urine" odor.

This was first investigated in [[1891]] by [[Marceli Nencki]], who attributed the smell to [[methanethiol]].<ref>{{cite journal
|last=Nencki
|first=Marceli
|author-link=Marceli Nencki
|year=1891
|title=Ueber das vorkommen von methylmercaptan im menschlichen harn nach spargelgenuss
|journal=Arch Exp Path Pharmak
|volume=28
|pages=206–209
|doi=10.1007/BF01824333
}}</ref>

These compounds originate in the asparagus as [[asparagusic acid]] and its derivatives, as these are the only sulfur-containing compounds unique to asparagus. As these are more present in young asparagus, this accords with the observation that the smell is more pronounced after eating young asparagus.

=== Metabolism ===
The biological mechanism for the production of these compounds is less clear.

The speed of onset of urine smell has been estimated to occur within 15–30 minutes of ingestion.<ref>{{cite web | url=http://www.webmd.com/content/article/43/1671_51089 | publisher=WebMD | title=Eau D'Asparagus | author=Somer, E. | date=[[August 14]] [[2000]] | accessdate=2006-08-31}}</ref>
Research completed and verified by Dr. R. McLellan from the University of Waterloo.

=== Prevalence of production and identification ===
Observational evidence from the 1950s showed that many people did not know about the phenomenon of asparagus urine. There is debate about whether all (or only some) people produce the smell, and whether all (or only some) people identify the smell.

It was originally thought this was because some of the population digested asparagus differently than others, so that some people excreted odorous urine after eating asparagus, and others did not. However, in the 1980s three studies from France,<ref> {{cite web | url=http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1379934&blobtype=pdf | journal=Br J. Clin. Pharmac | title=Odorous urine in man after asparagus | author=C. RICHER1, N. DECKER2, J. BELIN3, J. L. IMBS2, J. L. MONTASTRUC3 &  J. F. GIUDICELLI |date=May 1989}}</ref> China and Israel published results showing that producing odorous urine from asparagus was a universal human characteristic. The Israeli study found that from their 307 subjects all of those who could smell 'asparagus urine' could detect it in the urine of anyone who had eaten asparagus, even if the person who produced it could not detect it himself.<ref>{{cite journal | url=http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1379935&blobtype=pdf | journal=Br J. Clin. Pharmac | title=Asparagus and malodorous urine | author=S. C. MITCHELL |date=May 1989}}</ref> Thus, it is now believed that most people produce the odorous compounds after eating asparagus, but only about 22% of the population have the [[autosomal]] genes required to smell them.<ref>{{cite web | url=http://www.guardian.co.uk/food/story/0,,1576765,00.html | publisher=The Guardian | title=The scientific chef: asparagus pee| date=[[September 23]] [[2005]] | accessdate=2007-04-21}}</ref><ref>{{cite web | url=http://www.discovery.com/area/skinnyon/skinnyon970115/skinny1.html | title=Why Asparagus Makes Your Pee Stink | author=Hannah Holmes | publisher=Discover.com }}</ref><ref>{{cite journal | journal=Br Med J | volume=281 | pages=1676 | year= 1980 | author=Lison M, Blondheim SH, Melmed RN. | title=A polymorphism of the ability to smell urinary metabolites of asparagus | url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=7448566 | pmid=7448566 | doi =10.1136/bmj.281.6256.1676  }}</ref>

==References==
[[Image:AsparagusinAutumn3.JPG|thumb|250px|right|Asparagus foliage shines bright yellow in autumn]]
{{reflist}}

==External links==
{{commonscat|Asparagus officinalis}}
{{Cookbook|Asparagus}}
* [http://database.prota.org/dbtw-wpd/exec/dbtwpub.dll?AC=QBE_QUERY&BU=http%3A%2F%2Fdatabase.prota.org%2Fsearch.htm&TN=PROTAB~1&QB0=AND&QF0=Species+Code&QI0=Asparagus+officinalis&RF=Webdisplay PROTAbase on ''Asparagus officinalis'']
* [http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Asparagus+officinalis ''Asparagus officinalis''] - Plants for a Future database entry
* {{PDFlink|[http://www.fas.usda.gov/htp/Hort_Circular/2005/08-05/Asparagus%20article.pdf World Asparagus Situation and Outlook]|55.0&nbsp;[[Kibibyte|KiB]]<!-- application/pdf, 56385 bytes -->}} - 2005 USDA report
* [http://ohioline.osu.edu/b826/index.html Asparagus Production Management and Marketing] - commercial growing (OSU bulletin)
* [http://www.asparagusfest.com The Stockton Asparagus Festival] - held annually every April in [[Stockton, California|Stockton]], [[California]]
*[http://www.plants.am/wiki/Asparagus''Growing Asparagus''] Guide to growing Asparagus
*[http://aesop.rutgers.edu/~asparagus/research/asparagus.html Asparagus Breeding Program at Rutgers, the State University of New Jersey]

[[Category:Asparagus]]
[[Category:Medicinal plants]]
[[Category:Stem vegetables]]
[[Category:Asparagales genera]]