Sunflower 57622 226138051 2008-07-17T00:04:55Z Smarkflea 6012493 /* Description */ head disamb. {{otheruses}} {{Taxobox | name = Sunflower | image = W&Asunflower.jpg | image_width = 260px | image_caption = | regnum = [[Plantae]] | phylum = [[Flowering plant|Magnoliophyta]] | classis = [[Magnoliopsida]] | ordo = [[Asterales]] | familia = [[Asteraceae]] | genus = ''[[Helianthus]]'' | species = '''''H. annuus''''' | binomial = ''Helianthus annuus'' | binomial_authority = [[Carolus Linnaeus|L.]] }} The '''sunflower''' ('''''Helianthus annuus''''') is an [[annual plant]] native to the Americas in the family [[Asteraceae]], with a large flowering head ([[inflorescence]]). The stem of the flower can grow as high as 3 metres tall, with the flower head reaching up to 30 cm in diameter with the "large" seeds. The term "sunflower" is also used to refer to all plants of the [[genus]] ''[[Helianthus]]'', many of which are [[perennial plant]]s. ==Description== What is usually called the [[flower]] is actually a ''[[Head (botany)|head]]'' (formally ''composite flower'') of numerous flowers (''florets'') crowded together. The outer flowers are the ''pubic florets'' and can be [[yellow]], [[Maroon (colour)|maroon]], [[Orange (colour)|orange]], or other [[color]]s, and are sterile. The florets inside the circular head are called ''disc florets''. The disc florets mature into what are traditionally called "[[sunflower seed]]s," but are actually the [[fruit]] (an ''[[achene]]'') of the plant. The true seeds are encased in an inedible husk. The florets within this cluster are arranged spirally. Typically each floret is oriented toward the next by approximately the [[golden angle]], producing a pattern of interconnecting [[spiral]]s where the number of left spirals and the number of right spirals are successive [[Fibonacci number]]s. Typically, there are 34 spirals in 1 direction and 55 in the other; on a very large sunflower you may see 89 in one direction and 144 in the other. [[Image:Helianthus whorl.jpg|thumb|Sunflower head displaying florets in spirals of 34 and 55 around the outside]] ==Heliotropism== Sunflowers in the [[bud]] stage exhibit [[heliotropism]]. At sunrise, the faces of most sunflowers are turned towards the east. Over the course of the day, they move to track the sun from east to west, while at night they return to an eastward orientation. This motion is performed by motor cells in the [[pulvinus]], a flexible segment of the stem just below the bud. As the bud stage ends, the stem stiffens and the blooming stage is reached. Sunflowers in the blooming stage are not heliotropic anymore. The stem has frozen, typically in an eastward orientation. The stem and leaves lose their green color. The wild sunflower typically does not turn toward the sun; its flowering heads may face many directions when mature. However, the leaves typically exhibit some heliotropism. ==Cultivation and uses== [[Image:sunflower farm.jpg|thumb|240px|A sunflower farm near [[Mysore]], [[India]].]] [[Image:Sunflower head snack.jpg|thumb|240px|Sunflower heads sold as [[snack food|snack]]s in [[China]].]] The sunflower is native to the [[Americas]]. Current research shows that it may have been domesticated twice, first in [[Mexico]] and later in the middle [[Mississippi Valley]]. Alternatively, it may have been introduced northward from Mexico at an early date as corn ([[maize]]) had been. The evidence thus far is that the sunflower was first domesticated in Mexico by at least 2600 BC.<ref>University of Cincinnati (2008, April 29). Ancient Sunflower Fuels Debate About Agriculture In The Americas. ScienceDaily. Retrieved April 29, 2008, from [http://www.sciencedaily.com­ /releases/2008/04/080429075321.htm]</ref> The earliest known examples of a fully domesticated sunflower north of Mexico have been found in Tennessee and date back to around 2300 B.C. Many indigenous American peoples used the sunflower as the symbol of the sun deity, including the [[Aztec]]s and the [[Otomi]] of Mexico and the [[Tahuantinsuyu|Incas]] in [[South America]]. [[Gold]] images of the flower, as well as [[seed]]s, were taken back to [[Spain]] early in the 16th century. Some researchers argue that the Spaniards tried to suppress cultivation of the sunflower because of its association with solar religion and warfare.<ref>[http://newswise.com/articles/view/540200/ Sunflower Debate Ends in Mexico, Researchers Say] Newswise, Retrieved on June 26, 2008.</ref> To grow well, sunflowers need full sun. They grow best in fertile, moist, well-[[drainage|drained]] [[soil]] with a lot of [[mulch]]. In commercial planting, seeds are planted 45 cm (1.5') apart and 2.5 cm (1") deep. Sunflower "whole seed" (fruit) are sold as a snack food after roasting within heated ovens with or without salt added. Sunflowers can be processed into a [[peanut butter]] alternative, [[Sunbutter]], especially in [[China]], [[Russia]], the [[United States]], the [[Middle East]] and [[Europe]]. In [[Germany]], it is used together with [[rye]] [[flour]] to make ''Sonnenblumenkernbrot'' (literally: sunflower whole seed [[bread]]), which is quite popular in [[German-speaking Europe]]. It is also sold as food for [[bird]]s and can be used directly in cooking and [[salads]]. [[Sunflower oil]], extracted from the [[Sunflower seed|seeds]], is [[Cooking oil|used for cooking]], as a [[carrier oil]] and to produce [[margarine]] as well as and [[biodiesel]], for which it is less expensive than the [[olive]] product. A range of sunflower varieties exist with differing fatty acid compositions; some 'high oleic' types contain a higher level of healthy monounsaturated fats in their oil than even [[olive oil]]. During the 18th Century, the use of sunflower oil became very popular in Europe, particularly with members of the Russian Orthodox Church because sunflower oil was one of the few oils that was not prohibited during Lent. The cake remaining after the seeds have been processed for oil is used as a [[livestock]] feed. Some recently developed [[cultivar]]s have drooping heads. These cultivars are less attractive to [[Gardening|gardeners]] growing the flowers as [[ornamental plant]]s, but appeal to [[farmer]]s, because they reduce [[bird]] damage and losses from some [[phytopathology|plant disease]]s. Sunflowers also produce [[latex]] and are the subject of experiments to improve their suitability as an alternative crop for producing [[hypoallergenic]] [[rubber]]. Traditionally, many Native American groups included the sunflower as the "fourth sister" with the better known "three sisters" combination of [[corn]], [[beans]], and [[squash]] (Kuepper & Dodson, 2001 [[http://attra.ncat.org/attra-pub/complant.html]]). Annual species are often planted for their [[allelopathic]] properties. However, for commercial farmers growing commodity crops, the sunflower, like any other unwanted plant, is often considered a [[weed]]. Especially in the midwestern USA, wild (perennial) species are often found in corn and soybean fields and can have a negative impact on yields. ==Mathematical model== [[Image:SunflowerModel.svg|thumb|100px|Illustration of Vogel's model for ''n''=1..500 .]] A model for the pattern of [[floret]]s in the head of a sunflower was proposed by H Vogel. This is expressed in [[polar coordinates]] :<math>r = c \sqrt{n}</math>, :<math>\theta = n \times 137.5^{\circ}</math>, where θ is the angle, ''r'' is the radius or distance from the center, and ''n'' is the index number of the floret and ''c'' is a constant scaling factor. It is a form of [[Fermat's spiral]]. The angle 137.5° is related to the [[golden ratio]] and gives a close packing of florets. This model has been used to produce computer graphics representations of sunflowers. <ref>{{cite book | last =Prusinkiewicz | first =Przemyslaw | authorlink =Przemyslaw Prusinkiewicz | coauthors =[[Aristid Lindenmayer|Lindenmayer, Aristid]] | title =[[The Algorithmic Beauty of Plants]] | publisher =Springer-Verlag | date =1990 | location = | pages =101-107 | url =http://algorithmicbotany.org/papers/#webdocs | doi = | id = ISBN 978-0387972978 }}</ref> ==Size== Sunflowers most commonly grow to heights between 2.5 and 3.5 m (8 - 12[[Foot (unit of measure)|']]). Scientific literature reports, from 1567, that a 12 m (40'), traditional, single-head, sunflower plant was grown in [[Padua]]. The same seed lot grew almost 8 m (24') at other times and places (e.g. [[Madrid]]). Much more recent feats (past score years) of over 8 m (25') have been achieved in both [[Netherlands]] and [[Ontario]], [[Canada]]. ==Cultural usage== *The sunflower is the state flower of the U.S. state of [[Kansas]], and one of the city flowers of [[Kitakyushu]], [[Japan]]. *The sunflower is often used as a symbol of [[green ideology]], much as the red [[rose]] is a symbol of [[socialism]] or [[social democracy]]. The sunflower is also the symbol of the [[Vegan Society]]. *Subject of [[Van Gogh]]'s most famous [[still life]], [[Sunflowers (series of paintings)]] ==Varieties== *American Giant Hybrid *Arikara *Autumn Beauty *Aztec Sun *Black Oil *Dwarf Sunspot *Evening Sun *Giant Primrose *Indian Blanket Hybrid *Irish Eyes *Italian White *Kong Hybrid *Large Grey Stripe *Lemon Queen *Mammoth Sunflower *Mongolian Giant *Orange Sun *Red Sun *Ring of Fire *Rostov *Soraya *Sunny Hybrid *Taiyo *Tarahumara *Teady Bear *Titan *Valentine *Velvet Queen ==Other species== *The Maximillian sunflower (''Helianthus maximillianii'') is one of 38 species of [[perennial sunflower]] native to [[North America]]. The [[Land Institute]] and other breeding programs are currently exploring the potential for these as a perennial seed crop *The [[Jerusalem artichoke]] (''Helianthus tuberosa'') is related to the sunflower, another example of [[perennial sunflower]]. *The '''Mexican sunflower''' is ''Tithonia rotundifolia''. It is only very distantly related to North American sunflowers. *'''False sunflower''' refers to plants of the genus ''Heliopsis''. ==Gallery== <gallery> Image:Wilkesboro Sunflower.JPG|Sunflowers in [[Wilkesboro, North Carolina]] Image:Sunflower After Rain.jpg|Sunflower After the rain Image:Sunflowerswilting.jpg|Sunflowers in [[Manila, Philippines]] Image:Sunflower_Bumbebee.jpg|[[Bumble bee]] sampling [[Sunflower nectar]] image:Sunflowers.jpg|Sunflowers growing near [[Fargo, North Dakota]] Image:Sunflower DSC01056.jpg|Lone sunflower about 2 m (6&nbsp;ft, 6') tall Image:Sunflower seedlings.jpg|Sunflower seedlings, just three days after germination Image:Sunflower10094.jpg|Large [[Russia|Russian]] Sunflower Image:Sunflower-fruiting_head.jpg|Fruiting head Image:Sunflower_seeds.jpg|Sunflower seeds. Image:Red_sunflowers.jpg|Red sunflowers. Image:Sunflowergarden.JPG|Small Sunflower Image:SunFlower1.jpg|Sunflower Macro <!-- Deleted image removed: Image:SunflowerBehshahr.jpg|thumb|right|200px|Sunflower farm, near Behshahr, Iran --> Image:Extreme_close-up_of_sunflower_head.jpg|Extreme close-up of sunflower head in [[Istanbul]], [[Turkey]] Image:SunflowerAgainstBlueSky.jpg|Sunflower against a blue sky Image:Laitche-P029.jpg|Sunflower in Japan. </gallery> {{-}} ==See also== *[[wikt:sheller|Sheller]] *[[Sunflower oil]] *[[Red sunflower]] ==Notes== <div class="references-small"><references/></div> == References == *Pope, Kevin; Pohl, Mary E. D.; Jones, John G.; Lentz, 3 David L.; von Nagy, Christopher; Vega, Francisco J.; Quitmyer Irvy R.; "[http://www.sciencemag.org/cgi/content/full/292/5520/1370 Origin and Environmental Setting of Ancient Agriculture in the Lowlands of Mesoamerica]," ''[[Science (journal)|Science]]'', 18 May 2001:Vol. 292. no. 5520, pp. 1370 - 1373. * Shosteck, Robt. 1974. ''Flowers and Plants. An International Lexicon with Biographical Notes''. Quadrangle/The New York Times Book Co. 329 pp. * Wood, Marcia. June 2002. "Sunflower Rubber?" Agricultural Research. USDA. [http://www.ars.usda.gov/is/AR/archive/jun02/rubber0602.htm] == External links == *[http://www.sunflowernsa.com/ National Sunflower Association] *[http://www.sunflowerocit.com/ Sunflower History] *[http://www.alonshepon.com/sunflowergal.html Metaphoric Sunflower in Arts] [[Category:Asteraceae]] [[Category:Crops originating from the Americas]] [[Category:Native crops of the United States]] [[Category:Edible nuts and seeds]] [[Category:Energy crops]] [[Category:Flowers]] [[Category:Medicinal plants]] <!-- interwiki --> [[ar:عباد الشمس]] [[ast:Mirasol]] [[bg:Слънчоглед]] [[ca:Gira-sol]] [[cs:Slunečnice roční]] [[da:Almindelig Solsikke]] [[de:Sonnenblume]] [[eo:Sunfloro]] [[es:Helianthus annuus]] [[fa:گل آفتابگردان]] [[fi:Auringonkukka]] [[fr:Tournesol]] [[gl:Xirasol]] [[he:חמנית]] [[hr:Suncokret]] [[hu:Napraforgó]] [[id:Bunga Matahari]] [[it:Helianthus annuus]] [[ja:ヒマワリ]] [[ko:해바라기]] [[la:Helianthus annuus]] [[lv:Saulgrieze]] [[ms:Pokok Bunga Matahari]] [[nds-nl:Zunnebloeme]] [[nl:Zonnebloem]] [[no:Solsikke]] [[pl:Słonecznik zwyczajny]] [[pt:Girassol]] [[ru:Подсолнух]] [[scn:Helianthus annuus]] [[simple:Sunflower]] [[sr:Сунцокрет]] [[sv:Solros]] [[th:ทานตะวัน]] [[tr:Ayçiçeği]] [[ug:ئاپتاپپەرەس]] [[uk:Соняшник]] [[vi:Hướng dương]] [[zh:向日葵]] [[zh-classical:向日葵]]