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{{Speciesbox
{{Speciesbox
|image = Centaurea cyanus 3.jpg
| image = Centaurea cyanus scan.jpg
| image_caption =
⚫
|image_caption = ''Centaurea cyanus'' (introduced species) near [[Peshastin, Washington|Peshastin]], Chelan County, Washington
|genus = Centaurea
| genus = Centaurea
|species = cyanus
| species = cyanus
|authority = [[Carl Linnaeus|L.]]
| authority = [[Carl Linnaeus|L.]]
}}
}}
⚫
[[File:Centaurea cyanus 3.jpg|thumb|''Centaurea cyanus'' (introduced species) near [[Peshastin, Washington|Peshastin]], Chelan County, Washington]]

'''''Centaurea cyanus''''', commonly known as '''cornflower''' or '''bachelor's button,'''{{refn|group=note|Other names include '''bluebottle''', '''bluecap''', '''blue blob''', '''blue bonnet''', '''cornbottle''', '''boutonierre flower''', '''hurtsickle''', and '''gogglebuster'''.<ref>Rosamond Richardson, 2017, ''Britain's Wildflowers.'' Pavilion.</ref><ref>{{cite book|last=Grigson|first=Geoffrey|author-link=Geoffrey Grigson|title=The Englishman's Flora|year=1975|publisher=Paladin|location=Frogmore|isbn=0586082093|page=419}}</ref>}} is an annual [[flowering plant]] in the family [[Asteraceae]] native to Europe. In the past, it often grew as a [[weed]] in cornfields (in the broad sense of "corn", referring to [[Food grain|grains]], such as wheat, barley, rye, or oats), hence its name. It is now [[endangered species|endangered]] in its native habitat by [[agriculture|agricultural intensification]], particularly by over-use of [[herbicide]]s. However, ''Centaurea cyanus'' is now also [[naturalisation (biology)|naturalised]] in many other parts of the world, including North America and parts of Australia through introduction as an [[ornamental plant]] in gardens and as a seed contaminant in crop seeds.<ref>[https://www.dayliliesinaustralia.com.au/cornflower-plant-caring-for-bachelors-button/]. ''Daylilies in Australia'', May 17, 2021</ref>
'''''Centaurea cyanus''''', commonly known as '''cornflower''' or '''bachelor's button''',{{refn|group=note|Other names include '''bluebottle''', '''bluecap''', '''blue blob''', '''blue bonnet''', '''cornbottle''', '''boutonierre flower''', '''hurtsickle''', and '''gogglebuster'''.<ref>Rosamond Richardson, 2017, ''Britain's Wildflowers.'' Pavilion.</ref><ref>{{cite book|last=Grigson|first=Geoffrey |author-link=Geoffrey Grigson|title=The Englishman's Flora|year=1975|publisher=Paladin|location=Frogmore|isbn=0586082093|page=419}}</ref>}} is an annual [[flowering plant]] in the family [[Asteraceae]] native to Europe. In the past, it often grew as a [[weed]] in cornfields (in the broad sense of "corn", referring to [[Food grain|grains]], such as wheat, barley, rye, or oats), hence its name. It is now [[endangered species|endangered]] in its native habitat by [[agriculture|agricultural intensification]], particularly by over-use of [[herbicide]]s. However, ''Centaurea cyanus'' is now also [[naturalisation (biology)|naturalised]] in many other parts of the world, including North America and parts of Australia through introduction as an [[ornamental plant]] in gardens and as a seed contaminant in crop seeds.<ref>[https://www.dayliliesinaustralia.com.au/cornflower-plant-caring-for-bachelors-button/]. ''Daylilies in Australia'', May 17, 2021</ref>


==Description==
==Description==
[[File:EB 1911 Flowering shoot of Cornflower.png|thumb|Flowering shoot of cornflower.<br> I. Disk-[[floret]] in vertical section]]
[[File:EB 1911 Flowering shoot of Cornflower.png|thumb|left|Flowering shoot of cornflower.<br> I. Disk-[[floret]] in vertical section]]
''Centaurea cyanus'' is an [[annual plant]] growing to 40–90&nbsp;cm tall, with grey-green branched stems. The leaves are lanceolate and 1–4&nbsp;cm long. The flowers are most commonly an intense blue colour and arranged in [[inflorescence|flowerheads]] (capitula) of 1.5–3&nbsp;cm diameter, with a ring of a few large, spreading ray [[floret]]s surrounding a central cluster of disc florets. The blue pigment is [[protocyanin]], which in roses is red.<ref>{{cite journal | title=Structure of the blue cornflower pigment | journal=Nature |vauthors=Shiono M, Matsugaki N, Takeda K | year=2005 | page=791 | volume=436 | doi=10.1038/436791a | pmid=16094358 | issue=7052| s2cid=4312804 }}</ref> Fruits are approx. 3.5&nbsp;mm long with 2–3&nbsp;mm long [[Pappus (botany)|pappus]] bristles.<ref>{{cite book |last1=Lauber |first1=Konrad |last2=Wagner |first2=Gerhart |title=Flora Helvetica |date=1996 |publisher=Paul Haupt Verlag |location=Berne |isbn=3-258-05405-3 |page=1152 |language=de}}</ref> It flowers all summer.<ref name="The Wild Flower Key">{{cite book| last = Rose| first = Francis| author-link = Francis Rose| title = The Wild Flower Key| year = 1981| publisher = Frederick Warne & Co| isbn = 0-7232-2419-6| pages = 386–387 }}</ref>
''Centaurea cyanus'' is an [[annual plant]] growing to {{Convert|20–100|cm|0}} tall, with grey-green branched stems. The leaves are lanceolate and {{Cvt|3–10|cm|0}} long.<ref name="FNA">{{cite web |last1=Keil |first1=David J. |last2=Ochsmann |first2=Jörg |title=''Centaurea cyanus'' - FNA |url=http://floranorthamerica.org/Centaurea_cyanus |website=Flora of North America |access-date=18 June 2024 |date=5 November 2020}}</ref> The flowers are most commonly an intense blue colour and arranged in [[inflorescence|flowerheads]] (capitula) of 1.5–3&nbsp;cm diameter, with a ring of a few large, spreading ray [[floret]]s surrounding a central cluster of disc florets. The blue pigment is [[protocyanin]], which in roses is red.<ref>{{cite journal | title=Structure of the blue cornflower pigment | journal=Nature |vauthors=Shiono M, Matsugaki N, Takeda K | year=2005 | page=791 | volume=436 | doi=10.1038/436791a | pmid=16094358 | issue=7052| s2cid=4312804 | doi-access=free }}</ref> Fruits are approx. 3.5&nbsp;mm long with 2–3&nbsp;mm-long [[Pappus (botany)|pappus]] bristles.<ref>{{cite book |last1=Lauber |first1=Konrad |last2=Wagner |first2=Gerhart |title=Flora Helvetica |date=1996 |publisher=Paul Haupt Verlag |location=Berne |isbn=3-258-05405-3 |page=1152 |language=de}}</ref> It flowers all summer.<ref name="The Wild Flower Key">{{cite book| last = Rose| first = Francis| author-link = Francis Rose| title = The Wild Flower Key| year = 1981| publisher = Frederick Warne & Co| isbn = 0-7232-2419-6| pages = 386–387 }}</ref>


==Distribution==
=== Genetics ===
⚫
''Centaurea cyanus'' is a [[Ploidy|diploid]] flower (2n = 24).<ref>Martin E., Dinç M., Duran A. (2009). "Karyomorphological Study of Eight Centaurea L. Taxa (Asteraceae) from Turkey". ''Turkish Journal of Botany'' '''33''':97–104.</ref> The genetic diversity within populations is high, although there could be a future decline in diversity due to [[population fragmentation]] and intensive agriculture.<ref>Le Corre V., Bellanger S., Guillemin J.-P., Darmency H. (2014). "Genetic diversity of the declining arable plant Centaurea cyanus: Population fragmentation within an agricultural landscape is not associated with enhanced spatial genetic structure". ''Weed Research'' '''54''':436–444.</ref> In general, ''Centaurea cyanus'' is a [[self-incompatible]] species. However, [[self-pollination|selfing]] still occurs occasionally, but results in [[inbreeding depression]].<ref>{{cite journal |last1=Bellanger |first1=Solène |last2=Guillemin |first2=Jean-Philippe |last3=Touzeau |first3=Solène |last4=Darmency |first4=Henri |date=2015 |title=Variation of inbreeding depression in Centaurea cyanus L., a self-incompatible species |journal=Flora |volume=212 |pages=24–29 |doi=10.1016/j.flora.2015.02.003|bibcode=2015FMDFE.212...24B }}</ref>
[[File:Centaurea cyanus 015.jpg|thumb|left|Centaurea cyanus, [[Sainte-Anne-de-la-Pérade]], [[Quebec]], [[Canada]]]]

==Distribution and habitat==
''Centaurea cyanus'' is native to [[temperate]] Europe, but is widely naturalized outside its native range.
''Centaurea cyanus'' is native to [[temperate]] Europe, but is widely naturalized outside its native range.


It has been present in Britain and Ireland as an [[archaeophyte]] (ancient introduction) since the [[Iron Age]].<ref name=BSBI>{{cite web |title=Online atlas of the British & Irish flora: ''Centaurea cyanus'' (Cornflower) |url=https://www.brc.ac.uk/plantatlas/index.php?q=plant/lychnis-viscaria |publisher=Biological Records Centre and Botanical Society of Britain and Ireland |access-date=22 May 2016}}</ref> In the United Kingdom, it has declined from 264 sites to just 3 sites in the last 50 years.<ref name=UKBAP>{{cite web |url=http://www.ukbap.org.uk/UKPlans.aspx?ID=198 |title=Action plan for Centaurea cyanus |publisher=Ukbap.org.uk |access-date=2009-11-05 |url-status=dead |archive-url=https://web.archive.org/web/20090221122324/http://www.ukbap.org.uk/UKPlans.aspx?ID=198 |archive-date=2009-02-21 }}</ref> In reaction to this, the conservation charity [[Plantlife]] named it as one of 101 species it would actively work to bring 'back from the brink'.<ref name=Plantlife>{{cite web |authors=Gopher Systems Ltd, Pewsey, Wiltshire, UK - Web Design & Development in Southern England |url=http://www.plantlife.org.uk/index.html |title=Plantlife website |publisher=Plantlife.org.uk |access-date=2009-11-05 |url-status=dead |archive-url=https://web.archive.org/web/20100127055822/http://www.plantlife.org.uk/index.html <!-- archived URL is too indirect --> |archive-date=2010-01-27 }}</ref>
It has been present in Britain and Ireland as an [[archaeophyte]] (ancient introduction) since the [[Iron Age]].<ref name="BSBI">{{cite web |title=Online atlas of the British & Irish flora: ''Centaurea cyanus'' (Cornflower) |url=https://www.brc.ac.uk/plantatlas/index.php?q=plant/lychnis-viscaria |publisher=Biological Records Centre and Botanical Society of Britain and Ireland |access-date=22 May 2016}}</ref> In the United Kingdom, it has declined from 264 sites to just 3 sites in the last 50 years.<ref name="UKBAP">{{cite web |url=http://www.ukbap.org.uk/UKPlans.aspx?ID=198 |title=Action plan for Centaurea cyanus |publisher=Ukbap.org.uk |access-date=2009-11-05 |url-status=dead |archive-url=https://web.archive.org/web/20090221122324/http://www.ukbap.org.uk/UKPlans.aspx?ID=198 |archive-date=2009-02-21}}</ref>


In reaction to this, the conservation charity [[Plantlife]] named it as one of 101 species it would actively work to bring 'back from the brink'.<ref name="Plantlife">{{cite web |url=http://www.plantlife.org.uk/index.html |title=Plantlife website |publisher=Plantlife.org.uk |access-date=2009-11-05 |url-status=dead |archive-date=2010-01-27 |archive-url=https://web.archive.org/web/20100127055822/http://www.plantlife.org.uk/index.html <!-- archived URL is too indirect -->}}</ref>
⚫
In the [[County Clare]] ([[vice-county|VC]] H9) in [[Ireland]], ''Centaurea cyanus'' is recorded in arable fields as very rare and almost extinct,<ref name=Skeffington>{{cite journal |last=Skeffington |first=M.S. |date=2015 |title=Cornflower (''Centaurea cynanus'' L.) and Good-king-henry (''Chenopodium bonus-henricus'' L.) |journal=Irish Naturalists' Journal |volume=34 |pages=27–31 }}</ref> while in the North-East of Ireland, it was abundant before the 1930s.<ref name=Hackney>{{cite book |last=Hackney |first=P. |date=1992 |title=Stewart & Corry's Flora of the North-east of Ireland |edition=Third |publisher=Institute of Irish Studies and The Queen's University of Belfast |isbn=0-85389-446-9 }}
</ref>


⚫
In the [[County Clare]] ([[vice-county|VC]] H9) in [[Ireland]], ''C. cyanus'' is recorded in arable fields as very rare and almost extinct,<ref name="Skeffington">{{cite journal |last=Skeffington |first=M.S. |date=2015 |title=Cornflower (''Centaurea cynanus'' L.) and Good-king-henry (''Chenopodium bonus-henricus'' L.) |journal=Irish Naturalists' Journal |volume=34 |pages=27–31 }}</ref> while in northeast Ireland, it was abundant before the 1930s.<ref name="Hackney">{{cite book |last=Hackney |first=P. |date=1992 |title=Stewart & Corry's Flora of the North-east of Ireland |edition=Third |publisher=Institute of Irish Studies and The Queen's University of Belfast |isbn=0-85389-446-9}}</ref>
== Genetics and breeding ==
⚫
=== Genetics ===
⚫
''Centaurea cyanus'' is a [[Ploidy|diploid]] flower (2n = 24).<ref>Martin E., Dinç M., Duran A. (2009). "Karyomorphological Study of Eight Centaurea L. Taxa (Asteraceae) from Turkey". ''Turkish Journal of Botany'' '''33''':97–104.</ref> The genetic diversity within populations is high, although there could be a future decline in diversity due to [[population fragmentation]] and intensive agriculture.<ref>Le Corre V., Bellanger S., Guillemin J.-P., Darmency H. (2014). "Genetic diversity of the declining arable plant Centaurea cyanus: Population fragmentation within an agricultural landscape is not associated with enhanced spatial genetic structure". ''Weed Research'' '''54''':436–444.</ref> In general, ''Centaurea cyanus'' is a [[self-incompatible]] species. However, [[self-pollination|selfing]] still occurs occasionally, but results in [[inbreeding depression]].<ref>{{cite journal |last1=Bellanger |first1=Solène |last2=Guillemin |first2=Jean-Philippe |last3=Touzeau |first3=Solène |last4=Darmency |first4=Henri |title=Variation of inbreeding depression in Centaurea cyanus L., a self-incompatible species |journal=Flora |date=2015 |volume=212 |pages=24–29 |doi=10.1016/j.flora.2015.02.003}}</ref>

=== Cultivars ===
⚫
Several [[cultivar]]s of ''Centaurea cyanus'' with varying [[pastel colour]]s, including pink and purple, have been selected for ornamental purposes. The species is also grown for the cutflower industry in Canada for use by florists. Doubled blue [[cultivars]] (such as 'Blue Boy' or 'Blue Diadem') are most commonly used for this purpose, but white, pink, lavender and black (actually a very dark [[maroon]]) [[cultivars]] are also used, albeit to a lesser extent.

⚫
=== Breeding goals ===
⚫
As for all ornamental plants, important goals of ''Centaurea cyanus'' breeding include the induction of phenotypic variation (e.g. in flower coloration, size and shape, foliage characteristics or plant height), higher flower yield, resistance to pests and diseases as well as tolerance to abiotic stress (e.g., extreme temperatures, drought or salinity).<ref>{{cite web |title=Breeding and Seed Production of Ornamental Crops |url=http://ecoursesonline.iasri.res.in/mod/page/view.php?id=108944 |access-date=22 November 2020}}</ref>


== Ecology ==
== Ecology ==
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=== Fodder for insects and birds ===
=== Fodder for insects and birds ===
[[File:Bee on cornflower in Aspen (91223).jpg|thumb|A [[honey bee]] on a cornflower]]
[[File:Apis mellifera, France.jpg|thumb|A [[honey bee]] on a cornflower]]
The [[pollen]] of ''Centaurea cyanus'' is used by several different insect species. Insects of the orders [[Hymenoptera]] and [[Diptera]] are particularly attracted by the flower.<ref>Carreck N., Williams I. (2002). "Food for insect pollinators on farmland: insect visits to flowers of annual seed mixtures". Journal of Insect Conservation 6:13–23.</ref> As ''Centaurea cyanus'' is a [[self-incompatible]] species, it needs external [[pollination]]. The [[nectar]] of ''Centaurea cyanus'' is very sweet with a sugar content of 34%. Due to its high sugar production of up to 0.2&nbsp;mg sugar per day and flower, the species is highly appreciated by [[bee]]keepers.<ref>Helmut Horn, Cord Lüllmann: Das große Honigbuch, Kosmos, Stuttgart, 3. Auflage, 2006, {{ISBN|3-440-10838-4}}, S. 31</ref>
The [[pollen]] of ''Centaurea cyanus'' is used by several different insect species. Insects of the orders [[Hymenoptera]] and [[Diptera]] are particularly attracted by the flower.<ref>Carreck N., Williams I. (2002). "Food for insect pollinators on farmland: insect visits to flowers of annual seed mixtures". Journal of Insect Conservation 6:13–23.</ref> As ''Centaurea cyanus'' is a [[self-incompatible]] species, it needs external [[pollination]]. The [[nectar]] of ''Centaurea cyanus'' is very sweet with a sugar content of 34%. Due to its high sugar production of up to 0.2&nbsp;mg sugar per day and flower, the species is highly appreciated by [[bee]]keepers.<ref>Helmut Horn, Cord Lüllmann: Das große Honigbuch, Kosmos, Stuttgart, 3. Auflage, 2006, {{ISBN|3-440-10838-4}}, S. 31</ref>


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=== Control of insect pests ===
=== Control of insect pests ===
''Centaurea cyanus'' was found to produce volatiles attracting ''[[Microplitis]] mediator'',<ref>{{cite journal |last1=Belz |first1=Elodie |last2=Kölliker |first2=Mathias |last3=Balmer |first3=Oliver |title=Olfactory attractiveness of flowering plants to the parasitoid Microplitis mediator: potential implications for biological control |journal=BioControl |date=2013 |volume=58 |issue=2 |pages=163–173|doi=10.1007/s10526-012-9472-0 |s2cid=17117503 |url=http://doc.rero.ch/record/311439/files/10526_2012_Article_9472.pdf }}</ref> which is a major [[parasitoid]] of the cabbage moth (''[[Mamestra brassicae]]''), which is the most important pest of [[cabbage]] (''Brassica oleracea'') in central Europe. Planting ''Centaurea cyanus'' in cabbage fields as a [[Companion planting|companion plant]] was thus suggested as an alternative to the widespread use of [[insecticide]]s to control ''Mamestra brassicae''. Field experiments showed that planting ''Centaurea cyanus'' in cabbage fields at a density of 1 plant / m<sup>2</sup> can result in a significant increase in parasitation of ''Mamestra brassicae'' larvae, predation of ''Mamestra brassicae'' eggs (e.g. by [[carabid]] beetles or [[spiders]]) and ultimately cabbage yield.<ref>{{cite journal |last1=Balmer |first1=Oliver |last2=Géneau |first2=Céline E. |last3=Belz |first3=Elodie |last4=Weishaupt |first4=Bettina |last5=Förderer |first5=Gerda |last6=Moos |first6=Sebastian |last7=Ditner |first7=Nadine |last8=Juric |first8=Ivan |last9=Luka |first9=Henryk |title=Wildflower companion plants increase pest parasitation and yield in cabbage fields: Experimental demonstration and call for caution |journal=Biological Control |date=2014 |volume=76 |pages=19–27|doi=10.1016/j.biocontrol.2014.04.008 }}</ref>
''Centaurea cyanus'' was found to produce volatiles attracting ''[[Microplitis]] mediator'',<ref>{{cite journal |last1=Belz |first1=Elodie |last2=Kölliker |first2=Mathias |last3=Balmer |first3=Oliver |title=Olfactory attractiveness of flowering plants to the parasitoid Microplitis mediator: potential implications for biological control |journal=BioControl |date=2013 |volume=58 |issue=2 |pages=163–173|doi=10.1007/s10526-012-9472-0 |bibcode=2013BioCo..58..163B |s2cid=17117503 |url=http://doc.rero.ch/record/311439/files/10526_2012_Article_9472.pdf }}</ref> which is a major [[parasitoid]] of the cabbage moth (''[[Mamestra brassicae]]''), which is the most important pest of [[cabbage]] (''Brassica oleracea'') in central Europe. Planting ''Centaurea cyanus'' in cabbage fields as a [[Companion planting|companion plant]] was thus suggested as an alternative to the widespread use of [[insecticide]]s to control ''Mamestra brassicae''. Field experiments showed that planting ''Centaurea cyanus'' in cabbage fields at a density of 1 plant / m<sup>2</sup> can result in a significant increase in parasitation of ''Mamestra brassicae'' larvae, predation of ''Mamestra brassicae'' eggs (e.g. by [[carabid]] beetles or [[spiders]]) and ultimately cabbage yield.<ref>{{cite journal |last1=Balmer |first1=Oliver |last2=Géneau |first2=Céline E. |last3=Belz |first3=Elodie |last4=Weishaupt |first4=Bettina |last5=Förderer |first5=Gerda |last6=Moos |first6=Sebastian |last7=Ditner |first7=Nadine |last8=Juric |first8=Ivan |last9=Luka |first9=Henryk |title=Wildflower companion plants increase pest parasitation and yield in cabbage fields: Experimental demonstration and call for caution |journal=Biological Control |date=2014 |volume=76 |pages=19–27|doi=10.1016/j.biocontrol.2014.04.008 |bibcode=2014BiolC..76...19B }}</ref>


== Cultivation ==
== Cultivation ==
⚫
[[File:Bachelor's button, Basket flower, Boutonniere flower, Cornflower - 3.jpg|thumb]]
⚫
Several [[cultivar]]s of ''Centaurea cyanus'' with varying [[pastel colour]]s, including pink and purple, have been selected for ornamental purposes. The species is also grown for the [[cut flower industry]] in Canada for use by florists. Doubled blue [[cultivars]] (such as 'Blue Boy' or 'Blue Diadem') are most commonly used for this purpose, but white, pink, lavender and black (actually a very dark [[maroon]]) [[cultivars]] are also used, albeit to a lesser extent. There are varieties with blue, white, purple, pink or even black petals.

⚫
=== Breeding goals ===
⚫
As for all ornamental plants, important goals of ''Centaurea cyanus'' breeding include the induction of phenotypic variation (e.g. in flower coloration, size and shape, foliage characteristics or plant height), higher flower yield, resistance to pests and diseases as well as tolerance to abiotic stress (e.g., extreme temperatures, drought or salinity).<ref>{{cite web |title=Breeding and Seed Production of Ornamental Crops |url=http://ecoursesonline.iasri.res.in/mod/page/view.php?id=108944 |access-date=22 November 2020}}</ref>
=== Soil and climate requirements ===
=== Soil and climate requirements ===
''Centaurea cyanus'' requires full sun and neutral (pH 6.6–7.5) to mildly alkaline (pH 7.6–7.8), moist and well-drained [[soil]]. However, ''Centaurea cyanus'' is quite tolerant to drought once established.<ref name=":1">{{cite web|title=How to Grow Cornflower|url=https://www.americanmeadows.com/wildflower-seeds/cornflower-seeds/how-to-grow-cornflower|access-date=5 November 2020|website=American Meadows}}</ref>
''Centaurea cyanus'' requires full sun and neutral (pH 6.6–7.5) to mildly alkaline (pH 7.6–7.8), moist and well-drained [[soil]]. However, ''Centaurea cyanus'' is quite tolerant to drought once established.<ref name=":1">{{cite web|title=How to Grow Cornflower|url=https://www.americanmeadows.com/wildflower-seeds/cornflower-seeds/how-to-grow-cornflower|access-date=5 November 2020|website=American Meadows}}</ref>
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==Uses==
==Uses==
===Food===
===Culinary===
[[File:005 Cornflower petals - edible flower on ice cream.jpg|thumb|Raw cornflower petals used as a dessert decoration ingredient on strawberry ice cream]]
[[File:005 Cornflower petals - edible flower on ice cream.jpg|thumb|Raw cornflower petals used as a dessert decoration ingredient on strawberry ice cream]]
The flowers of ''Centaurea cyanus'' can be eaten raw, dried or cooked.<ref>Rop O., Mlcek J., Jurikova T., Neugebauerová J., Vabkova J. (2012). "Edible Flowers-A New Promising Source of Mineral Elements in Human Nutrition". ''Molecules'' '''17''':6672–83.</ref> Dried [[petal]]s are used in foods, including in spices. Their main purpose is to add colour to food. There are cheeses or oils that contain raw petals. Petals can also be added to salads, drinks, or desserts for garnishing purposes in raw or dried form.
The flowers of ''Centaurea cyanus'' can be eaten raw, dried or cooked.<ref>Rop O., Mlcek J., Jurikova T., Neugebauerová J., Vabkova J. (2012). "Edible Flowers-A New Promising Source of Mineral Elements in Human Nutrition". ''Molecules'' '''17''':6672–83.</ref> Dried [[petal]]s are used in foods, including in spices. Their main purpose is to add colour to food. There are cheeses or oils that contain raw petals. Petals can also be added to salads, drinks, and desserts for garnishing purposes in raw or dried form.


===Beverages===
Dried petals are also used in teas and other beverages. Blue cornflower petals are sometimes one of the ingredients in [[Lady Grey (tea)|Lady Grey tea]].<ref>{{cite web | url=https://www.twinings.co.uk/gifts/discovery-collection/orangery-of-lady-grey-pyramid | title=Discovery Collection Orangery of Lady Grey - 15 Pyramid Tea Bags }}</ref>
Dried petals are also used in teas and other beverages. Blue cornflower petals are sometimes one of the ingredients in [[Lady Grey (tea)|Lady Grey tea]].<ref>{{cite web | url=https://www.twinings.co.uk/gifts/discovery-collection/orangery-of-lady-grey-pyramid | title=Discovery Collection Orangery of Lady Grey - 15 Pyramid Tea Bags }}</ref>


===Ornamental use===
===Medicine===
''Centaurea cyanus'' is used as an ornamental plant. There are varieties with blue, white, purple, pink or even black petals.

===Pigment===
⚫
The blue color of ''Centaurea cyanus'' is due to [[protocyanin]], an [[anthocyanin]] pigment that is also found in roses.<ref>Shiono M., Matsugaki N., Takeda K. (2005). "Structure of the blue cornflower pigment". ''Nature'' '''436''':791–791.</ref> Different [[anthocyanin]]s derived from ''Centaurea cyanus'' are used as natural additives in food products, such as yoghurts.

===Medicinal purpose===
''Centaurea cyanus'' contains a wide range of pharmacologically active compounds, such as [[flavonoid]]s, [[anthocyanin]]s and [[aromatic acid]]s.<ref>Al-Snafi A. (2015). "The pharmacological importance of Centaurea cynus - A review". ''International Journal of Pharmacy Review and Research'' '''5:'''379–384.</ref> Especially the flower head finds application in herbal medicine, but leaves and seeds are also used for pharmacological purposes, albeit to a lesser extent.
''Centaurea cyanus'' contains a wide range of pharmacologically active compounds, such as [[flavonoid]]s, [[anthocyanin]]s and [[aromatic acid]]s.<ref>Al-Snafi A. (2015). "The pharmacological importance of Centaurea cynus - A review". ''International Journal of Pharmacy Review and Research'' '''5:'''379–384.</ref> Especially the flower head finds application in herbal medicine, but leaves and seeds are also used for pharmacological purposes, albeit to a lesser extent.


In particular, extracts from the flower heads have anti-inflammatory properties used in the treatment of minor [[ocular]] [[inflammation]]s.<ref>Garbacki N., Gloaguen V., Damas J., Bodart P., Tits M., Angenot L. (1999). "Anti-inflammatory and immunological effects of Centaurea cyanus flower-heads". ''Journal of ethnopharmacology'' '''68''':235–241.</ref> [[Antioxidant]] properties are high due to [[Vitamin C|ascorbic acid]] and [[Phenolic acid|phenolic]] compounds.<ref>Lockowandt L., Pinela J., Roriz C., Pereira C., Abreu R., Calhelha R., Alves M., Barros L., Bredol M., Ferreira I. (2019). "Chemical features and bioactivities of cornflower (Centaurea cyanus L.) capitula: The blue flowers and the unexplored non-edible part". ''Industrial Crops and Products'' '''128''':496–503.</ref> Furthermore, extracts of the flower head and vegetative parts of the plant were shown to have [[Stomach|gastroprotective]] effects due to their content of [[quercetin]], [[apigenin]] and [[caffeic acid]] derivates.<ref>Pirvu L., Dragomir C., Schiopu S., Mihul S. (2012). "Vegetal extracts with gastroprotective activity. Part. I. Extracts obtained from Centaurea cyanus L. raw material". ''Romanian Biotechnological Letters'' '''17''':7169-7176.</ref>
In particular, extracts from the flower heads have anti-inflammatory properties used in the treatment of minor [[ocular]] [[inflammation]]s.<ref>Garbacki N., Gloaguen V., Damas J., Bodart P., Tits M., Angenot L. (1999). "Anti-inflammatory and immunological effects of Centaurea cyanus flower-heads". ''Journal of ethnopharmacology'' '''68''':235–241.</ref> [[Antioxidant]] properties are high due to [[Vitamin C|ascorbic acid]] and [[Phenolic acid|phenolic]] compounds.<ref>Lockowandt L., Pinela J., Roriz C., Pereira C., Abreu R., Calhelha R., Alves M., Barros L., Bredol M., Ferreira I. (2019). "Chemical features and bioactivities of cornflower (Centaurea cyanus L.) capitula: The blue flowers and the unexplored non-edible part". ''Industrial Crops and Products'' '''128''':496–503.</ref> Furthermore, extracts of the flower head and vegetative parts of the plant were shown to have [[Stomach|gastroprotective]] effects due to their content of [[quercetin]], [[apigenin]] and [[caffeic acid]] derivates.<ref>Pirvu L., Dragomir C., Schiopu S., Mihul S. (2012). "Vegetal extracts with gastroprotective activity. Part. I. Extracts obtained from Centaurea cyanus L. raw material". ''Romanian Biotechnological Letters'' '''17''':7169-7176.</ref>

⚫
=== Pigment ===
⚫
The blue color of ''Centaurea cyanus'' is due to [[protocyanin]], an [[anthocyanin]] pigment that is also found in roses.<ref>Shiono M., Matsugaki N., Takeda K. (2005). "Structure of the blue cornflower pigment". ''Nature'' '''436''':791–791.</ref> Different anthocyanins derived from ''Centaurea cyanus'' are used as natural additives in food products, such as yoghurts.


=== Phytoremediation ===
=== Phytoremediation ===
''Centaurea cyanus'' has been evaluated for [[phytoremediation]] of soils contaminated with [[lead]]. Inoculation of the contaminated soil with ''Glomus spp.'' (fungus) and ''[[Pseudomonas]] spp.'' (bacterium) would significantly enhance the biomass production and lead uptake of ''Centaurea cyanus''.<ref>{{cite journal |last1=Karimi |first1=Akbar |last2=Khodaverdiloo |first2=Habib |last3=Rasouli-Sadaghiani |first3=Habib |title=Microbial-Enhanced Phytoremediation of Lead Contaminated Calcareous Soil by Centaurea cyanus L. |journal=CLEAN - Soil Air Water |date=2018 |volume=46 |issue=2 |doi=10.1002/clen.201700665}}</ref>
''Centaurea cyanus'' has been evaluated for [[phytoremediation]] of soils contaminated with [[lead]]. Inoculation of the contaminated soil with ''Glomus spp.'' (fungus) and ''[[Pseudomonas]] spp.'' (bacterium) would significantly enhance the biomass production and lead uptake of ''Centaurea cyanus''.<ref>{{cite journal |last1=Karimi |first1=Akbar |last2=Khodaverdiloo |first2=Habib |last3=Rasouli-Sadaghiani |first3=Habib |title=Microbial-Enhanced Phytoremediation of Lead Contaminated Calcareous Soil by Centaurea cyanus L. |journal=CLEAN - Soil, Air, Water |date=2018 |volume=46 |issue=2 |doi=10.1002/clen.201700665|bibcode=2018CSAW...4600665K }}</ref>


==In culture==
==Folklore and symbolism==
[[File:EKRE logo.png|thumb|Logo of the [[Conservative People's Party of Estonia]]]]
[[File:Keila vapp.svg|thumb|upright|Cornflower pictured in the coat of arms of [[Keila]]]]
⚫
[[File:Bachelor's button, Basket flower, Boutonniere flower, Cornflower - 3.jpg|thumb]]
[[File:Keila vapp.svg|thumb|Cornflower pictured in the coat of arms of [[Keila]]]]


In folklore, cornflowers were worn by young men in love;{{clarify|date=March 2022}} if the flower faded too quickly, it was taken as a sign that the man's love was not returned.<ref name=Century>{{cite book |last=Howard |first=Michael |title=Traditional Folk Remedies |publisher=Century |date=1987 }}</ref>{{rp|126}}
In folklore, cornflowers were worn by young men in love;{{clarify|date=March 2022}} if the flower faded too quickly, it was taken as a sign that the man's love was not returned.<ref name=Century>{{cite book |last=Howard |first=Michael |title=Traditional Folk Remedies |publisher=Century |date=1987 }}</ref>{{rp|126}}


The blue cornflower was one of the national symbols of Germany.<ref name=Cleene>{{cite book|last1=Cleene|first1=Marcel|first2=Marie Claire|last2=Lejeune|title=Compendium of Symbolic and Ritual Plants in Europe: Herbs|url=https://books.google.com/books?id=g5GBAAAAMAAJ| year=2002| publisher=Man & Culture|isbn=9789077135044| quote=The Cornflower was once the floral emblem of Germany (hence the German common name Kaiserblume). }}</ref> This is partly due to the story that when [[Queen Louise of Prussia]] was fleeing Berlin and pursued by [[Napoleon]]'s forces, she hid her children in a field of cornflowers and kept them quiet by weaving wreaths for them from the flowers. The flower thus became identified with [[Prussia]], not least because it was the same color as the Prussian military uniform.<ref>{{cite book| last = Reid| first = Marilyn| title = Mythical Flower Stories| url = https://books.google.com/books?id=eZvw84yGFecC&pg=PA40| year = 2007| publisher = Lulu.com| isbn = 978-1-84753-521-4| page = 40 }}</ref> After the unification of Germany in 1871, it went on to become a symbol of the country as a whole. For this reason, in [[Austria]] the blue cornflower is a political symbol for [[pan-German]] and [[rightist]] ideas.<ref>{{Cite book |first=Andrew G. |last=Whiteside |title=Pan-Germanism: Anti-Semitism in Mass-Style Politics |work=Current Research on Anti-Semitism: Hostages of Modernization |volume=3/2 |publisher=de Gruyter |year=1993 |page=691}}</ref><ref>{{Cite book |first=Daniel L. |last=Unowsky |title=The Pomp and Politics of Patriotism: Imperial Celebrations in Habsburg Austria, 1848–1916 |url=https://archive.org/details/pomppoliticspatr00unow |url-access=limited |publisher=Purdue University Press |year=2005 |page=[https://archive.org/details/pomppoliticspatr00unow/page/n171 157]|isbn=9781557534002 }}</ref> It was worn as a secret symbol identifying members of the then-illegal [[Nazi Party|NSDAP]] in Austria in the 1930s.<ref>{{Cite web|url=https://www.ris.bka.gv.at/Dokumente/Vfgh/JFT_10029384_96B02211_00/JFT_10029384_96B02211_00.html|title=RIS Dokument|website=www.ris.bka.gv.at|language=de|access-date=2018-03-24}}</ref><ref>[https://www.theguardian.com/world/2019/jan/11/new-far-right-german-party-adopts-former-secret-nazi-symbol New far-right German party adopts former secret Nazi symbol] The Guardian, 2019</ref> Members of the [[Freedom Party of Austria|Freedom Party]] wore it at the openings of the Austrian parliament since 2006.<ref>{{Cite news |title=Anklänge an illegale NSDAPler |publisher=ORF.at |url=http://newsv1.orf.at/061030-5431/index.html |date=30 October 2006}}</ref><ref>{{Cite web|url=http://www.kpoe.at/home/aktuelles/2008/2008-mit-kornblume-zur-angelobung-ins-oesterreichische-parlament|title=KPÖ|website=www.kpoe.at|language=de|access-date=2018-03-24}}</ref><ref>{{Cite news|url=http://www.oe24.at/oesterreich/politik/Wirbel-um-Nazi-Blume-bei-der-FPOe/120569202|title=Wirbel um Nazi-Blume bei der FPÖ|date=2013-10-29|access-date=2018-03-24}}</ref> After the last general election 2017 they replaced it with the [[Leontopodium nivale|edelweiss]].<ref>{{Cite news|url=https://kurier.at/politik/inland/fpoe-mandatare-tragen-heute-edelweiss-statt-kornblume/297.137.849|title=FPÖ-Mandatare tragen heute Edelweiß statt Kornblume|access-date=2018-03-24}}</ref>
The blue cornflower was one of the national symbols of Germany.<ref name=Cleene>{{cite book| last1=Cleene| first1=Marcel| first2=Marie Claire| last2=Lejeune| title=Compendium of Symbolic and Ritual Plants in Europe: Herbs| url=https://books.google.com/books?id=g5GBAAAAMAAJ| year=2002| publisher=Man & Culture| isbn=9789077135044| quote=The Cornflower was once the floral emblem of Germany (hence the German common name Kaiserblume).}}</ref> This is partly due to the story that when [[Queen Louise of Prussia]] was fleeing Berlin and pursued by [[Napoleon]]'s forces, she hid her children in a field of cornflowers and kept them quiet by weaving wreaths for them from the flowers. The flower thus became identified with [[Prussia]], not least because it was the same color as the Prussian military uniform.<ref>{{cite book| last=Reid| first=Marilyn| year=2007| title=Mythical Flower Stories| url=https://books.google.com/books?id=eZvw84yGFecC&pg=PA40| publisher=Lulu.com| isbn=978-1-84753-521-4| page=40}}</ref> After the unification of Germany in 1871, it went on to become a symbol of the country as a whole. For this reason, in [[Austria]] the blue cornflower is a political symbol for [[pan-German]] and [[rightist]] ideas.<ref>{{Cite book |first=Andrew G. |last=Whiteside |title=Pan-Germanism: Anti-Semitism in Mass-Style Politics |work=Current Research on Anti-Semitism: Hostages of Modernization |volume=3/2 |publisher=de Gruyter |year=1993 |page=691}}</ref><ref>{{Cite book |first=Daniel L. |last=Unowsky |year=2005 |title=The Pomp and Politics of Patriotism: Imperial Celebrations in Habsburg Austria, 1848–1916 |page=[https://archive.org/details/pomppoliticspatr00unow/page/n171 157]|publisher=Purdue University Press|isbn=9781557534002 |url=https://archive.org/details/pomppoliticspatr00unow |url-access=limited}}</ref> It was worn as a secret symbol identifying members of the then-illegal [[Nazi Party|NSDAP]] in Austria in the 1930s.<ref>{{Cite web |url=https://www.ris.bka.gv.at/Dokumente/Vfgh/JFT_10029384_96B02211_00/JFT_10029384_96B02211_00.html|title=RIS Dokument |website=www.ris.bka.gv.at|language=de|access-date=2018-03-24}}</ref><ref>{{cite news |author=Josie Le Blond |url=https://www.theguardian.com/world/2019/jan/11/new-far-right-german-party-adopts-former-secret-nazi-symbol |title=New far-right German party adopts former secret Nazi symbol |work=The Guardian |date=11 Jan 2019}}</ref> Members of the [[Freedom Party of Austria|Freedom Party]] wore it at the openings of the Austrian parliament since 2006.<ref>{{Cite news |title=Anklänge an illegale NSDAPler |publisher=ORF.at |url=http://newsv1.orf.at/061030-5431/index.html |date=30 October 2006}}</ref><ref>{{Cite web |url=http://www.kpoe.at/home/aktuelles/2008/2008-mit-kornblume-zur-angelobung-ins-oesterreichische-parlament |title=KPÖ |website=www.kpoe.at |language=de |access-date=2018-03-24 |archive-date=25 March 2018 |archive-url=https://web.archive.org/web/20180325105802/http://www.kpoe.at/home/aktuelles/2008/2008-mit-kornblume-zur-angelobung-ins-oesterreichische-parlament |url-status=dead }}</ref><ref>{{Cite news |title=Wirbel um Nazi-Blume bei der FPÖ |date=2013-10-29 |url=http://www.oe24.at/oesterreich/politik/Wirbel-um-Nazi-Blume-bei-der-FPOe/120569202|access-date=2018-03-24}}</ref> After the last general election 2017 they replaced it with the [[Leontopodium nivale|edelweiss]].<ref>{{Cite news |title=FPÖ-Mandatare tragen heute Edelweiß statt Kornblume |url=https://kurier.at/politik/inland/fpoe-mandatare-tragen-heute-edelweiss-statt-kornblume/297.137.849 |access-date=2018-03-24}}</ref>


It was also the favourite flower of Louise's son [[Kaiser Wilhelm I]].<ref name=Coulter>{{cite book| last = Coulter| first = Lynn| title = Gardening with Heirloom Seeds: Tried-and-True Flowers, Fruits, and Vegetables for a New Generation| url = https://books.google.com/books?id=ktF6PfQcDcYC&pg=PA165| year = 2009| publisher = ReadHowYouWant.com, Limited| isbn = 978-1-4587-2217-1| page = 165 }}</ref> Because of its ties to royalty, authors such as [[Theodor Fontane]] have used it symbolically, often sarcastically, to comment on the social and political climate of the time.{{Citation needed|date=January 2009}}
It was also the favourite flower of Louise's son [[Kaiser Wilhelm I]].<ref name=Coulter>{{cite book| last=Coulter| first=Lynn| title=Gardening with Heirloom Seeds: Tried-and-True Flowers, Fruits, and Vegetables for a New Generation| url=https://books.google.com/books?id=ktF6PfQcDcYC&pg=PA165| year=2009| publisher=ReadHowYouWant.com, Limited| isbn=978-1-4587-2217-1| page=165}}</ref> Because of its ties to royalty, authors such as [[Theodor Fontane]] have used it symbolically, often sarcastically, to comment on the social and political climate of the time.{{Citation needed|date=January 2009}}


The cornflower is also often seen as an inspiration for the German [[Romanticism|Romantic]] symbol of the [[Blue Flower]].{{Citation needed|date=January 2009}}
The cornflower is also often seen as an inspiration for the German [[Romanticism|Romantic]] symbol of the [[Blue Flower]].{{Citation needed|date=January 2009}}
Line 109: Line 101:
Due to its traditional association with Germany, the cornflower has been made the official symbol of the annual German-American [[Steuben Parade]].
Due to its traditional association with Germany, the cornflower has been made the official symbol of the annual German-American [[Steuben Parade]].


[[File:EKRE logo.png|thumb|upright|Logo of the [[Conservative People's Party of Estonia]]]]
The blue cornflower has been the national flower of [[Estonia]] since 1969 and symbolizes daily bread to Estonians. It is also the symbol of the Estonian [[Conservative People's Party of Estonia|Conservative People's Party]].
The blue cornflower has been the national flower of [[Estonia]] since 1969 and symbolizes daily bread to Estonians. It is also the symbol of the Estonian [[Conservative People's Party of Estonia|Conservative People's Party]].


Line 115: Line 108:
It is the official flower of the Swedish province of [[Östergötland]] and the school flower of [[Winchester College]] and also of [[Dulwich College]], where it is said to have been the favourite flower of the founder, [[Edward Alleyn]].
It is the official flower of the Swedish province of [[Östergötland]] and the school flower of [[Winchester College]] and also of [[Dulwich College]], where it is said to have been the favourite flower of the founder, [[Edward Alleyn]].


In France the {{lang|fr|[[bleuet de France]]}} is the symbol of the [[Armistice with Germany (Compiègne)|11 November 1918]] [[armistice]] and, as such, a common symbol for [[veterans]] (especially the now defunct [[poilus]] of [[World War I]]), similar to the [[Remembrance poppy|Remembrance poppies]] worn in the United Kingdom and in Canada.<ref>{{cite web |url=http://www.bleuetdefrance.fr/ |title=Le Bleuet de France - Page d'accueil |publisher=Bleuetdefrance.fr |access-date=2009-11-05 |archive-date=8 March 2009 |archive-url=https://web.archive.org/web/20090308015835/http://www.bleuetdefrance.fr/ |url-status=dead }}</ref>
In France the {{lang|fr|[[bleuet de France]]}} is the symbol of the [[Armistice with Germany (Compiègne)|11 November 1918]] [[armistice]] and, as such, a common symbol for [[veterans]] (especially the now defunct [[poilus]] of [[World War I]]), similar to the [[Remembrance poppy|Remembrance poppies]] worn in the United Kingdom and in Canada.<ref>{{cite web |language=fr |website=Le Bleuet de France |trans-website=French cornflower |title=Porter le Bleuet de France |trans-title=Wearing French Cornflower |quote=Depuis sa création en 1920, le Bleuet de France est le symbole de la mémoire et de la solidarité des français envers les anciens combattants, les victimes de guerre, les veuves et les orphelins. Il se porte sur le côté gauche, côté du cœur, chaque 8 mai et 11 novembre. |trans-quote=Since its creation in 1920, the Bleuet de France has been the symbol of the memory and solidarity of the French towards veterans, war victims, widows and orphans. It is worn on the left side, side of the heart, every May 8 and November 11. |url=http://www.bleuetdefrance.fr/ |access-date=2023-06-11 |archive-date=2023-05-24 |archive-url=https://web.archive.org/web/20230524182208/https://www.bleuetdefrance.fr/ |url-status=live}}</ref>


The cornflower is also the symbol for [[motor neurone disease]] and [[amyotrophic lateral sclerosis]].<ref>{{cite web |url=http://www.als.ca/cornflower.aspx |title=The Cornflower - an ALS symbol |publisher=Als.ca |date=2004-05-31 |access-date=2009-11-05 |url-status=dead |archive-url=https://web.archive.org/web/20090726145618/http://www.als.ca/cornflower.aspx |archive-date=2009-07-26 }}</ref><!--Why is this?-->
The cornflower is also the symbol for [[motor neurone disease]] and [[amyotrophic lateral sclerosis]].<ref>{{cite web |url=http://www.als.ca/cornflower.aspx |title=The Cornflower - an ALS symbol |publisher=Als.ca |date=2004-05-31 |access-date=2009-11-05 |url-status=dead |archive-url=https://web.archive.org/web/20090726145618/http://www.als.ca/cornflower.aspx |archive-date=2009-07-26 }}</ref><!--Why is this?-->
Line 123: Line 116:
A blue cornflower was used by [[Corning Glass Works]] for the initial release of Corning Ware [[Pyroceram]] cookware. Its popularity in the United States, Canada, United Kingdom and Australia was so high that it became the symbol of Corning Glass Works.
A blue cornflower was used by [[Corning Glass Works]] for the initial release of Corning Ware [[Pyroceram]] cookware. Its popularity in the United States, Canada, United Kingdom and Australia was so high that it became the symbol of Corning Glass Works.


==In paintings==
=== In paintings ===
<gallery widths="200px" heights="200px">
<gallery widths="200px" heights="200px">
File:Vincent van Gogh - Wheat Field with Cornflowers.jpg|[[Vincent van Gogh]], ''Wheat Field with Cornflowers'', 1890.
File:Левитан Васильки.jpg|[[Isaac Levitan]], ''Cornflowers'', 1894.
File:Левитан Васильки.jpg|[[Isaac Levitan]], ''Cornflowers'', 1894.
File:Osipov-Cornflowers-7oci10bw.jpg|[[Sergei Osipov (artist)|Sergei Osipov]], ''[[Cornflowers (painting)|Cornflowers]]'', 1976.
File:Group portrait with cornflowers by Igor Grabar, 1914.jpg|[[Igor Grabar]], ''Group Portrait with Cornflowers'', 1914.
File:Group portrait with cornflowers by Igor Grabar, 1914.jpg|[[Igor Grabar]], ''Group Portrait with Cornflowers'', 1914.
File:Vincent van Gogh - Wheat Field with Cornflowers.jpg|[[Vincent van Gogh]], ''Wheat Field with Cornflowers'', 1890.
File:Osipov-Cornflowers-7oci10bw.jpg|[[Sergei Osipov (artist)|Sergei Osipov]], ''[[Cornflowers (painting)|Cornflowers]]'', 1976.
File:Stamps_Ukrainian_flowers.jpg|Ukrainian stamp set: "Ukrainian Flowers" (2000), with cornflowers on the right. Painting by Kateryna Shtanko.
</gallery>
</gallery>


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* [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Centaurea&SPECIES_XREF=cyanus&TAXON_NAME_XREF=&RANK= Flora Europaea: ''Centaurea cyanus'']
* [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Centaurea&SPECIES_XREF=cyanus&TAXON_NAME_XREF=&RANK= Flora Europaea: ''Centaurea cyanus'']
* [https://web.archive.org/web/20090221122324/http://www.ukbap.org.uk/UKPlans.aspx?ID=198 UK Biodiversity Action Plan: ''Centaurea cyanus'']
* [https://web.archive.org/web/20090221122324/http://www.ukbap.org.uk/UKPlans.aspx?ID=198 UK Biodiversity Action Plan: ''Centaurea cyanus'']
* [https://www.plantlife.org.uk/application/files/6615/4108/6864/Brief_sheet_-_Cornflower_Centaurea_briefing_sheet.pdf Briefing sheet on ''Centaurea cyanus''] ([https://web.archive.org/web/20150924074146/http://www.plantlife.org.uk/uploads/documents/Brief sheet - Cornflower Centaurea briefing sheet.pdf archive]) from Plantlife's [http://www.plantlife.org.uk/wild_plants/plant_species/cornflower Cornflower (''Centaurea cyanus'') page]
* [https://www.plantlife.org.uk/application/files/6615/4108/6864/Brief_sheet_-_Cornflower_Centaurea_briefing_sheet.pdf Briefing sheet on ''Centaurea cyanus''] ([https://web.archive.org/web/20150924074146/http://www.plantlife.org.uk/uploads/documents/Brief sheet - Cornflower Centaurea briefing sheet.pdf archive]) from Plantlife's [http://www.plantlife.org.uk/wild_plants/plant_species/cornflower Cornflower (''Centaurea cyanus'') page] {{Webarchive|url=https://web.archive.org/web/20170101193512/http://www.plantlife.org.uk/wild_plants/plant_species/cornflower |date=1 January 2017 }}


{{Taxonbar|from=Q156921}}
{{Taxonbar|from=Q156921}}


{{National symbols of Germany}}
{{Authority control}}
{{Authority control}}


[[Category:Blue flowers]]
[[Category:Centaurea|Cyanus]]
[[Category:Centaurea|Cyanus]]
[[Category:Flora of Estonia]]
[[Category:Flora of Estonia]]

Latest revision as of 23:05, 4 December 2024

"Cornflower" redirects here. Not to be confused with Cornflour. For other uses, see Cornflower (disambiguation).

Centaurea cyanus
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Centaurea
Species:
C. cyanus
Binomial name
Centaurea cyanus
Centaurea cyanus (introduced species) near Peshastin, Chelan County, Washington

Centaurea cyanus, commonly known as cornflower or bachelor's button,[note 1] is an annual flowering plant in the family Asteraceae native to Europe. In the past, it often grew as a weed in cornfields (in the broad sense of "corn", referring to grains, such as wheat, barley, rye, or oats), hence its name. It is now endangered in its native habitat by agricultural intensification, particularly by over-use of herbicides. However, Centaurea cyanus is now also naturalised in many other parts of the world, including North America and parts of Australia through introduction as an ornamental plant in gardens and as a seed contaminant in crop seeds.[3]

Description

[edit]
Flowering shoot of cornflower.
I. Disk-floret in vertical section

Centaurea cyanus is an annual plant growing to 20–100 centimetres (8–39 in) tall, with grey-green branched stems. The leaves are lanceolate and 3–10 cm (1–4 in) long.[4] The flowers are most commonly an intense blue colour and arranged in flowerheads (capitula) of 1.5–3 cm diameter, with a ring of a few large, spreading ray florets surrounding a central cluster of disc florets. The blue pigment is protocyanin, which in roses is red.[5] Fruits are approx. 3.5 mm long with 2–3 mm-long pappus bristles.[6] It flowers all summer.[7]

Genetics

[edit]

Centaurea cyanus is a diploid flower (2n = 24).[8] The genetic diversity within populations is high, although there could be a future decline in diversity due to population fragmentation and intensive agriculture.[9] In general, Centaurea cyanus is a self-incompatible species. However, selfing still occurs occasionally, but results in inbreeding depression.[10]

Distribution and habitat

[edit]

Centaurea cyanus is native to temperate Europe, but is widely naturalized outside its native range.

It has been present in Britain and Ireland as an archaeophyte (ancient introduction) since the Iron Age.[11] In the United Kingdom, it has declined from 264 sites to just 3 sites in the last 50 years.[12]

In reaction to this, the conservation charity Plantlife named it as one of 101 species it would actively work to bring 'back from the brink'.[13]

In the County Clare (VC H9) in Ireland, C. cyanus is recorded in arable fields as very rare and almost extinct,[14] while in northeast Ireland, it was abundant before the 1930s.[15]

Ecology

[edit]

Weed in arable crops

[edit]

Centaurea cyanus is considered a noxious weed in arable crops, especially cereals and rapeseed.[16] In winter wheat, one plant per m2 can cause a yield loss of up to 30 kg / ha.[17] Centaurea cyanus produces around 800 seed per plant, which are either shed shortly before the harvest of cereals, or they are threshed together with the cereal grains, contributing to the further spread of the species by the harvesting machinery and contaminated seed. The occurrence of Centaurea cyanus strongly decreased during the last decades due to improved seed cleaning, more intensive nitrogen fertilization and herbicide use. However, Centaurea cyanus has become more common in cropland due to an increase in crop rotations dominated by winter cereals and rapeseed and the use of more selective herbicides with a low effectiveness against Centaurea cyanus.[16] In addition, the emergence of resistance against the herbicide class of sulfonylureas has been reported recently.[18] Due to its strong roots, Centaurea cyanus is difficult to control mechanically in spring.[16]

Fodder for insects and birds

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A honey bee on a cornflower

The pollen of Centaurea cyanus is used by several different insect species. Insects of the orders Hymenoptera and Diptera are particularly attracted by the flower.[19] As Centaurea cyanus is a self-incompatible species, it needs external pollination. The nectar of Centaurea cyanus is very sweet with a sugar content of 34%. Due to its high sugar production of up to 0.2 mg sugar per day and flower, the species is highly appreciated by beekeepers.[20]

The seeds of Centaurea cyanus are one of the favourite foods of the European goldfinch.

Control of insect pests

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Centaurea cyanus was found to produce volatiles attracting Microplitis mediator,[21] which is a major parasitoid of the cabbage moth (Mamestra brassicae), which is the most important pest of cabbage (Brassica oleracea) in central Europe. Planting Centaurea cyanus in cabbage fields as a companion plant was thus suggested as an alternative to the widespread use of insecticides to control Mamestra brassicae. Field experiments showed that planting Centaurea cyanus in cabbage fields at a density of 1 plant / m2 can result in a significant increase in parasitation of Mamestra brassicae larvae, predation of Mamestra brassicae eggs (e.g. by carabid beetles or spiders) and ultimately cabbage yield.[22]

Cultivation

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Several cultivars of Centaurea cyanus with varying pastel colours, including pink and purple, have been selected for ornamental purposes. The species is also grown for the cut flower industry in Canada for use by florists. Doubled blue cultivars (such as 'Blue Boy' or 'Blue Diadem') are most commonly used for this purpose, but white, pink, lavender and black (actually a very dark maroon) cultivars are also used, albeit to a lesser extent. There are varieties with blue, white, purple, pink or even black petals.

Breeding goals

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As for all ornamental plants, important goals of Centaurea cyanus breeding include the induction of phenotypic variation (e.g. in flower coloration, size and shape, foliage characteristics or plant height), higher flower yield, resistance to pests and diseases as well as tolerance to abiotic stress (e.g., extreme temperatures, drought or salinity).[23]

Soil and climate requirements

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Centaurea cyanus requires full sun and neutral (pH 6.6–7.5) to mildly alkaline (pH 7.6–7.8), moist and well-drained soil. However, Centaurea cyanus is quite tolerant to drought once established.[24]

Sowing

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For summer-blooming plants, sowing should be executed in late spring. In moderate climates, however, it is also possible to sow Centaurea cyanus in early fall. In this case, plants will already start to flower in the following spring. Recommended spacing between plants is approx. 20 to 30 cm.[24] Centaurea cyanus can germinate from up to 10 cm depth, but the best result is obtained at 1 cm sowing depth.[25] Germination occurs quickly after sowing.

Fertilization and cultural practices

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High phosphorus fertilization in mid-summer will increase flower production. Mulching is recommended to prevent drying out of the soil and exposure of the root system to the sun.[24]

Pests and diseases

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In general, Centaurea cyanus is not very susceptible to pests and plant diseases. However, it may be affected by stem rot and stem rust if grown too tightly [24] or by powdery mildew.[26] Furthermore, aphids and leafhoppers can cause relevant damage to Centaurea cyanus.[24]

Seed harvesting

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Seeds are harvested either by hand or, in an agricultural setting, with a seed harvesting machine. On average there are 97,000 seeds in a pound of cornflower seeds.[27]

Hand collecting can be time-consuming and yields are rather low.

A seed harvesting machine is more efficient than collecting the seeds by hand, but it is costly. The main principle of such a machine is that it brushes the ripe seeds off the plant and creates a cross flow fan action that generates sufficient air velocity to hold and gather the seeds into the seed bunker.[28]

Pruning

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Deadheading will encourage the plant to produce more blooms. Cornflowers are often used for ornamental purposes and by cutting them, up to their third leaves, they will produce more blooms and grow a bigger stem.

Uses

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Culinary

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Raw cornflower petals used as a dessert decoration ingredient on strawberry ice cream

The flowers of Centaurea cyanus can be eaten raw, dried or cooked.[29] Dried petals are used in foods, including in spices. Their main purpose is to add colour to food. There are cheeses or oils that contain raw petals. Petals can also be added to salads, drinks, and desserts for garnishing purposes in raw or dried form.

Dried petals are also used in teas and other beverages. Blue cornflower petals are sometimes one of the ingredients in Lady Grey tea.[30]

Medicine

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Centaurea cyanus contains a wide range of pharmacologically active compounds, such as flavonoids, anthocyanins and aromatic acids.[31] Especially the flower head finds application in herbal medicine, but leaves and seeds are also used for pharmacological purposes, albeit to a lesser extent.

In particular, extracts from the flower heads have anti-inflammatory properties used in the treatment of minor ocular inflammations.[32] Antioxidant properties are high due to ascorbic acid and phenolic compounds.[33] Furthermore, extracts of the flower head and vegetative parts of the plant were shown to have gastroprotective effects due to their content of quercetin, apigenin and caffeic acid derivates.[34]

Pigment

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The blue color of Centaurea cyanus is due to protocyanin, an anthocyanin pigment that is also found in roses.[35] Different anthocyanins derived from Centaurea cyanus are used as natural additives in food products, such as yoghurts.

Phytoremediation

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Centaurea cyanus has been evaluated for phytoremediation of soils contaminated with lead. Inoculation of the contaminated soil with Glomus spp. (fungus) and Pseudomonas spp. (bacterium) would significantly enhance the biomass production and lead uptake of Centaurea cyanus.[36]

In culture

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Cornflower pictured in the coat of arms of Keila

In folklore, cornflowers were worn by young men in love;[clarification needed] if the flower faded too quickly, it was taken as a sign that the man's love was not returned.[37]: 126 

The blue cornflower was one of the national symbols of Germany.[38] This is partly due to the story that when Queen Louise of Prussia was fleeing Berlin and pursued by Napoleon's forces, she hid her children in a field of cornflowers and kept them quiet by weaving wreaths for them from the flowers. The flower thus became identified with Prussia, not least because it was the same color as the Prussian military uniform.[39] After the unification of Germany in 1871, it went on to become a symbol of the country as a whole. For this reason, in Austria the blue cornflower is a political symbol for pan-German and rightist ideas.[40][41] It was worn as a secret symbol identifying members of the then-illegal NSDAP in Austria in the 1930s.[42][43] Members of the Freedom Party wore it at the openings of the Austrian parliament since 2006.[44][45][46] After the last general election 2017 they replaced it with the edelweiss.[47]

It was also the favourite flower of Louise's son Kaiser Wilhelm I.[48] Because of its ties to royalty, authors such as Theodor Fontane have used it symbolically, often sarcastically, to comment on the social and political climate of the time.[citation needed]

The cornflower is also often seen as an inspiration for the German Romantic symbol of the Blue Flower.[citation needed]

Due to its traditional association with Germany, the cornflower has been made the official symbol of the annual German-American Steuben Parade.

Logo of the Conservative People's Party of Estonia

The blue cornflower has been the national flower of Estonia since 1969 and symbolizes daily bread to Estonians. It is also the symbol of the Estonian Conservative People's Party.

It is also the symbol of the Finnish National Coalition Party, and the Liberal People's Party of Sweden, where it has since the dawn of the 20th century been a symbol for social liberalism.[citation needed]

It is the official flower of the Swedish province of Östergötland and the school flower of Winchester College and also of Dulwich College, where it is said to have been the favourite flower of the founder, Edward Alleyn.

In France the bleuet de France is the symbol of the 11 November 1918 armistice and, as such, a common symbol for veterans (especially the now defunct poilus of World War I), similar to the Remembrance poppies worn in the United Kingdom and in Canada.[49]

The cornflower is also the symbol for motor neurone disease and amyotrophic lateral sclerosis.[50]

Cornflowers are sometimes worn by Old Harrovians, former pupils of the British Harrow School.

A blue cornflower was used by Corning Glass Works for the initial release of Corning Ware Pyroceram cookware. Its popularity in the United States, Canada, United Kingdom and Australia was so high that it became the symbol of Corning Glass Works.

In paintings

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See also

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Explanatory notes

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  1. ^ Other names include bluebottle, bluecap, blue blob, blue bonnet, cornbottle, boutonierre flower, hurtsickle, and gogglebuster.[1][2]

References

[edit]
  1. ^ Rosamond Richardson, 2017, Britain's Wildflowers. Pavilion.
  2. ^ Grigson, Geoffrey (1975). The Englishman's Flora. Frogmore: Paladin. p. 419. ISBN 0586082093.
  3. ^ [1]. Daylilies in Australia, May 17, 2021
  4. ^ Keil, David J.; Ochsmann, Jörg (5 November 2020). "Centaurea cyanus - FNA". Flora of North America. Retrieved 18 June 2024.
  5. ^ Shiono M, Matsugaki N, Takeda K (2005). "Structure of the blue cornflower pigment". Nature. 436 (7052): 791. doi:10.1038/436791a. PMID 16094358. S2CID 4312804.
  6. ^ Lauber, Konrad; Wagner, Gerhart (1996). Flora Helvetica (in German). Berne: Paul Haupt Verlag. p. 1152. ISBN 3-258-05405-3.
  7. ^ Rose, Francis (1981). The Wild Flower Key. Frederick Warne & Co. pp. 386–387. ISBN 0-7232-2419-6.
  8. ^ Martin E., Dinç M., Duran A. (2009). "Karyomorphological Study of Eight Centaurea L. Taxa (Asteraceae) from Turkey". Turkish Journal of Botany 33:97–104.
  9. ^ Le Corre V., Bellanger S., Guillemin J.-P., Darmency H. (2014). "Genetic diversity of the declining arable plant Centaurea cyanus: Population fragmentation within an agricultural landscape is not associated with enhanced spatial genetic structure". Weed Research 54:436–444.
  10. ^ Bellanger, Solène; Guillemin, Jean-Philippe; Touzeau, Solène; Darmency, Henri (2015). "Variation of inbreeding depression in Centaurea cyanus L., a self-incompatible species". Flora. 212: 24–29. Bibcode:2015FMDFE.212...24B. doi:10.1016/j.flora.2015.02.003.
  11. ^ "Online atlas of the British & Irish flora: Centaurea cyanus (Cornflower)". Biological Records Centre and Botanical Society of Britain and Ireland. Retrieved 22 May 2016.
  12. ^ "Action plan for Centaurea cyanus". Ukbap.org.uk. Archived from the original on 21 February 2009. Retrieved 5 November 2009.
  13. ^ "Plantlife website". Plantlife.org.uk. Archived from the original on 27 January 2010. Retrieved 5 November 2009.
  14. ^ Skeffington, M.S. (2015). "Cornflower (Centaurea cynanus L.) and Good-king-henry (Chenopodium bonus-henricus L.)". Irish Naturalists' Journal. 34: 27–31.
  15. ^ Hackney, P. (1992). Stewart & Corry's Flora of the North-east of Ireland (Third ed.). Institute of Irish Studies and The Queen's University of Belfast. ISBN 0-85389-446-9.
  16. ^ a b c Gehring, K.; Seemann, W.; Thyssen, S. "Leitunkräuter in Getreide". LfL Bayern. Bayerische Landesanstalt für Landwirtschaft. Retrieved 26 July 2020.
  17. ^ Pallutt, B.; Flatter, A. (1998). "Variability of weed competitiveness in cereals and consequences for the correctness of thresholds". Journal of Plant Diseases and Protection (Special Issue 16): 333–344.
  18. ^ Adamczewski, K.; Kierzek, R. (2010). "Cornflower (Centaurea cyanus L.) cross resistant on ALS inhibitors". Progress in Plant Protection. 50 (1): 285–290.
  19. ^ Carreck N., Williams I. (2002). "Food for insect pollinators on farmland: insect visits to flowers of annual seed mixtures". Journal of Insect Conservation 6:13–23.
  20. ^ Helmut Horn, Cord Lüllmann: Das große Honigbuch, Kosmos, Stuttgart, 3. Auflage, 2006, ISBN 3-440-10838-4, S. 31
  21. ^ Belz, Elodie; Kölliker, Mathias; Balmer, Oliver (2013). "Olfactory attractiveness of flowering plants to the parasitoid Microplitis mediator: potential implications for biological control" (PDF). BioControl. 58 (2): 163–173. Bibcode:2013BioCo..58..163B. doi:10.1007/s10526-012-9472-0. S2CID 17117503.
  22. ^ Balmer, Oliver; Géneau, Céline E.; Belz, Elodie; Weishaupt, Bettina; Förderer, Gerda; Moos, Sebastian; Ditner, Nadine; Juric, Ivan; Luka, Henryk (2014). "Wildflower companion plants increase pest parasitation and yield in cabbage fields: Experimental demonstration and call for caution". Biological Control. 76: 19–27. Bibcode:2014BiolC..76...19B. doi:10.1016/j.biocontrol.2014.04.008.
  23. ^ "Breeding and Seed Production of Ornamental Crops". Retrieved 22 November 2020.
  24. ^ a b c d e "How to Grow Cornflower". American Meadows. Retrieved 5 November 2020.
  25. ^ Hanf, Martin (1943). "Keimung von Unkrauterun unter verschiedenen Bedingungen im Boden". Landwirtschaftliche Jahrbücher. 93 (2): 169–259.
  26. ^ "Centaurea Cyanus [sic]: Best Practices for Growing the Cornflower". Best Plants. 8 March 2019. Retrieved 5 November 2020.
  27. ^ "Tall Blue Cornflower Seeds". www.ufseeds.com. 2021. Retrieved 21 February 2021.
  28. ^ "Methods of seed harvesting". www.dpi.nsw.gov.au. 2017. Retrieved 17 November 2020.
  29. ^ Rop O., Mlcek J., Jurikova T., Neugebauerová J., Vabkova J. (2012). "Edible Flowers-A New Promising Source of Mineral Elements in Human Nutrition". Molecules 17:6672–83.
  30. ^ "Discovery Collection Orangery of Lady Grey - 15 Pyramid Tea Bags".
  31. ^ Al-Snafi A. (2015). "The pharmacological importance of Centaurea cynus - A review". International Journal of Pharmacy Review and Research 5:379–384.
  32. ^ Garbacki N., Gloaguen V., Damas J., Bodart P., Tits M., Angenot L. (1999). "Anti-inflammatory and immunological effects of Centaurea cyanus flower-heads". Journal of ethnopharmacology 68:235–241.
  33. ^ Lockowandt L., Pinela J., Roriz C., Pereira C., Abreu R., Calhelha R., Alves M., Barros L., Bredol M., Ferreira I. (2019). "Chemical features and bioactivities of cornflower (Centaurea cyanus L.) capitula: The blue flowers and the unexplored non-edible part". Industrial Crops and Products 128:496–503.
  34. ^ Pirvu L., Dragomir C., Schiopu S., Mihul S. (2012). "Vegetal extracts with gastroprotective activity. Part. I. Extracts obtained from Centaurea cyanus L. raw material". Romanian Biotechnological Letters 17:7169-7176.
  35. ^ Shiono M., Matsugaki N., Takeda K. (2005). "Structure of the blue cornflower pigment". Nature 436:791–791.
  36. ^ Karimi, Akbar; Khodaverdiloo, Habib; Rasouli-Sadaghiani, Habib (2018). "Microbial-Enhanced Phytoremediation of Lead Contaminated Calcareous Soil by Centaurea cyanus L.". CLEAN - Soil, Air, Water. 46 (2). Bibcode:2018CSAW...4600665K. doi:10.1002/clen.201700665.
  37. ^ Howard, Michael (1987). Traditional Folk Remedies. Century.
  38. ^ Cleene, Marcel; Lejeune, Marie Claire (2002). Compendium of Symbolic and Ritual Plants in Europe: Herbs. Man & Culture. ISBN 9789077135044. The Cornflower was once the floral emblem of Germany (hence the German common name Kaiserblume).
  39. ^ Reid, Marilyn (2007). Mythical Flower Stories. Lulu.com. p. 40. ISBN 978-1-84753-521-4.
  40. ^ Whiteside, Andrew G. (1993). Pan-Germanism: Anti-Semitism in Mass-Style Politics. Vol. 3/2. de Gruyter. p. 691. {{cite book}}: |work= ignored (help)
  41. ^ Unowsky, Daniel L. (2005). The Pomp and Politics of Patriotism: Imperial Celebrations in Habsburg Austria, 1848–1916. Purdue University Press. p. 157. ISBN 9781557534002.
  42. ^ "RIS Dokument". www.ris.bka.gv.at (in German). Retrieved 24 March 2018.
  43. ^ Josie Le Blond (11 January 2019). "New far-right German party adopts former secret Nazi symbol". The Guardian.
  44. ^ "Anklänge an illegale NSDAPler". ORF.at. 30 October 2006.
  45. ^ "KPÖ". www.kpoe.at (in German). Archived from the original on 25 March 2018. Retrieved 24 March 2018.
  46. ^ "Wirbel um Nazi-Blume bei der FPÖ". 29 October 2013. Retrieved 24 March 2018.
  47. ^ "FPÖ-Mandatare tragen heute Edelweiß statt Kornblume". Retrieved 24 March 2018.
  48. ^ Coulter, Lynn (2009). Gardening with Heirloom Seeds: Tried-and-True Flowers, Fruits, and Vegetables for a New Generation. ReadHowYouWant.com, Limited. p. 165. ISBN 978-1-4587-2217-1.
  49. ^ "Porter le Bleuet de France" [Wearing French Cornflower]. Le Bleuet de France [French cornflower] (in French). Archived from the original on 24 May 2023. Retrieved 11 June 2023. Depuis sa création en 1920, le Bleuet de France est le symbole de la mémoire et de la solidarité des français envers les anciens combattants, les victimes de guerre, les veuves et les orphelins. Il se porte sur le côté gauche, côté du cœur, chaque 8 mai et 11 novembre. [Since its creation in 1920, the Bleuet de France has been the symbol of the memory and solidarity of the French towards veterans, war victims, widows and orphans. It is worn on the left side, side of the heart, every May 8 and November 11.]
  50. ^ "The Cornflower - an ALS symbol". Als.ca. 31 May 2004. Archived from the original on 26 July 2009. Retrieved 5 November 2009.
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