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'''''Iris giganticaerulea''''', the '''giant blue iris''', is a species of [[iris (plant)|iris]], in the subgenus ''[[Iris subg. Limniris|Limniris]]'', in the series ''[[Louisiana iris|Hexagonae]]''. It is a [[rhizomatous]] [[perennial plant|perennial]], from northern America. It has long bright green leaves, very tall stems, one or two musky fragrant flowers, in a range of blue shades, from pale blue, to lavender blue, to bright blue, to dark blue, and to violet blue. Rarely, there is a white form.
'''''Iris giganticaerulea''''', the '''giant blue iris''', is a species of [[iris (plant)|iris]], in the subgenus ''[[Iris subg. Limniris|Limniris]]'', in the series ''[[Louisiana iris|Hexagonae]]''. It is a [[rhizomatous]] [[perennial plant|perennial]], from northern America. It has long bright green leaves, very tall stems and one or two musky fragrant flowers in a range of blue shades (pale, bright, dark, lavender and violet) or rarely white.


==Description==
==Description==
''Iris giganticaerulea'' (like its common name the 'Giant blue iris') is the largest species of the Louisiana Irises.<ref name=fedus/><ref name=ClaireAustin/>
''Iris giganticaerulea'' (the giant blue iris) is the largest species of the Louisiana irises.<ref name=fedus/><ref name=ClaireAustin/>


It has very large green rhizomes, which are between 5 and 12 inches (13 – 30&nbsp;cm) long and 0.75 to 1.5 inches (2–4&nbsp;cm) thick.<ref name="signa"/><ref name=efloras/>
It has very large green rhizomes, which are between 5 and 12 inches (13 – 30&nbsp;cm) long and 0.75 to 1.5 inches (2–4&nbsp;cm) thick.<ref name="signa"/><ref name=efloras/>
They are shallow rooted, marked with the scars (of the previous seasons) leaves, with many branches, which can form a large clump/colony growing up to 6 x 3 feet (182 x 91&nbsp;cm).<ref name=efloras/><ref name=landscape/><ref name=fedus>{{cite web |title=Iris giganticaerulea |url=http://www.fs.fed.us/wildflowers/beauty/iris/louisiana/iris_giganticaerulea.shtml |publisher=fs.fed.us |access-date=27 November 2014}}</ref>
They are shallow rooted, marked with the scars (of the previous seasons) leaves, with many branches, which can form a large clump/colony growing up to 6 x 3 feet (182 x 91&nbsp;cm).<ref name=efloras/><ref name=landscape/><ref name=fedus>{{cite web |title=Iris giganticaerulea |url=http://www.fs.fed.us/wildflowers/beauty/iris/louisiana/iris_giganticaerulea.shtml |publisher=fs.fed.us |access-date=27 November 2014}}</ref>


It has rising from the base of the plant, 4–6 bright green leaves, ensiform (sword-shaped) and measuring between 20 – 30 inches (50–76&nbsp;cm) long and 1 1/2 inches (4&nbsp;cm) wide.<!-- also <ref name=fedus/><ref name=efloras/>--><ref name=landscape/><ref name=wildflower/><ref name=cassidy/>
Rising from the plant's base are four to six bright green leaves, ensiform (sword-shaped) and between 20 and 30 inches (50–76&nbsp;cm) long, 1.5 inches (4&nbsp;cm) wide.<!-- also <ref name=fedus/><ref name=efloras/>--><ref name=landscape/><ref name=wildflower/><ref name=cassidy/>


It has very tall stems, that can grow between to between 28 – 71 inches (70–180&nbsp;cm) tall.<ref name="signa"/><ref name=wildflower/><ref name=HomeLandscape/><!-- also <ref name=zyco/><ref name=ClaireAustin/><ref name=efloras/><ref name=pacific/><ref name=cassidy/>--> They have two or three branches,<ref name=efloras/> with one or two terminal flowers rising above the leaves.<ref name=fedus/><ref name=efloras/> There may be up to twelve flowers on the plant.<ref name=cassidy/>
It has very tall stems, that can grow between 28 and 71 inches (70–180&nbsp;cm) tall.<ref name="signa"/><ref name=wildflower/><ref name=HomeLandscape/><!-- also <ref name=zyco/><ref name=ClaireAustin/><ref name=efloras/><ref name=pacific/><ref name=cassidy/>--> They have two or three branches,<ref name=efloras/> with one or two terminal flowers rising above the leaves.<ref name=fedus/><ref name=efloras/> There may be up to twelve flowers on the plant.<ref name=cassidy/>


It blooms from early to mid spring, in the UK and America,<ref name=ClaireAustin/><ref name=efloras/> with [[musky]] flowers.<ref name=fedus/><ref name=landscape/>
It blooms from early to mid spring, in the UK and America,<ref name=ClaireAustin/><ref name=efloras/> with [[Musk|musky]] flowers.<ref name=fedus/><ref name=landscape/>


It comes in a range of blue shades,<ref name=ClaireAustin/> from pale blue,<ref name=fedus/><ref name="signa"/><ref name=efloras/><!-- also <ref name=pacific/>--> to lavender blue,<ref name=fedus/><ref name=ClaireAustin/><ref name=zyco/><!-- also <ref name=cassidy/>--> to bright blue,<ref name=landscape/><ref name=wildflower/><ref name=zyco/><!-- also <ref name=ClaireAustin/><ref name=cassidy/>--> to dark blue,<ref name="signa"/><ref name=HomeLandscape/><ref name=pacific/> and to violet blue.<ref name=fedus/><ref name="signa"/><ref name=landscape/><!-- also <ref name=efloras/><ref name=cassidy/>--> Occasionally there is a white form,<ref name=ClaireAustin/><ref name="signa"/><ref name=cassidy/><!-- also <ref name=HomeLandscape/><ref name=zyco/>--> or yellowish white.<ref name=fedus/>
It comes in a range of blue shades,<ref name=ClaireAustin/> from pale blue,<ref name=fedus/><ref name="signa"/><ref name=efloras/><!-- also <ref name=pacific/>--> to lavender blue,<ref name=fedus/><ref name=ClaireAustin/><ref name=zyco/><!-- also <ref name=cassidy/>--> to bright blue,<ref name=landscape/><ref name=wildflower/><ref name=zyco/><!-- also <ref name=ClaireAustin/><ref name=cassidy/>--> to dark blue,<ref name="signa"/><ref name=HomeLandscape/><ref name=pacific/> and to violet blue.<ref name=fedus/><ref name="signa"/><ref name=landscape/><!-- also <ref name=efloras/><ref name=cassidy/>--> Occasionally there is a white form,<ref name=ClaireAustin/><ref name="signa"/><ref name=cassidy/><!-- also <ref name=HomeLandscape/><ref name=zyco/>--> or yellowish white.<ref name=fedus/>


The flowers are generally 5 to 6 inches (13 to 15&nbsp;cm) across.<ref name="signa"/><ref name=landscape/><ref name=zyco/> They have six petals, three outer sepals (called the falls), which are flaring (1.75 inch or 4&nbsp;cm wide), arch downwards and have a white or yellow or faint orange signal patch or ridge.<ref name=fedus/><ref name="signa"/><ref name=wildflower/><!-- also <ref name=cassidy/><ref name=zyco/><ref name=pacific/>--> It also has three inner sepals (called the standards), which are slightly erect or upright and narrower than the falls.<ref name=fedus/><ref name=wildflower/><ref name=cassidy/>
The flowers are generally 5 to 6 inches (13 to 15&nbsp;cm) across.<ref name="signa"/><ref name=landscape/><ref name=zyco/> They have six petals, three outer sepals (called the falls), which are flaring (1.75 inch or 4&nbsp;cm wide), arch downward and have a white or yellow or faint orange signal patch or ridge.<ref name=fedus/><ref name="signa"/><ref name=wildflower/><!-- also <ref name=cassidy/><ref name=zyco/><ref name=pacific/>--> They also have three inner sepals (called the standards), which are slightly erect or upright and narrower than the falls.<ref name=fedus/><ref name=wildflower/><ref name=cassidy/>


It has a 4–5&nbsp;cm long [[perianth]] tube, blue-violet style 1.3–1.5 inch (3.5–4&nbsp;cm long) and two-lobed [[Stigma (botany)|stigma]]e.<ref name=efloras/>
It has a 4–5&nbsp;cm long [[perianth]] tube, blue-violet style 1.3–1.5 inch (3.5–4&nbsp;cm long) and two-lobed [[Stigma (botany)|stigma]]e.<ref name=efloras/>
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===Genetics===
===Genetics===
As most irises are [[diploid]], they have two sets of [[chromosomes]]. This fact can be used to identify hybrids and classification of groupings.<ref name=ClaireAustin>{{cite book | first= Claire | last=Austin | title= Irises: A Gardener's Encyclopedia | publisher= Timber Press, Incorporated | isbn = 978-0881927306 | year = 2005 | ol = OL8176432M }}}</ref>
As most irises are [[diploid]], they have two sets of [[chromosomes]]. This fact can be used to identify hybrids and classification of groupings.<ref name=ClaireAustin>{{cite book | first= Claire | last=Austin | title= Irises: A Gardener's Encyclopedia | publisher= Timber Press, Incorporated | isbn = 978-0881927306 | year = 2005 | ol = OL8176432M }}</ref>
It has a chromosome count of 2n=44.<ref name="signa"/><ref name=efloras>{{cite web |title=FNA Vol. 26 Page 394 |url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101702 |publisher= efloras.org |access-date=28 November 2014}}</ref><ref name=pacific>{{cite web| title=Iris summary |date=14 April 2014 |url=http://www.pacificbulbsociety.org/pbswiki/files/Iris/Iris_Summary.pdf |publisher=pacificbulbsociety.org | access-date=28 November 2014}}</ref> It has been counted several times 2n=44, [[Lowell Fitz Randolph|Randolph]] 1934 (ex Randolph & Mitra in Bulletin of the American Iris Society 140, in 1956) 2n=44 Riley 1942, 2n=42, R C Foster 1937 (as Iris hexagona var. giganticaerulea)<ref name=Riley/> and 2n=44, Randolph, 1966.<ref name=american>{{cite web |first=Terry |last=Laurin |title=(SPEC) Iris giganticaerulea Small |date=19 August 2014 |url=http://wiki.irises.org/bin/view/Spec/SpecGiganticaerulea |publisher=wiki.irises.org |access-date=28 November 2014}}</ref>
It has a chromosome count of 2n=44.<ref name="signa"/><ref name=efloras>{{cite web |title=FNA Vol. 26 Page 394 |url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242101702 |publisher= efloras.org |access-date=28 November 2014}}</ref><ref name=pacific>{{cite web| title=Iris summary |date=14 April 2014 |url=http://www.pacificbulbsociety.org/pbswiki/files/Iris/Iris_Summary.pdf |publisher=pacificbulbsociety.org | access-date=28 November 2014}}</ref> It has been counted several times 2n=44, [[Lowell Fitz Randolph|Randolph]] 1934 (ex Randolph & Mitra in Bulletin of the American Iris Society 140, in 1956) 2n=44 Riley 1942, 2n=42, R C Foster 1937 (as Iris hexagona var. giganticaerulea)<ref name=Riley/> and 2n=44, Randolph, 1966.<ref name=american>{{cite web |first=Terry |last=Laurin |title=(SPEC) Iris giganticaerulea Small |date=19 August 2014 |url=http://wiki.irises.org/bin/view/Spec/SpecGiganticaerulea |publisher=wiki.irises.org |access-date=28 November 2014}}</ref>


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It was first published and described by [[John Kunkel Small|Small]] (of the [[New York Botanical Garden]],<ref name=zyco>{{cite web |first=Tom W. |last=Dillard |title=FROM NEW ORLEANS TO NEW ZEALAND, History and Development of The Louisiana Irises |url=http://zydecoirises.com/Species/Species.htm |publisher=zydecoirises.com |access-date=28 November 2014}}</ref>) in '[[Addisonia (journal)|Addisonia]]' in 1929.<ref name=ipni>{{cite web |title=Iridaceae Iris giganticaerulea Small |url=http://www.ipni.org/ipni/idPlantNameSearch.do?id=130075-2 |publisher=ipni.org (International Plant Names Index) |access-date=27 November 2014}}</ref>
It was first published and described by [[John Kunkel Small|Small]] (of the [[New York Botanical Garden]],<ref name=zyco>{{cite web |first=Tom W. |last=Dillard |title=FROM NEW ORLEANS TO NEW ZEALAND, History and Development of The Louisiana Irises |url=http://zydecoirises.com/Species/Species.htm |publisher=zydecoirises.com |access-date=28 November 2014}}</ref>) in '[[Addisonia (journal)|Addisonia]]' in 1929.<ref name=ipni>{{cite web |title=Iridaceae Iris giganticaerulea Small |url=http://www.ipni.org/ipni/idPlantNameSearch.do?id=130075-2 |publisher=ipni.org (International Plant Names Index) |access-date=27 November 2014}}</ref>


In 1937, [[Michael Foster (physiologist)|Foster]] thought that it was a variety of ''[[Iris hexagona]]'' and renamed it 'Iris hexagona var. giganticaerulea'.<ref name=Riley>{{cite journal |first=Herbert Parkes |last=Riley |date=December 1938 |title=A Character Analysis of Colonies of Iris Fulva, Iris Hexagona Var. Giganticaerulea and Natural Hybrids |journal=American Journal of Botany |publisher=Botanical Society of America |volume=25 |issue=10 |pages=727–738 |doi=10.2307/2436599|jstor=2436599 }}</ref>
In 1937, [[Michael Foster (physiologist)|Foster]] thought that it was a variety of ''[[Iris hexagona]]'' and renamed it ''Iris hexagona'' var. ''giganticaerulea''.<ref name=Riley>{{cite journal |first=Herbert Parkes |last=Riley |date=December 1938 |title=A Character Analysis of Colonies of Iris Fulva, Iris Hexagona Var. Giganticaerulea and Natural Hybrids |journal=American Journal of Botany |publisher=Botanical Society of America |volume=25 |issue=10 |pages=727–738 |doi=10.2307/2436599|jstor=2436599 }}</ref>
In 1966, Randolph re-assessed it and classified it as a separate species.<ref name=american/>
In 1966, Randolph re-assessed it and classified it as a separate species.<ref name=american/><ref name="ReferenceA">Mary A.Hood {{Google books|RiverTime: Ecotravel on the World's Rivers|_vmOwmSh12YC| page=38}}</ref>


Between 1950 and 1990, a large and fractious argument was waged over the state flower of [[Louisiana]]. Eventually, in 1990 a compromise was reached,<ref>Mary A.Hood {{Google books|RiverTime: Ecotravel on the World's Rivers|_vmOwmSh12YC| page=38}}</ref> the [[Magnolia grandiflora|Southern magnolia]] would be the state flower and ''Iris giganticaerulea'' was declared as the official [[List of U.S. state flowers|state wildflower]] of [[Louisiana]] in 1990.<ref>{{cite web| title=Louisiana Laws: RS 49:154.1 |url=http://www.legis.state.la.us/lss/lss.asp?doc=103541 |access-date=28 November 2014}}</ref><ref>{{cite web |title=LOUISIANA LAGNIAPPE |year=2014 |url=http://www.sos.la.gov/HistoricalResources/AboutLouisiana/LouisianaFacts/Pages/LouisianaLagniappe.aspx |publisher=sos.la.gov |access-date=1 December 2014}}</ref>
Between 1950 and 1990, a large argument was waged over the state flower of [[Louisiana]]. Then a compromise was reached whereby the [[Magnolia grandiflora|Southern magnolia]] became the state flower and the giant blue iris the [[List of U.S. state flowers|state wildflower]].<ref>{{cite web| title=Louisiana Laws: RS 49:154.1 |url=http://www.legis.state.la.us/lss/lss.asp?doc=103541 |access-date=28 November 2014}}</ref><ref>{{cite web |title=LOUISIANA LAGNIAPPE |year=2014 |url=http://www.sos.la.gov/HistoricalResources/AboutLouisiana/LouisianaFacts/Pages/LouisianaLagniappe.aspx |publisher=sos.la.gov |access-date=1 December 2014}}</ref><ref name="ReferenceA"/>


It was verified by [[United States Department of Agriculture]] and the [[Agricultural Research Service]] on 4 April 2003, and then updated on 2 December 2004.<ref name=grin>{{GRIN | access-date=5 August 2015}}</ref>
It was verified by [[United States Department of Agriculture]] and the [[Agricultural Research Service]] on 4 April 2003, and then updated on 2 December 2004.<ref name=grin>{{GRIN | access-date=5 August 2015}}</ref>
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This constricted range is due to limited hardiness of the species.<ref name=zyco/>
This constricted range is due to limited hardiness of the species.<ref name=zyco/>


It grows in shallow freshwater, within roadside ditches, clearings within swamps (including cypress swamps,<ref name=zyco/>), wet meadows and marshes.<ref name=efloras/><ref name=HomeLandscape/><ref name=fedus/><!-- also <ref name="signa"/><ref name=landscape/><ref name=wildflower/>-->
It grows in shallow freshwater, within roadside ditches, clearings within swamps (including cypress swamps,<ref name=zyco/>), [[wet meadow]]s and marshes.<ref name=efloras/><ref name=HomeLandscape/><ref name=fedus/><!-- also <ref name="signa"/><ref name=landscape/><ref name=wildflower/>-->
It is tolerant of [[brackish water]].<ref name=fedus/><ref name="signa"/>
It is tolerant of [[brackish water]].<ref name=fedus/><ref name="signa"/>


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They need full sunlight or partial shade, moist, acidic soils (ph level of 6.5) with a high organic and high fertility content (or [[humus]] rich).<!-- also <ref name="signa"/>--><ref name=landscape/><ref name=Gill>{{cite web |first=Dan |last=Gill |first2=Allen |last2=Owings |title=Louisiana Iris |year=1969 |publisher=Louisiana State University |url=http://www.lsuagcenter.com/NR/rdonlyres/02E30CFB-734D-40A2-9010-67D23EBFB26A/38089/pub1969LAIrisFORWEB2.pdf |access-date=7 December 2014}}</ref><ref name=Nash>Helen Nash {{Google books|Complete Guide to Water Garden Plants|ssKzSCtgyZ8C|pages=187–191}}</ref>
They need full sunlight or partial shade, moist, acidic soils (ph level of 6.5) with a high organic and high fertility content (or [[humus]] rich).<!-- also <ref name="signa"/>--><ref name=landscape/><ref name=Gill>{{cite web |first=Dan |last=Gill |first2=Allen |last2=Owings |title=Louisiana Iris |year=1969 |publisher=Louisiana State University |url=http://www.lsuagcenter.com/NR/rdonlyres/02E30CFB-734D-40A2-9010-67D23EBFB26A/38089/pub1969LAIrisFORWEB2.pdf |access-date=7 December 2014}}</ref><ref name=Nash>Helen Nash {{Google books|Complete Guide to Water Garden Plants|ssKzSCtgyZ8C|pages=187–191}}</ref>


For best flowering, moisture is essential during late autumn, winter and spring times (between October to May), when the plant starts to grow new leaves.<!-- also <ref name=american/>--><ref name=southern>Neil G. Odenwald and James R. Turner {{Google books |Identification, Selection, and Use of Southern Plants: For Landscape Design|S__s1QADDJoC|page=316}}</ref> They can be given a light feed between autumn and spring, if needed.<ref name=Gill/><ref name=Nash/>
For best flowering, moisture is essential during late autumn, winter and spring times (between October and May), when the plant starts to grow new leaves.<!-- also <ref name=american/>--><ref name=southern>Neil G. Odenwald and James R. Turner {{Google books |Identification, Selection, and Use of Southern Plants: For Landscape Design|S__s1QADDJoC|page=316}}</ref> They can be given a light feed between autumn and spring, if needed.<ref name=Gill/><ref name=Nash/>


Propagation is best carried out by [[Division (horticulture)|division]] of the rhizomes.<!-- also <ref name=landscape/><ref name=Gill/><ref name=Nash/>--><ref name=southern/><ref name=Australia>Nick Romanowski {{Google books|Water Garden Plants & Animals: The Complete Guide for All Australia|gQsVgaxl-9kC|pages=43–44}}</ref><ref>{{cite web |first=Dan |last=Gill |title=Get It Growing: It's Time To Divide Louisiana Irises Get It Growing News |date=9 August 2006 |url=http://www.lsuagcenter.com/news_archive/2006/september/get_it_growing/Get+It+Growing+Its+Time+To+Divide+Louisiana+Irises.htm |publisher= lsuagcenter.com |access-date=8 December 2014}}</ref>
Propagation is best carried out by [[Division (horticulture)|division]] of the rhizomes.<!-- also <ref name=landscape/><ref name=Gill/><ref name=Nash/>--><ref name=southern/><ref name=Australia>Nick Romanowski {{Google books|Water Garden Plants & Animals: The Complete Guide for All Australia|gQsVgaxl-9kC|pages=43–44}}</ref><ref>{{cite web |first=Dan |last=Gill |title=Get It Growing: It's Time To Divide Louisiana Irises Get It Growing News |date=9 August 2006 |url=http://www.lsuagcenter.com/news_archive/2006/september/get_it_growing/Get+It+Growing+Its+Time+To+Divide+Louisiana+Irises.htm |publisher=lsuagcenter.com |access-date=8 December 2014 |archive-date=13 December 2014 |archive-url=https://web.archive.org/web/20141213204235/http://www.lsuagcenter.com/news_archive/2006/september/get_it_growing/Get+It+Growing+Its+Time+To+Divide+Louisiana+Irises.htm |url-status=dead }}</ref>
Which is best carried out in early autumn or early spring, when the plants are dormant. The ground must be prepared pre-planting, with the addition of a generous amount of organic matter and the soils dug to about 6 inches deep (to allow for new root growth). Plants require dividing every 3–4 years to promote good flowering. They can combine with other plants but tend to 'move' to suitable positions.<ref name=landscape/><ref name=Gill/><ref name=Nash/><!-- also <ref name=southern/>-->
Which is best carried out in early autumn or early spring, when the plants are dormant. The ground must be prepared pre-planting, with the addition of a generous amount of organic matter and the soils dug to about 6 inches deep (to allow for new root growth). Plants require dividing every 3–4 years to promote good flowering. They can combine with other plants but tend to 'move' to suitable positions.<ref name=landscape/><ref name=Gill/><ref name=Nash/><!-- also <ref name=southern/>-->


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New plantings need to be mulched to prevent sun-scalding.<ref name=Gill/><ref name=Nash/> It is also recommended to be added to during winter.<ref name=landscape/>
New plantings need to be mulched to prevent sun-scalding.<ref name=Gill/><ref name=Nash/> It is also recommended to be added to during winter.<ref name=landscape/>


The iris seed is not hard to raise but a very slow process.<ref name=Australia/> It can take many months to germinate (between 3–12 months) with a 50% germination average.<ref name=Nash/> They then can take 3–5 years before reaching flowering stage.<ref name=Australia/>
The iris seed is not hard to raise but a very slow process.<ref name=Australia/> It can take many months to germinate (between 3 and 12 months) with a 50% germination average.<ref name=Nash/> They then can take 3–5 years before reaching flowering stage.<ref name=Australia/>


Seeds should be harvested from the plant after flowering but they must be from mature seed pods. They then should be stored in paper bags, as seed stored in glass containers often goes mouldy.<ref name=Nash/>
Seeds should be harvested from the plant after flowering but they must be from mature seed pods. They then should be stored in paper bags, as seed stored in glass containers often goes mouldy.<ref name=Nash/>
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==Sources==
==Sources==
* British Iris Society, A Guide to Species Irises: Their Identification and Cultivation (1997)
* British Iris Society, A Guide to Species Irises: Their Identification and Cultivation (1997)

==External links==
==External links==
*[https://www.flickr.com/photos/chobe_birds/14247015796/ Flickr images of iris giganticaerulea]
*[https://www.flickr.com/photos/chobe_birds/14247015796/ Flickr images of iris giganticaerulea]
*[http://www.southeasternflora.com/view_flora.asp?plantid=1533 Images of the iris]
*[http://www.southeasternflora.com/view_flora.asp?plantid=1533 Images of the iris]



{{Commons category-inline|Iris giganticaerulea}}
{{Commons category-inline|Iris giganticaerulea}}

Latest revision as of 21:35, 9 May 2023

Iris giganticaerulea
Wild blue iris blooming in swamp at Barataria Preserve, Louisiana

Vulnerable  (NatureServe)
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Iridaceae
Genus: Iris
Subgenus: Iris subg. Limniris
Section: Iris sect. Limniris
Series: Iris ser. Hexagonae
Species:
I. giganticaerulea
Binomial name
Iris giganticaerulea
Synonyms[1]
  • Iris aurilinea Alexander
  • Iris citricristata Small
  • Iris elephantina Small
  • Iris fluviatilis Small
  • Iris hexagona var. giganticaerulea (Small) R.C.Foster
  • Iris miraculosa Small
  • Iris venulosa Alexander
  • Iris wherryana Small
  • Limniris giganticaerulea (Small) Rodion.

Iris giganticaerulea, the giant blue iris, is a species of iris, in the subgenus Limniris, in the series Hexagonae. It is a rhizomatous perennial, from northern America. It has long bright green leaves, very tall stems and one or two musky fragrant flowers in a range of blue shades (pale, bright, dark, lavender and violet) or rarely white.

Description[edit]

Iris giganticaerulea (the giant blue iris) is the largest species of the Louisiana irises.[2][3]

It has very large green rhizomes, which are between 5 and 12 inches (13 – 30 cm) long and 0.75 to 1.5 inches (2–4 cm) thick.[4][5] They are shallow rooted, marked with the scars (of the previous seasons) leaves, with many branches, which can form a large clump/colony growing up to 6 x 3 feet (182 x 91 cm).[5][6][2]

Rising from the plant's base are four to six bright green leaves, ensiform (sword-shaped) and between 20 and 30 inches (50–76 cm) long, 1.5 inches (4 cm) wide.[6][7][8]

It has very tall stems, that can grow between 28 and 71 inches (70–180 cm) tall.[4][7][9] They have two or three branches,[5] with one or two terminal flowers rising above the leaves.[2][5] There may be up to twelve flowers on the plant.[8]

It blooms from early to mid spring, in the UK and America,[3][5] with musky flowers.[2][6]

It comes in a range of blue shades,[3] from pale blue,[2][4][5] to lavender blue,[2][3][10] to bright blue,[6][7][10] to dark blue,[4][9][11] and to violet blue.[2][4][6] Occasionally there is a white form,[3][4][8] or yellowish white.[2]

The flowers are generally 5 to 6 inches (13 to 15 cm) across.[4][6][10] They have six petals, three outer sepals (called the falls), which are flaring (1.75 inch or 4 cm wide), arch downward and have a white or yellow or faint orange signal patch or ridge.[2][4][7] They also have three inner sepals (called the standards), which are slightly erect or upright and narrower than the falls.[2][7][8]

It has a 4–5 cm long perianth tube, blue-violet style 1.3–1.5 inch (3.5–4 cm long) and two-lobed stigmae.[5]

After flowering, it has bright green ellipsoid capsules 3–4 inches (7–10 cm) long by 1 inch (3 cm) wide, which are hexagonal in cross section and shaped like a D.[5][12]

Genetics[edit]

As most irises are diploid, they have two sets of chromosomes. This fact can be used to identify hybrids and classification of groupings.[3] It has a chromosome count of 2n=44.[4][5][11] It has been counted several times 2n=44, Randolph 1934 (ex Randolph & Mitra in Bulletin of the American Iris Society 140, in 1956) 2n=44 Riley 1942, 2n=42, R C Foster 1937 (as Iris hexagona var. giganticaerulea)[13] and 2n=44, Randolph, 1966.[12]

Taxonomy[edit]

It has the common name of Giant blue iris,[7][14][15] or Giant blue flag.[4][6][9] Note, the blue flag is normally Iris virginica.

It was first published and described by Small (of the New York Botanical Garden,[10]) in 'Addisonia' in 1929.[16]

In 1937, Foster thought that it was a variety of Iris hexagona and renamed it Iris hexagona var. giganticaerulea.[13] In 1966, Randolph re-assessed it and classified it as a separate species.[12][17]

Between 1950 and 1990, a large argument was waged over the state flower of Louisiana. Then a compromise was reached whereby the Southern magnolia became the state flower and the giant blue iris the state wildflower.[18][19][17]

It was verified by United States Department of Agriculture and the Agricultural Research Service on 4 April 2003, and then updated on 2 December 2004.[20]

Distribution and habitat[edit]

It is native to northern America.[20]

Range[edit]

Iris giganticaerulea is native to Alabama, Louisiana,[2][3][4] (on the west edge of Mississippi River), eastern Texas,[2][6][10] and Mississippi in the United States.[5][11]

This constricted range is due to limited hardiness of the species.[10]

It grows in shallow freshwater, within roadside ditches, clearings within swamps (including cypress swamps,[10]), wet meadows and marshes.[5][9][2] It is tolerant of brackish water.[2][4]

Cultivation[edit]

Giant Blue Iris Seeds

The Louisiana irises generally all have similar cultivation requirements, with minor differences. They need full sunlight or partial shade, moist, acidic soils (ph level of 6.5) with a high organic and high fertility content (or humus rich).[6][21][22]

For best flowering, moisture is essential during late autumn, winter and spring times (between October and May), when the plant starts to grow new leaves.[23] They can be given a light feed between autumn and spring, if needed.[21][22]

Propagation is best carried out by division of the rhizomes.[23][24][25] Which is best carried out in early autumn or early spring, when the plants are dormant. The ground must be prepared pre-planting, with the addition of a generous amount of organic matter and the soils dug to about 6 inches deep (to allow for new root growth). Plants require dividing every 3–4 years to promote good flowering. They can combine with other plants but tend to 'move' to suitable positions.[6][21][22]

If using a fertilizer, sprinkle around the plant in late January or February, before the plant is in flower.[21][22][23]

New plantings need to be mulched to prevent sun-scalding.[21][22] It is also recommended to be added to during winter.[6]

The iris seed is not hard to raise but a very slow process.[24] It can take many months to germinate (between 3 and 12 months) with a 50% germination average.[22] They then can take 3–5 years before reaching flowering stage.[24]

Seeds should be harvested from the plant after flowering but they must be from mature seed pods. They then should be stored in paper bags, as seed stored in glass containers often goes mouldy.[22]

Iris giganticaerulea and Iris hexagona are considered too tender for cultivation in the UK.[8][26] Since it needs moist acid soils, with warm summers and milder winters.[26]

It is hardy to USDA Zone 7 to 11 (or 5 and 6 if protected during the winter).[4][6]

It is often available at water garden centres.[4]

Hybrids[edit]

Iris giganticaerulea can easily hybridize with other Louisiana irises to create new variants.

Several American garden nurseries and plant breeders have created many Iris giganticaerulea cultivars including, 'Angel Wings', 'Atrocyanea', 'Barbara Elaine Taylor', 'Bayou Barataria', 'Bayou Boeuf', 'Bayou St John', 'Bette Lee', 'Billy Mac', 'Biloxi', 'Cameron White', 'China Blue', 'Citricristata', 'Citricristata Alba', 'Citriviola', 'Coteau Holmes', 'Creole Can-Can', 'Easter Surprise', 'Elephantina', 'Excitement', 'Florence Zacharie', 'Gentilly Road', 'Gheen's White', 'Giganticaerulea Alba', 'Giganticaerulea Royal', 'Gulf Mist', 'Her Highness', 'High Hat', 'Iberville', 'Isle Bonne', 'Joe Mac', 'Kildea', 'La Bahia ', 'Lafitte', 'La Premiere', 'Laughing Water', 'Lazy Day', 'Longfellow's Gabriel', 'Mandeville', 'Miraculosa', 'Paludicola', 'Ruth Holleyman', 'Silverblu ', 'Snow Flag', 'Snow Goose', 'Southern Accent','Spanish Fort', 'Trixie'.[12]

Other crosses include with Iris fulva to produce 'Iris × vinicolor' Small.[5]

References[edit]

  1. ^ "Iris giganticaerulea Small is an accepted name". theplantlist.org. 23 March 2013. Retrieved 27 November 2014.
  2. ^ a b c d e f g h i j k l m n "Iris giganticaerulea". fs.fed.us. Retrieved 27 November 2014.
  3. ^ a b c d e f g Austin, Claire (2005). Irises: A Gardener's Encyclopedia. Timber Press, Incorporated. ISBN 978-0881927306. OL 8176432M.
  4. ^ a b c d e f g h i j k l m n Kramb, D. (20 September 2004). "Iris giganticaerulea". signa.org (Species Iris Group of North America). Retrieved 5 December 2014.
  5. ^ a b c d e f g h i j k l "FNA Vol. 26 Page 394". efloras.org. Retrieved 28 November 2014.
  6. ^ a b c d e f g h i j k l "Iris". rslandscapedesign.blogspot.co.uk. 13 February 2010. Retrieved 10 December 2014.
  7. ^ a b c d e f "Iris giganticaerulea". wildflower.org. Retrieved 28 November 2014.
  8. ^ a b c d e Cassidy, George E.; Linnegar, Sidney (1987). Growing Irises (Revised ed.). Bromley: Christopher Helm. p. 146. ISBN 978-0-88192-089-5.
  9. ^ a b c d Brzuszek, Robert F. (21 August 2014). "Louisiana Iris in the Home Landscape". msucares.com. Retrieved 27 November 2014.
  10. ^ a b c d e f g Dillard, Tom W. "FROM NEW ORLEANS TO NEW ZEALAND, History and Development of The Louisiana Irises". zydecoirises.com. Retrieved 28 November 2014.
  11. ^ a b c "Iris summary" (PDF). pacificbulbsociety.org. 14 April 2014. Retrieved 28 November 2014.
  12. ^ a b c d Laurin, Terry (19 August 2014). "(SPEC) Iris giganticaerulea Small". wiki.irises.org. Retrieved 28 November 2014.
  13. ^ a b Riley, Herbert Parkes (December 1938). "A Character Analysis of Colonies of Iris Fulva, Iris Hexagona Var. Giganticaerulea and Natural Hybrids". American Journal of Botany. 25 (10). Botanical Society of America: 727–738. doi:10.2307/2436599. JSTOR 2436599.
  14. ^ "Iris giganticaerulea". facstaff.hsc.unt.edu. Retrieved 28 November 2014.
  15. ^ "PLANT CHECKLIST". americaswetlandresources.com. Retrieved 10 December 2014.
  16. ^ "Iridaceae Iris giganticaerulea Small". ipni.org (International Plant Names Index). Retrieved 27 November 2014.
  17. ^ a b Mary A.Hood Ecotravel on the World's Rivers&pg=PA38 _vmOwmSh12YC, p. 38, at Google Books
  18. ^ "Louisiana Laws: RS 49:154.1". Retrieved 28 November 2014.
  19. ^ "LOUISIANA LAGNIAPPE". sos.la.gov. 2014. Retrieved 1 December 2014.
  20. ^ a b "Iris giganticaerulea". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 5 August 2015.
  21. ^ a b c d e Gill, Dan; Owings, Allen (1969). "Louisiana Iris" (PDF). Louisiana State University. Retrieved 7 December 2014.
  22. ^ a b c d e f g Helen Nash Guide to Water Garden Plants ssKzSCtgyZ8C at Google Books
  23. ^ a b c Neil G. Odenwald and James R. Turner Selection, and Use of Southern Plants: For Landscape Design&pg=PA316 S__s1QADDJoC, p. 316, at Google Books
  24. ^ a b c Nick Romanowski Garden Plants & Animals: The Complete Guide for All Australia gQsVgaxl-9kC at Google Books
  25. ^ Gill, Dan (9 August 2006). "Get It Growing: It's Time To Divide Louisiana Irises Get It Growing News". lsuagcenter.com. Archived from the original on 13 December 2014. Retrieved 8 December 2014.
  26. ^ a b Stebbings, Geoff (1997). The Gardener's Guide to Growing Irises. Newton Abbot: David and Charles. p. 18. ISBN 978-0715305393.

Sources[edit]

  • British Iris Society, A Guide to Species Irises: Their Identification and Cultivation (1997)

External links[edit]

Media related to Iris giganticaerulea at Wikimedia Commons Data related to Iris giganticaerulea at Wikispecies

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