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Iris setosa
Species of flowering plant From Wikipedia, the free encyclopedia
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Iris setosa, known as the beachhead iris, bristle-pointed iris, or a number of other common names, is a species of flowering plant in the genus Iris of the family Iridaceae. It belongs the subgenus Limniris and the series Tripetalae. It is a rhizomatous perennial found in a wide range across and below the Arctic circle, including in Alaska, Maine, Canada (including British Columbia, Newfoundland, Quebec and Yukon), Russia (including Siberia), China, Korea, and Japan. The plant has tall branching stems, mid green leaves and violet, purple-blue, violet-blue, blue, or lavender flowers, or, rarely, pink or white flowers.
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Description
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Iris setosa is similar in form to a miniature Japanese iris,[2] or a shorter-lived dwarf version of Iris sibirica.[3]
The shallowly rooted, large, branching rhizomes spread over time to create large clumps.[4][5][6] The rhizomes are grey-brown, thick, and covered with old maroon-brown fibrous material, the remains of the previous season's leaves.[7][8][9]
I. setosa has branched stems that are very variable in height,[10] ranging from 10 cm (5 inches) to 1 m (3 ft) tall.[6][3][4] The larger plants can grow beyond the height of the leaves.[2][8][11] The roundish stems are 1.5–9 cm (0.6–4 in) in diameter with 1 to 3 branches.[7][8]
Iris setosa has grass-like,[12] lanceolate (sword-shaped),[6][13] medium-green leaves[3][5][6] with a purple-tinged base.[5][8][9] Its leaves can measure 30–60 cm (12–24 in) long by 0.8–2.5 cm (0.3–1 in) wide.[5][6][13]
The plant bears 3–4 flowers per stem (for a total of 6 and 13 on the whole plant)[3][10] in groups of 3.[11][12]
It blooms between June and July.[14][15][16]
The large flowers measure 5–8 cm (3–6 in) across,[7][9][10] usually 7–8 cm (2.8–3.1 in).[7][11] Depending on their location,[4] they come in a range of shades of blue and purple including violet,[11][17] purple-blue,[2][4][13] violet-blue,[10][18] blue,[11][10][12] and lavender.[13] Very occasionally, there are pink or white forms.[11][17]
Like other irises, the plant has two sets of three petals: three large sepals (outer petals), known as the "falls," and three smaller inner petals (or tepals), known as the "standards."[19] The sepals can be deeply veined dark purple with a yellow-white center, known as the "signal."[11][12] The standards are so small that they are reduced almost to bristles,[4][10] which gives the flower a flat, three-petaled appearance.[2][11]
The perianth tube (floral tube) is about 1 cm (0.4 in) long,[7][8] normally dark blue-violet to red-purple with darker veins.[8]
The plant is self-fertile,[16] being hermaphrodite (having both male and female organs), and is pollinated by insects.[16] The stamens are about 2 cm (0.8 in) long with purple anthers and the ovary about 1 cm (0.4 in) long.[8]
After the flowers have finished blooming, the seeds ripen between August and September.[7][16] They are cased within a green seed capsule (measuring 2.5 cm by 1.25 cm), which is loculicidal,[6][8] or cylindrical,[4][7] and turns pale brown when it ripens.[4][9] It has 6 ribs along its sides.[7]
The pale brown to dark red seeds,[7][8] about 2–3 mm in size,[8] have a distinct raised raphe (tissue ridge) along the length of one edge.[9][17]
Biochemistry
In 2012, a genetic study was carried out on Iris laevigata and several closely related species, including Iris ensata, Iris setosa, Iris halophila, Iris scariosa, Iris potaninii, Iris tenuifolia, Iris bloudowii, and Iris sanguinea.[20] Flavonoids also have been analysed from the flowers and leaves of the Iris japonica,[21] Iris pseudacorus,[22] Iris gracilipes[23] and Iris setosa.[24][25]
Most irises are diploid, having two sets of chromosomes, and this can be used to identify hybrids and classify groupings.[19] Most Iris setosa specimens have a chromosome count of 2n=38,[17][26][27] found by Simonet in 1934.[7][8][28] However, specimens from Primorskii Krai in Russia were found to have a chromosome count of 2n=28.[29]
Chromosome research has found that a progenitor of Iris setosa and a progenitor of Iris virginica were the parents of Iris versicolor.[26]
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Nomenclature and taxonomy
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The name "setosa" is derived from the Latin word seta, meaning "bristle" or "hairy,"[6] referring to the true petals ("standards") of the flower, which compared to those of other Iris species are small almost to the point of being absent.[30][31]
Iris setosa has several common names, including "beachhead iris," (because it is tolerant of salt air or maritime conditions and sometimes encountered in rocky ground above shorelines,) especially in Canada;[18][26][32] "wild flag iris;"[33][34] "Alaska iris;" [13][31][35] "Arctic Iris," or "dwarf Arctic iris," because it grows into the Arctic Circle (and thus its scientific name was once Iris arctica);[36][37] "Arctic blue flag;"[18][26][31] and in the UK, "bristle-pointed iris."[10][38][39]
In Japan, it is known as hiougi-ayame (檜扇菖蒲/ヒオウギアヤメ).[27] In China, it is called "shan yuan wei" (山鸢尾).[7]
It is occasionally confused with Iris hookeri,[40] perhaps because several synonyms of Iris hookeri are I. setosa variants (I. setosa var. canadensis Foster, I. setosa f. pallidiflora Fernald, I. setosa subsp. pygmaea C.E.Lundstr. and I. setosa f. zonalis Eames).[41]
It was first published by Link (based on an earlier description by Pallas) in Jahrbücher der Gewächskunde, translated as "Yearbook of Greenhouse," (Berlin and Leipzig) in 1820.[42] It was originally described from specimens found in east Siberia.[8][9] It was then published in William Rickatson Dykes (Iris 1913 p. 92) as Iris brachycuspis, which was later regarded as a synonym.[1] In 1824, it was also published as Iris brachycuspsi by Fisch. ex Sims in the Botanical Magazine, which is also now regarded as a synonym.[9]
Iris setosa is an accepted name by the RHS, and gained the Royal Horticultural Society's Award of Garden Merit (RHS AGM).[38][43]
It is one of the three iris species in the Iris flower data set outlined by Ronald Fisher in his 1936 paper "The use of multiple measurements in taxonomic problems" as an example of linear discriminant analysis.[44]
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Distribution and habitat
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Range
The only iris species that is native to both Asia and North America,[4][15] Iris setosa has a circum-arctic distribution.
In the U.S., it ranges northward to the Brooks Range and southward to South-Central Alaska and the coastal Aleutian islands in Alaska,[18][14] and is also found in Maine.[18] In Canada, its range includes British Columbia, Newfoundland, Quebec,[18] and the Yukon Territory.
In Russia, its range includes near the lower Lena River in Siberia. In China, its range includes Manchuria and east Jilin. In Japan, its range includes Hokkaido and extends southward to Honshu.[27] It is also found in Korea.[25][30][26]
The form of I. setosa that grows in Canada is thought to be slightly different from the Asian form.[4] In Canada, it is found as far south as the shores of the Gulf of St. Lawrence and as far north as the estuary of Saint-Vallier, in Bellechasse county, Quebec.[4]
I. setosa is found in many of Alaska's national parks, including Glacier Bay, Kobuk Valley, Lake Clark, Wrangell–St. Elias, Katmai, and Kenai Fjords, as well as Acadia in Maine, although its range is not limited to inside national parks.[45] In Alaska, it is not found north of the Brooks Range.
In Japan, it is present in large numbers in Akkeshi, in eastern Hokkaido, Japan.[46]
Habitat
Iris setosa is normally considered a wetland plant, but it grows well in dry soil, too.[14] It is tolerant of many kinds of habitats, and as such can be found in meadows, bogs and swamps; beside rivers, streams, and lakes[14] (especially on rocky shores);[18] in beaches and on dunes and headlands;[4] and in light woodland.[19][27][18] It can grow in gravelly soils and even sand.[4] Though it is normally found at 1,500–2,500 m (4,900–8,200 ft) above sea level,[7][15]
Conservation
In 2014, two variants of I. setosa, vars. hondoensis and nasuensis, were listed as crtically threatened in Japan.[47]
Cultivation
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Iris setosa can adapt to various conditions, except heavy clay soils that dry out in summer.[19][31] It prefers to grow in moist or wet soils[2][6][18][16] and can tolerate bog conditions,[17][31] especially during the growing season, when it needs a lot of moisture,[11][17] and dislikes soils containing lime.[2][3][31] It prefers to grow in partial shade, as full sun risks drought conditions.[31][36][3]
It is also suited to sunny portions of woodland gardens or bog gardens.[16] Iris setosa is suitable to be grown in the front of a border.[clarification needed] Miniature versions are also suitable for rock gardens or sinks.[2]
Similar to other rhizomatous irises, the rhizome should be planted with the top of the rhizome uncovered with soil. If covered or planted too deep, it risks rotting.[36]
In mild temperate areas, the leaves are evergreen and can survive the winter. However, if the leaves are trimmed before the winter to reduce wind rockage and root disturbance, new leaves will emerge in spring.[36]
Some authors[who?] have suggested that irises are deer-proof. This is thought[by whom?] to be incorrect - the case may be that the leaves simply grow back when eaten by deer.[31]
Aphids Macrosiphum euphorbiae and Myzus ornathus can be found on the plant.[48]
Hardiness
Iris setosa is one of the hardiest species of irises,[11] but does not grow as well in warm climates due to its need a cold dormant period in winter.[17] As a native plant of Alaska, it is extremely cold-hardy (−30 °F (−34 °C) would not kill it).[31] It would only be killed if never given any summer at all.[36]
It is hardy to USDA Zone 3–7,[18] 3–8,[6] or 4–8,[16] but may tolerate Zone 2 and Zone 9 in perfect conditions.[17][36]
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Propagation
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Iris setosa can be propagated by seed or by division.
As with all irises, it can be difficult to propagate from seed (in the US). It is easier to do so by rhizome divisions[4] as the plant propagates naturally by rhizomes.[14] Division is best undertaken in spring and autumn if possible, ideally in September,[11] (about 4–6 weeks after flowering).[16][36] It can be done annually, but it is better to do so every third year, or whenever the plant has spread enough thatits center no longer produces any flowering stems.[31] If the plant is only divided into thirds or quarters, the new divisions can be planted straight away, but if it is divided into very small sections (for maximum number of plants), these should be put in a cold frame until the following spring, by which time they should have grown new roots.[16][31]
It is easier to grow from seed in the UK[3][clarification needed] because the seed requires a cold period (freeze/thaw period).[11][14] Seeds of the iris can be shaken from the seed capsule in mid-August.[14] They should be planted into beds or trays in a cold frame, sown into drills 1/4 to 1/2 inch deep.[14] If not sown straight away, they should be frozen for storage. In spring, the seedlings should be 'pricked out' into individual pots when they are large enough to handle. They can then be grown in the greenhouse or cold frame for their first year and planted out into their permanent positions in late spring or early summer.[14] New plants should be planted in September.[2] It takes at least two years to grow a plant from seed to flowering plant.[14]
Hybrids and cultivars
In the wild, Iris setosa forms hybrids with I. versicolor, the larger blue flag iris. Specimens of such hybrids have been observed on Anticosti Island, Quebec.[4] Iris setosa also hybridizes very easily with other Iris species, including Siberian and Californian irises,[19] and is therefore often used by breeders of iris hybrids.[11]
Many variants are known around the world, including three in Japan, each only found in limited areas of Honshu island.[15]
Japanese variants
Iris setosa var. hondoensis was found in Hondo, Japan, in 1930.[15] It has large purple flowers and is low-branching, robust, and approximately 80 cm (31 in) high. It is assumed[by whom?] to be a hybrid with Iris laevigata.[49] It has chromosome numbers of 2n=54,[15] but may be triploid.[8]
Iris setosa var. nasuensis, found near the city of Nasu, grows up to 1 m (39 in) tall. It has broader leaves than other varieties of Iris setosa and large flowers (similar to 'Iris laevigata'), but small bracts.[11][15] Like var. hondoensis, it has chromosome numbers of 2n=54,[15] but may be triploid.[8]
Iris 'Shiga Ayame' is a hybrid of Iris setosa and Iris sanguinea. It was found in the Shiga Highlands near the city of Nagano, in 1930 by Yokouchi and Koidzumi, and it was named after the area in which it was discovered. The inner perianths of this iris are an intermediate type between its two parents. [15]
Named cultivars of I. setosa include:
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Medicinal and other uses
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Herbalists have used the rhizome of Iris setosa for centuries as an ingredient in various medicines (similar to the usage of Orris roots).[12] However, all parts of Iris setosa are poisonous raw. The rhizome contains iridin, which is an oleoresin and can affect the liver and digestive organs and cause vomiting, diarrhea, or allergic reactions such as severe rashes.[12][31] It has been used by Alaska Natives as an ingredient in a poison to put on arrowheads.[14]
Although poisonous raw, the plant's starchy roots can be made safe for human consumption via cooking,[53][54][55] and the plant is cultivated in Japan for these edible roots.[56]
Some Inuit tribes in Alaska also roasted and ground the seeds of the iris to be used as a coffee substitute.[55][57][58]
The Aleuts made a drink from the roots to be used as a laxative,[59] although the Iñupiat considered the whole plant poisonous.[14]
Some traditional healers made the roots into a tincture used in very small amounts to help soothe lymphatic swelling.[12]
The plant was also combined with Arnica to make an herbal oil to relieve bruises.[12]
The flower petals can be used to create a violet-blue dye, when it is used with a chrome mordant (or fixing agent).[12][59] They are also were used[clarification needed] as a grass dye for baskets.[14] The rhizomes can also be used to extract a perfume (similar to the essence of violets).[13]
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