Iris tectorum | |
---|---|
| |
Wall iris (Iris tectorum) | |
Scientific classification
![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Asparagales |
Family: | Iridaceae |
Genus: | Iris |
Subgenus: | Iris subg. Limniris |
Section: | Iris sect. Lophiris |
Species: | I. tectorum
|
Binomial name | |
Iris tectorum | |
Synonyms [1] | |
|
Iris tectorum (also known as roof iris, Japanese roof iris and wall iris) is a plant species in the genus Iris, it is also in the subgenus Limniris. It is a rhizomatous perennial. It is native of China, Korea and Burma, with lavender-blue, bluish-violet, purple-blue, blue-lilac or sky blue flowers. There is a white form as well. It is a compact plant and is cultivated as an ornamental plant in temperate regions of the world.
It has a thick, [2] [3] [4] (the size of a man's thumb), [5] creeping, [5] [6] buff (coloured), [7] or greenish rhizome. [8] [9] They are similar in form to a bearded iris rhizome. [10] [11] It has slender, short roots (under the rhizomes), [7] [12] and fibres on the top. [12] The creeping habit, creates spreading clumps of plants. [13] [14] [15] It does not produce stolons. [5]
It has basal fans, [16] [17] [18] that are yellowish green, [12] or pale green, [19] [20] [21] and sword-shaped (ensiform), [9] [22] [23] or lance-shaped. [7] [3] [24] They are also, glossy, [5] [23] [14] and ribbed, [7] [18] [25] and can grow up to between 15–60 cm (6–24 in) long and 1.5–5 cm (1–2 in) wide. [18] [26] [27] The leaves are floppy, [22] [21] and described as semi- evergreen. [24] [26] [22]
It has terete (cylindrical), [6] stems that can grow up to between 20–45 cm (8–18 in) tall. [28] [29] [30] It has 1–2 branches, [8] [21] [26] and 1–2 (reduced) stem leaves. [7] [5] [31]
The stems have 2–3 spathes (leaves of the flower bud), that are green, [6] lanceolate and 3.5–7.5 cm (1–3 in) long and 2–2.5 cm (1–1 in) wide. [12] [5]
It has a 1 cm long pedicel (flower stalk), [12] which is shorter than the spathe, [5] but similar in size to the ovary. [6]
The stems (and the branches) hold between 1 and 3 flowers, [31] [26] [32] in late spring, [14] [17] [28] or early summer, [2] [17] [20] between April and May, [26] [33] [34] or June. [18] [21] [33] It flowers between September and October in Australia. [16] The flower display can last for 2 weeks. [22] The flowers are 7.6–10 cm (3–4 in) in diameter, [28] [35] [36] The flattened, [25] [27] [32] horizontal, [37] flowers are larger than Iris japonica flowers. [38]
The flowers come in shades of lavender blue, [32] [30] [37] or bluish violet, [19] [30] [38] or blue-lilac, [25] [39] [36] or purple-blue, [24] [31] [25] or sky blue. [29] [18] [35] There is also a white form. [30] [37] [38]
It has 2 pairs of petals, 3 large sepals (outer petals), known as the 'falls' and 3 inner, smaller petals (or tepals), known as the 'standards'. [4] [9] The falls are obovate (egg-like), [10] [6] or ovate, [12] with darker (or brownish purple/violet). [9] mottling, [2] [18] [25] veining, [8] [23] [39] streaks, [6] [9] or spots, [2] [10] [4] [24] around a toothed or lacinated (fringed), [7] [5] white crest. [39] [36] [38] They have a bi-coloured claw (part of the petal closest to the stem), white and violet or lilac. [5] [6] The falls are 5–7 cm (2–3 in) long and 4 cm wide. [5] [8] [31] The elliptic standards spread horizontally (not erect), [8] [21] [25] and are 4.5–5 cm (2–2 in) long and 3 cm wide. [12] [10] Both petals (falls and standards) can have wavy margins. [4] [21] [33]
The flowers are self-fertile, [7] but are pollinated by insects. [23]
It has a 2.5–3 cm long slender, perianth tube, [5] [6] [8] a 2.5 cm long stamen, bright yellow anthers and a cylindric, 1.8–2 cm long ovary. [12] It has a pale bluish-violet style branch, that is 3.5 cm long. [12] It has toothed lobes (at the tips), that are irregular. [6] [8]
After the iris has flowered, between June and August, [12] [19] it produces an ellipsoid or obovoid (oblong-ovoid), [12] [7] light green, [14] seed capsule. [9] [31] It is 4.5–6 cm (2–2 in) long and 2–2.5 cm wide, [12] [7] [31] and has 6 ribs. [7] When it ripens, (and goes brown, [23]) it splits in three, along 2 or more seams, starting from the top. [7] [31] Inside, are multiple, [23] [31] black-brown seeds, [12] [23] which are pyriform (pear shaped) and have a small cream (coloured) aril (appendage). [12] [7]
In 1994, a study was carried out to isolate various chemical compounds from the seeds of Iris tectorum, it found an ester ' iristectorene B'. [40]
In 1999, a study was carried out Iris tectorum rhizomes, it found a triterpenoid chemical compound. [41]
In 2007, a study was carried out on cytotoxic properties of Iris tectorum, used to treat cancer. [42]
In May 2007, a study was carried out on the rhizomes of Iris tectorum, to find various chemical compounds. [43]
In 2009, a karyotype analysis was carried out on 10 Irises found in China, and found that Iris tectorums was 2n=28. [44]
In 2011, Isoflavones such as tectoridin, iristectorin B and iristectorin A have been found in the rhizomes of Iris tectorum. They were published in the Journal of Chromatography B, Vol. 879, Issue 13, pages 975–980. [45]
In 2012, a study was carried out on the leaves of Iris tectorum for anti cancer properties. [46]
In 2013, a study was carried on Iris tectorum to isolate various chemical compounds. [47]
In 2013, a molecular phylogenetic (genetic evolution) study was carried out on 16 species of Iris found in Korea. It placed Iris mandshurica in a clade with other basal irises, including Iris dichotoma and Iris tectorum. [48]
In January 2014, a study was carried out on the neuro-protective activities of Iris tectorum. [49]
Several isoflavones have been found in Iris tectorum. Iris tectorigenin A is found in Iris florentina, Iris tectorum, Iris pseudacorus, Iris kumaonensis and Belamcanda chinensis ( iris domestica). Iristectorin B (C23H24O12) can be found in the rhizomes of Iris tectorum, iris-tectorigenin B found in Iris germanica and Iris tectorum and iristectorin A (which is also found in Belamcanda chinensis). [50]
As most irises are diploid, having two sets of chromosomes, this can be used to identify hybrids and classification of groupings. [4] Diploid counts include 2n=28, Simonet, 1932; 2n=32, Sharma, 1970; 2n=28, Chimphamba, 1973; 2n=28, Karihaloo, 1978; 2n=28, Karihaloo, 1984; 2n=28, Huiang, 1986; 2n=36, Mao & Xue, 1986; 2n=28, Huang 1989; and 2n=32, Dong et al., 1994. [6] It is normally designated as 2 n = 24, 28, 32. [12] [7] [39]
It is pronounced as (Iris) EYE-ris (tectorum) tek-TOR-um. [28] [30]
It is written as 鸢尾 in Chinese script, [12] and known as yuan wei in Pidgin in China. [17] [51] [52]
It has several common names, including; roof iris, [52] [53] [54] Japanese roof iris, [30] [37] [53] wall iris (in America), [54] [55] [56] wall flag, [3] white root iris, [20] [30] Ichihatu (In Japan – meaning first as the first iris to flower), [57] [58] shenan, [51] [52] and roof garden iris. [32]
It is known as Dach-Schwertlilie in German and takiris in Swedish. [51] [52]
The Latin specific epithet tectorum refers to Latin word for roof or covering. [21] [59]
Iris tectorum is native to China, but was first discovered in the 1860s, growing in Japan on the roofs, hence the common name. [22]
It was first published and described by Karl Maximovich in the 'Bulletin of Acad. Imp. Sci. Saint-Pétersbourg' Volume15 page380 in 1871. [5] [51] [60]
It was published in Flor. Serres Vol.22 page 23 in 1874, with a colour illustration, [6] then published by Hooker in Curtis's Botanical Magazine table 6118 in September, 1874, [5] [6] and in the 'Journal of the Royal Horticultural Society' Vol88 page116 in 1963. [8]
It was introduced to England and European cultivation in 1874, [4] [6] by Philipp Franz von Siebold, who sent plants to St Petersburg. [7] It was also introduced to US cultivation by Mr William Bull in 1874. [5] [32]
It was verified by United States Department of Agriculture and the Agricultural Research Service on 2 April 1996 and updated on 1 December 2004. [51]
Iris tectorum is an accepted name by the RHS. [53]
It is native to temperate and tropical regions of Asia. [11] [51] [52]
It is found in (central and south western), [7] [2] [61] China, [36] [52] [53] within the Chinese provinces, of Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shanxi, Sichuan, Xizang, Yunnan and Zhejiang. [12] [51]
Also found in Korea, [39] [51] [61] and within (the tropical region) of Myanmar (Burma). [51] [56] [61]
It is often cited as native to Japan, [19] [32] [54] but it may just be naturalized. [2] [10] [26]
It has naturalized in Bhutan and India. [15] It has also naturalized in regions of America, including New Hampshire. [55]
It grows on forest margins, on sunny banks, in meadows, in damp places and beside water. [23] [15] [19] It can also be found growing along roadsides and on steep hillsides, in China. [4] [26]
They can be found at an altitude of 500–3,500 m (1,600–11,500 ft) above sea level. [12] [11] [15]
In New Hampshire, as a wild flower, it is found on the edges of lawns and fields, beside roadsides and in compost heaps. [55]
The cultivation of Iris tectorum is very similar to that of Iris japonica and Iris milesii. [32]
It is hardy to between USDA Zone 4 and Zone 9. [28] [30] [54] It is hardy to European Zone H2, [8] meaning it can tolerate temperatures as low as −10, [11] but needs protection from hard frosts. [35] Older plants can survive some frosts but young plants need protection in the spring. [36] Both the blue and white forms of the iris, are perfectly hardy. [5] [32] It is hardy in the UK, [3] but it does not flower very well, due to the summers not being hot enough to bake the roots. [34] After flowering, it is best to remove the old stems from Iris confusa, Iris japonica and Iris tectorum, as this helps the plant survive the winter. [11] [62]
It prefers to grow in humus, rich, [27] [35] [56] moist soil, [28] [54] [56] with good drainage. [27] [36] [56]
During spring or autumn, a top dressing of well rotted compost (or well rotted manure), [10] should be added, [7] [36] a feed of fertilizer can also be added. [10] [16] [27] A mulch can also be applied (at the same time) to retain the moisture. [35] [56]
It can tolerate neutral or acidic soils ( pH levels between 6.1 – 7.8). [20] [27] [28]
It can tolerate positions between full sun and partial shade, [54] [56] [61] but prefers light shade, [19] [38] [54] In full sun, the leaves can bleach. [10] (similar to woodland conditions). [16] Although, a few sources say it prefers a sunny, sheltered site. [2] [36] [56]
It has average water needs during the growing season. [16] [14] [20] If the summer conditions become exceedingly hot and dry, the iris will go into early dormancy. [23] Therefore it prefers a dry and cold winter, with a warm and wet summer. [5] [26] [36]
It can be grown in a mixed flower border, [14] [20] [27] rock garden, [23] [14] [20] and in a woodland garden. [9] [23] [27] If the plant is to be grown in a rockery, it is recommended that the plant has new soil or fertiliser every year. [36] It can be also grown in containers and large (15 cm) pots, [7] [14] [20] but it needs to be re-potted frequently. [4] In the UK, the pot can survive the winter in a cold greenhouse. [7]
It suffers from a virus disease that causes leaf discolouration, [7] [2] [11] yellowing and streaking. [10] It seems immune to insect pests, [22] [24] but can be prone to damage from slugs or snails. [11] [27] Also an aphid, Aulacorthum solani can be found on the plant. [63]
Since the roots can quickly take all the nutrients out of the soil, division and re-planting is needed every other year, [7] [24] or every 3–5 years when clumps become over-crowded. [4] [13] [16] Although, it can be left undisturbed for many years, but flowering will decrease. [38]
Like most rhizomatous irises, it should be planted with the top of rhizome just at the surface of the soil. [13] [22] [24] They should be spaced 20–30 cm (8–12 in) apart. [13] [28] [30]
Iris tectorum can be propagated by division or by seed growing. [22] [24] [36] It is easy to raise from seed. [7] [24] [37]
Plants grown from its seeds will re-produce a true form, including white plants. [36]
Division is best done in the spring, [9] [36] or fall (after flowering). [11] [9] [27] Transplanting should be carried out soon after division. [25]
Iris tectorum has many cultivars including;
Like many other irises, most parts of the plant are poisonous (rhizome and leaves), if mistakenly ingested, it can cause stomach pains and vomiting. Also handling the plant may cause a skin irritation (like dermatitis or an allergic reaction. [11] [9]
Despite its toxicity, it is used in Chinese herbal medicine to treat hepatitis and wind damp pains. [65]
The Kam eat fish that have been given fresh Iris tectorum, as medicine to treat stomach aches. [66]
Iris tectorum is commonly called the 'roof iris' because it was grown in the thatch of Chinese and Japanese houses. [33] [35] [38] There are several theories as to why;
The most common theory, was due to a period of wartime, [22] or great famine in Japan, all land was then decreed by the emperor to be cultivated, for rice and other food crops. [16] [27] [34] Also, it was illegal for land to be used for growing flowers. [10] [22] [27] But also women wanted the iris roots for making hair dye, face powder and corn plasters. [38] The rhizomes were ground down, [22] [54] to make a white powder used for whitening the skin, [10] [11] [34] similar in look to Geisha girls. [22] [27] Although, EA bowles did not believe this theory. [38]
Another theory, was that it was grown in the wet clay and was used to bind the straw thatch together, to stop a roof coming apart. [10] [23] [16] It also acted as a decoration, creating a purple flowering roof-ridge. [23]
A final reason known, was that it was planted to avert the 'evil spirits' and a superstition that they prevent disease from affecting the householders. [10] [34]
Iris tectorum | |
---|---|
| |
Wall iris (Iris tectorum) | |
Scientific classification
![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Asparagales |
Family: | Iridaceae |
Genus: | Iris |
Subgenus: | Iris subg. Limniris |
Section: | Iris sect. Lophiris |
Species: | I. tectorum
|
Binomial name | |
Iris tectorum | |
Synonyms [1] | |
|
Iris tectorum (also known as roof iris, Japanese roof iris and wall iris) is a plant species in the genus Iris, it is also in the subgenus Limniris. It is a rhizomatous perennial. It is native of China, Korea and Burma, with lavender-blue, bluish-violet, purple-blue, blue-lilac or sky blue flowers. There is a white form as well. It is a compact plant and is cultivated as an ornamental plant in temperate regions of the world.
It has a thick, [2] [3] [4] (the size of a man's thumb), [5] creeping, [5] [6] buff (coloured), [7] or greenish rhizome. [8] [9] They are similar in form to a bearded iris rhizome. [10] [11] It has slender, short roots (under the rhizomes), [7] [12] and fibres on the top. [12] The creeping habit, creates spreading clumps of plants. [13] [14] [15] It does not produce stolons. [5]
It has basal fans, [16] [17] [18] that are yellowish green, [12] or pale green, [19] [20] [21] and sword-shaped (ensiform), [9] [22] [23] or lance-shaped. [7] [3] [24] They are also, glossy, [5] [23] [14] and ribbed, [7] [18] [25] and can grow up to between 15–60 cm (6–24 in) long and 1.5–5 cm (1–2 in) wide. [18] [26] [27] The leaves are floppy, [22] [21] and described as semi- evergreen. [24] [26] [22]
It has terete (cylindrical), [6] stems that can grow up to between 20–45 cm (8–18 in) tall. [28] [29] [30] It has 1–2 branches, [8] [21] [26] and 1–2 (reduced) stem leaves. [7] [5] [31]
The stems have 2–3 spathes (leaves of the flower bud), that are green, [6] lanceolate and 3.5–7.5 cm (1–3 in) long and 2–2.5 cm (1–1 in) wide. [12] [5]
It has a 1 cm long pedicel (flower stalk), [12] which is shorter than the spathe, [5] but similar in size to the ovary. [6]
The stems (and the branches) hold between 1 and 3 flowers, [31] [26] [32] in late spring, [14] [17] [28] or early summer, [2] [17] [20] between April and May, [26] [33] [34] or June. [18] [21] [33] It flowers between September and October in Australia. [16] The flower display can last for 2 weeks. [22] The flowers are 7.6–10 cm (3–4 in) in diameter, [28] [35] [36] The flattened, [25] [27] [32] horizontal, [37] flowers are larger than Iris japonica flowers. [38]
The flowers come in shades of lavender blue, [32] [30] [37] or bluish violet, [19] [30] [38] or blue-lilac, [25] [39] [36] or purple-blue, [24] [31] [25] or sky blue. [29] [18] [35] There is also a white form. [30] [37] [38]
It has 2 pairs of petals, 3 large sepals (outer petals), known as the 'falls' and 3 inner, smaller petals (or tepals), known as the 'standards'. [4] [9] The falls are obovate (egg-like), [10] [6] or ovate, [12] with darker (or brownish purple/violet). [9] mottling, [2] [18] [25] veining, [8] [23] [39] streaks, [6] [9] or spots, [2] [10] [4] [24] around a toothed or lacinated (fringed), [7] [5] white crest. [39] [36] [38] They have a bi-coloured claw (part of the petal closest to the stem), white and violet or lilac. [5] [6] The falls are 5–7 cm (2–3 in) long and 4 cm wide. [5] [8] [31] The elliptic standards spread horizontally (not erect), [8] [21] [25] and are 4.5–5 cm (2–2 in) long and 3 cm wide. [12] [10] Both petals (falls and standards) can have wavy margins. [4] [21] [33]
The flowers are self-fertile, [7] but are pollinated by insects. [23]
It has a 2.5–3 cm long slender, perianth tube, [5] [6] [8] a 2.5 cm long stamen, bright yellow anthers and a cylindric, 1.8–2 cm long ovary. [12] It has a pale bluish-violet style branch, that is 3.5 cm long. [12] It has toothed lobes (at the tips), that are irregular. [6] [8]
After the iris has flowered, between June and August, [12] [19] it produces an ellipsoid or obovoid (oblong-ovoid), [12] [7] light green, [14] seed capsule. [9] [31] It is 4.5–6 cm (2–2 in) long and 2–2.5 cm wide, [12] [7] [31] and has 6 ribs. [7] When it ripens, (and goes brown, [23]) it splits in three, along 2 or more seams, starting from the top. [7] [31] Inside, are multiple, [23] [31] black-brown seeds, [12] [23] which are pyriform (pear shaped) and have a small cream (coloured) aril (appendage). [12] [7]
In 1994, a study was carried out to isolate various chemical compounds from the seeds of Iris tectorum, it found an ester ' iristectorene B'. [40]
In 1999, a study was carried out Iris tectorum rhizomes, it found a triterpenoid chemical compound. [41]
In 2007, a study was carried out on cytotoxic properties of Iris tectorum, used to treat cancer. [42]
In May 2007, a study was carried out on the rhizomes of Iris tectorum, to find various chemical compounds. [43]
In 2009, a karyotype analysis was carried out on 10 Irises found in China, and found that Iris tectorums was 2n=28. [44]
In 2011, Isoflavones such as tectoridin, iristectorin B and iristectorin A have been found in the rhizomes of Iris tectorum. They were published in the Journal of Chromatography B, Vol. 879, Issue 13, pages 975–980. [45]
In 2012, a study was carried out on the leaves of Iris tectorum for anti cancer properties. [46]
In 2013, a study was carried on Iris tectorum to isolate various chemical compounds. [47]
In 2013, a molecular phylogenetic (genetic evolution) study was carried out on 16 species of Iris found in Korea. It placed Iris mandshurica in a clade with other basal irises, including Iris dichotoma and Iris tectorum. [48]
In January 2014, a study was carried out on the neuro-protective activities of Iris tectorum. [49]
Several isoflavones have been found in Iris tectorum. Iris tectorigenin A is found in Iris florentina, Iris tectorum, Iris pseudacorus, Iris kumaonensis and Belamcanda chinensis ( iris domestica). Iristectorin B (C23H24O12) can be found in the rhizomes of Iris tectorum, iris-tectorigenin B found in Iris germanica and Iris tectorum and iristectorin A (which is also found in Belamcanda chinensis). [50]
As most irises are diploid, having two sets of chromosomes, this can be used to identify hybrids and classification of groupings. [4] Diploid counts include 2n=28, Simonet, 1932; 2n=32, Sharma, 1970; 2n=28, Chimphamba, 1973; 2n=28, Karihaloo, 1978; 2n=28, Karihaloo, 1984; 2n=28, Huiang, 1986; 2n=36, Mao & Xue, 1986; 2n=28, Huang 1989; and 2n=32, Dong et al., 1994. [6] It is normally designated as 2 n = 24, 28, 32. [12] [7] [39]
It is pronounced as (Iris) EYE-ris (tectorum) tek-TOR-um. [28] [30]
It is written as 鸢尾 in Chinese script, [12] and known as yuan wei in Pidgin in China. [17] [51] [52]
It has several common names, including; roof iris, [52] [53] [54] Japanese roof iris, [30] [37] [53] wall iris (in America), [54] [55] [56] wall flag, [3] white root iris, [20] [30] Ichihatu (In Japan – meaning first as the first iris to flower), [57] [58] shenan, [51] [52] and roof garden iris. [32]
It is known as Dach-Schwertlilie in German and takiris in Swedish. [51] [52]
The Latin specific epithet tectorum refers to Latin word for roof or covering. [21] [59]
Iris tectorum is native to China, but was first discovered in the 1860s, growing in Japan on the roofs, hence the common name. [22]
It was first published and described by Karl Maximovich in the 'Bulletin of Acad. Imp. Sci. Saint-Pétersbourg' Volume15 page380 in 1871. [5] [51] [60]
It was published in Flor. Serres Vol.22 page 23 in 1874, with a colour illustration, [6] then published by Hooker in Curtis's Botanical Magazine table 6118 in September, 1874, [5] [6] and in the 'Journal of the Royal Horticultural Society' Vol88 page116 in 1963. [8]
It was introduced to England and European cultivation in 1874, [4] [6] by Philipp Franz von Siebold, who sent plants to St Petersburg. [7] It was also introduced to US cultivation by Mr William Bull in 1874. [5] [32]
It was verified by United States Department of Agriculture and the Agricultural Research Service on 2 April 1996 and updated on 1 December 2004. [51]
Iris tectorum is an accepted name by the RHS. [53]
It is native to temperate and tropical regions of Asia. [11] [51] [52]
It is found in (central and south western), [7] [2] [61] China, [36] [52] [53] within the Chinese provinces, of Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shanxi, Sichuan, Xizang, Yunnan and Zhejiang. [12] [51]
Also found in Korea, [39] [51] [61] and within (the tropical region) of Myanmar (Burma). [51] [56] [61]
It is often cited as native to Japan, [19] [32] [54] but it may just be naturalized. [2] [10] [26]
It has naturalized in Bhutan and India. [15] It has also naturalized in regions of America, including New Hampshire. [55]
It grows on forest margins, on sunny banks, in meadows, in damp places and beside water. [23] [15] [19] It can also be found growing along roadsides and on steep hillsides, in China. [4] [26]
They can be found at an altitude of 500–3,500 m (1,600–11,500 ft) above sea level. [12] [11] [15]
In New Hampshire, as a wild flower, it is found on the edges of lawns and fields, beside roadsides and in compost heaps. [55]
The cultivation of Iris tectorum is very similar to that of Iris japonica and Iris milesii. [32]
It is hardy to between USDA Zone 4 and Zone 9. [28] [30] [54] It is hardy to European Zone H2, [8] meaning it can tolerate temperatures as low as −10, [11] but needs protection from hard frosts. [35] Older plants can survive some frosts but young plants need protection in the spring. [36] Both the blue and white forms of the iris, are perfectly hardy. [5] [32] It is hardy in the UK, [3] but it does not flower very well, due to the summers not being hot enough to bake the roots. [34] After flowering, it is best to remove the old stems from Iris confusa, Iris japonica and Iris tectorum, as this helps the plant survive the winter. [11] [62]
It prefers to grow in humus, rich, [27] [35] [56] moist soil, [28] [54] [56] with good drainage. [27] [36] [56]
During spring or autumn, a top dressing of well rotted compost (or well rotted manure), [10] should be added, [7] [36] a feed of fertilizer can also be added. [10] [16] [27] A mulch can also be applied (at the same time) to retain the moisture. [35] [56]
It can tolerate neutral or acidic soils ( pH levels between 6.1 – 7.8). [20] [27] [28]
It can tolerate positions between full sun and partial shade, [54] [56] [61] but prefers light shade, [19] [38] [54] In full sun, the leaves can bleach. [10] (similar to woodland conditions). [16] Although, a few sources say it prefers a sunny, sheltered site. [2] [36] [56]
It has average water needs during the growing season. [16] [14] [20] If the summer conditions become exceedingly hot and dry, the iris will go into early dormancy. [23] Therefore it prefers a dry and cold winter, with a warm and wet summer. [5] [26] [36]
It can be grown in a mixed flower border, [14] [20] [27] rock garden, [23] [14] [20] and in a woodland garden. [9] [23] [27] If the plant is to be grown in a rockery, it is recommended that the plant has new soil or fertiliser every year. [36] It can be also grown in containers and large (15 cm) pots, [7] [14] [20] but it needs to be re-potted frequently. [4] In the UK, the pot can survive the winter in a cold greenhouse. [7]
It suffers from a virus disease that causes leaf discolouration, [7] [2] [11] yellowing and streaking. [10] It seems immune to insect pests, [22] [24] but can be prone to damage from slugs or snails. [11] [27] Also an aphid, Aulacorthum solani can be found on the plant. [63]
Since the roots can quickly take all the nutrients out of the soil, division and re-planting is needed every other year, [7] [24] or every 3–5 years when clumps become over-crowded. [4] [13] [16] Although, it can be left undisturbed for many years, but flowering will decrease. [38]
Like most rhizomatous irises, it should be planted with the top of rhizome just at the surface of the soil. [13] [22] [24] They should be spaced 20–30 cm (8–12 in) apart. [13] [28] [30]
Iris tectorum can be propagated by division or by seed growing. [22] [24] [36] It is easy to raise from seed. [7] [24] [37]
Plants grown from its seeds will re-produce a true form, including white plants. [36]
Division is best done in the spring, [9] [36] or fall (after flowering). [11] [9] [27] Transplanting should be carried out soon after division. [25]
Iris tectorum has many cultivars including;
Like many other irises, most parts of the plant are poisonous (rhizome and leaves), if mistakenly ingested, it can cause stomach pains and vomiting. Also handling the plant may cause a skin irritation (like dermatitis or an allergic reaction. [11] [9]
Despite its toxicity, it is used in Chinese herbal medicine to treat hepatitis and wind damp pains. [65]
The Kam eat fish that have been given fresh Iris tectorum, as medicine to treat stomach aches. [66]
Iris tectorum is commonly called the 'roof iris' because it was grown in the thatch of Chinese and Japanese houses. [33] [35] [38] There are several theories as to why;
The most common theory, was due to a period of wartime, [22] or great famine in Japan, all land was then decreed by the emperor to be cultivated, for rice and other food crops. [16] [27] [34] Also, it was illegal for land to be used for growing flowers. [10] [22] [27] But also women wanted the iris roots for making hair dye, face powder and corn plasters. [38] The rhizomes were ground down, [22] [54] to make a white powder used for whitening the skin, [10] [11] [34] similar in look to Geisha girls. [22] [27] Although, EA bowles did not believe this theory. [38]
Another theory, was that it was grown in the wet clay and was used to bind the straw thatch together, to stop a roof coming apart. [10] [23] [16] It also acted as a decoration, creating a purple flowering roof-ridge. [23]
A final reason known, was that it was planted to avert the 'evil spirits' and a superstition that they prevent disease from affecting the householders. [10] [34]