Iris delavayi is a species in the genus Iris, also the subgenus of Limniris and in the Iris series Sibiricae. It is a rhizomatous herbaceous perennial.

Iris wilsonii is pronounced as EYE-ris del-uh-VAY-ee.^[2]

It is written as 长葶鸢尾 in chinese script and known as chang ting yuan wei in China.^[3][4]

It has the common name of Delavayi Iris^[5][6][7] or long scape iris ^{[4][8][9][10]}

or Chinese Stream Iris (in Australia)^[11]

The Latin specific epithet delavayi refers to the 19th century French missionary Père Jean Marie Delavay.^[12][13]

It was originally found in the marshes in the Yunnan province of China. Seeds of the iris were then sent by Abbé Delavay to the Jardin des Plantes in 1889. Plants were then raised by Micheli,^[5] who then first published and described the iris in Revue Horticole (résumé de tout ce qui parait d'intéressant en jardinage, of Paris) Vol. 67, page 938, in 1895.^[14][4] It was also published in 'Jardin du Crest' page189.^[15] On 1 June 1899, Sir Joseph Dalton Hooker wrote about the iris in Curtis's Botanical Magazine, Tab. 7661, accompanied with a colour illustration. Based on flowers raised from seed given to Kew Gardens by Micheli. Noting the fact the iris was similar in form to Iris laevigata Fisch & Mey.^[5]

This plant has gained the Royal Horticultural Society's Award of Garden Merit.^[6]

Like many other irises, most parts of the plant are poisonous (rhizome and leaves), if mistakenly ingested can cause stomach pains and vomiting. Also handling the plant may cause a skin irritation or an allergic reaction.^[2]

An illustration of iris delavayi has been used as a Postage stamp in Cambodia.^[10]

The iris has been studied to work out its iridal properities. From Iris delavayi collected in the north-western Yunnan Province of China, eight iridal-type triterpenoids were isolated, three of which were new. Both 2(7)Z- and 2(7)E-iridals were isolated in about equal amounts from the sample collected at Laojunshan, while only 2(7)Z-iridals were isolated from samples collected in Shangrila area, indicating the presence of chemical diversity in the species. PMID:  ^[16]

The authors of the 'Flora of China' have speculated that the specimens Iris laevigata Fisch. Found in the high elevations of Yunnan should be referred to Iris delavayi.^[17]

As most irises are diploid, having two sets of chromosomes. This can be used to identify hybrids and classification of groupings.^[18] It has a chromosome count of 2n=40.^{[3][18][19][20][21]} discovered by Simonet 1932.^[5] This places it within the sub-group of the series, called the Sino-siberians.^[18]

The Sino-siberian irises all generally have similar cultivation requirements with minor alterations.

They are not as hardy as the other group of Siberian irises.^[18] They also don't like very hot conditions either. Preferring the northern parts of America and United States to the over warm southern America.^[18] They are considered easy to cultivate (providing the conditions are good) in America.^[15]

Iris delavayi will tolerate temperatures of up to – 15 degrees C.^[22] But may survive lower if protected or well mulched in winter.^[18] It is hardy to USDA Zone 5-8,^[2][7] and Zone H2 (which means Hardy to -15 to-20oC (5 to -4oF ^[23]), in Europe.^[24]

They prefer soils with a ph level of 5.5 to 7 (acidic to neutral ).^[2] They can be grown in any good garden soil that is preferably moist but not waterlogged.^{[6][15][19][25][22] [2][7][13]}

They do not like free-draining soils (or sandy soils),^[18] unless plenty of well-rotted organic matter is added before planting and applied as a mulch each spring.^[6] They are also tolerant of windy conditions.^[25]

They prefer positions in full sun,^[2] but may tolerate partial shade.^[7] They produce less flowers in shaded positions.^[25]

They can be mulched with peat or garden compost in spring.^[26][25] They can also be fed in spring with a general fertiliser but it is not essential.^[18]

They can be divided after flowering (in early summer) or autumn (in the UK^[6]) if the clumps become too big and congested.^[26][7] Also propagation is best carried out by division of the rhizomes.^[25][6]

They then should be replanted 25cm (10ins) apart and 10cm (4inches) deep,^[26][25] into weed free conditions. New plants can be planted in spring or autumn.^[18][25] But the ground needs to be prepared before planting. New plants need to be well watered during the first season.^[25] New plants also take at least 2 years to become established.^[18]

They can also be propagated by seed. Once the pods are dry on the plant, break them open to collect seeds. Then direct sow outdoors in fall (or Autumn), or winter sow in vented containers, in a cold frame or unheated greenhouse.^[2]

They can be used within in gardens, at waterside locations beside pools or streams.^[19][7][6] It can also be used within a bog garden and flowers after Iris sibirica, so extending the flowering season of the garden.^[13]

Rhizomes creeping, thick, ca. 1 cm in diam. ^[3]

Leaves grayish green, reddish at base, sword-shaped or linear, 50--80 × 0.6--1.5 cm, midvein absent, base surrounded by persistent fibers. ^[3]

Flowering stems shortly 1- or 2-branched near apex, 0.6--1.5 m × 5--7 mm, hollow, 3- or 4-leaved; ^[3]

spathes 2 or 3, green, tinted light reddish purple, broadly lanceolate, 7--11 × 1.8--2 cm, 2-flowered, apex acuminate.Fl. May--Jul, ^[3]

Flowers dark violet, ca. 9 cm in diam.; pedicel 3--6 cm. Perianth tube 1.6--1.8 cm; outer segments obovate, with central, dark purple- and white-mottled pattern, ca. 7 × 3 cm, apex retuse; inner segments obliquely spreading, oblanceolate, ca. 5.5 cm. ^[3]

Filaments pale purple; anthers milky yellow. Ovary 1.8--2 cm × ca. 7 mm. Style branches pale purple, ca. 5 × 1.6 cm. Capsule cylindric to ellipsoid, 5--6.5 × 1.5--2.5 cm, 3-angled, apex not beaked. Seeds reddish brown, semiorbicular, flat, ca. 6 mm in diam. fr. Aug--Oct. ^[3]

is a rhizomatous flowering plant in the genus Iris. It is native to south-west Sichuan and Yunnan province in China. It is cultivated as an ornamental plant in temperate regions. It grows to 1.5 metres (4 ft 11 in), with lanceolate leaves, producing several flowers in spring. The flowers range from white to deep blue, with white and yellow markings on the falls.^[27] I. delavayi is a vigorous clump-forming rhizomatous perennial to 1.5m tall, with narrow leaves and branched stems bearing dark purplish-blue flowers 8cm wide, each fall with a large white patch and yellow haft^[6]

Descr.-Rootstock stout, creeping. Leaves two to two and a half feet long, by one half to two-thirds of an inch broad, strict, erect, narrowly linear, acuminate, strongly ribbed. Peduncle longer than the leaves, erect, flexuous, with two or three very narrow leaves, forked at the top. Spathes two to two and a half inches long, lanceolate, herbaceous, green, with scarious tips. Pedicels about as long as the spathes. Perianth two to two and a half inches across the segments, tube half an inch long; outer segments recurved, limb oblong, obtuse, deep violet blue, with tortuous white streaks in the lower half; claw as long as the limb, green, with violet white-spotted wings; inner segments erect, oblong-lanceolate, sub-acute, paler violet. Anthers linear, yellow; stigmas oblong, pale, violet, crests orbicular, crenulate. Capsule two and a half inches long, triquetrous.^[5] 60" (150 cm); B; Flowers light or dark purple, signal large, white. ^[5]

hollow stem, green fruit has a stout creeping rootstock, leaves 2-2.5 ft long by 0.5-0.66 inches broad, erect acuminate and stongly ribbed. Spathes 2 – 2.5 inches long, lanceolate, green with scarious tips, flowers are 2 2.5 inches across, tube 0.5in long, falls recurved, blade oblong, obtuse, deep violet blue with white streaks, haft as long as the blade, green with violet-white spotted wings, standards erect, oblong, lanceolate or paler violet colour, stigmas oblong, pale violet, crests orbicular, crenulate, capsule 2 – 2.5 inches long triquetrous^[15] flowering in july and aug (in UK june) forms large clumps leaves up to 90cm shorter than the stems stems up to 1.5m tall with1-3 branches flowers 2 per branch – light to dark purplish-blue with a large white patch on the blade of the falls, standards at an oblique angle not upright,^[22] A clumping, herbaceous perennial, reaching a maximum size of 5 x 4+ feet, The leaves, up to 40 x 1 inches, are green. The violet-purple ( marked white ) flowers, up to 4 inches across, are borne on slender stems during early summer.^[7] smalll purple-blue butterfly-like flowers with centres finely veined over white flowering in late spring^[11] General Description: 24"-47" (60-120cm) tall, with light or dark blue flowers with white signal ^[20] 24”-47" (60-120 cm). Light to dark blue violet; white signal.^[21] Height: 18-24 in. (45-60 cm) Spacing: 18-24 in. (45-60 cm) Bloom Color: Dark Blue, Blue-Violet Bloom Time: Late Midseason (MLa)^[2] 90-150cm stems unbranched hollow, leaves grey-green shorter than the flowering stems, bracts green, papery at the tips, flowers 7-9cm in diameter, falls pale or dark purple, the circular blade notched at the apex, with a large white patch in the centre, standards similar in ground colour, held at an oblique angle summer^[24] plant stout to 150cm tall, forming large tufts, the stems considerably longer then the leaves, leaves – grey-green on both surfaces, usually 0.6-1cm wide, stems generally with 2-3 short branches, spathes foliaceous with brown tips at flowering time each pair bearing 2 flowers 7-9cm diameter, deep violet with a conspicuous 'broken' white signal patch in the centre of the falls, standards oblanceolate, inclined at an oblique angle^[28] This fine species is larger and stronger than I. sibirica and grows to a height of three or four feet or even more in rich, moist soil. It agrees with I. sibirica in having a hollow tubular stem but has broader leaves and long, green spathes, of which the outer valve is longer than the inner. The blade of the fall is longer and larger than that of I. sibirica and the white ground shows plainly in rather large and often oblong blotches, unobscured by any network of veins. The standards are rather narrow and extend at an angle of 45 degrees, instead of standing erect or even inclining inwards as do those of I. sibirica. The colour in the specimens first introduced was always a rich red-violet but in others raised from seeds sent home by Wilson there is considerable variation in all shades of blue and red-purple. flowers late in June and July^[13]

Iris delavayi is native to south western China.^[20][21]

It is found in the chinese provinces of Guizhou, Sichuan (formerly known as Sze-chuen^[13]), Xizang and Yunnan.^{[3][22][4][7][28][15]} It can also be found in Bhutan.^[28]

From Iris delavayi collected in the north-western Yunnan Province of China, Laojunshan, Shangrila ^[16]

It can be found growing in swampy places,^[13] mountain marshes,^[15] forest margins,^[3] damp places along ditches and streams,^[3][11][28] and wet mountain meadows.^{[22] [3][7][28]} At altitudes of between 2400-4500m.^[3][22][28]

It can spread in ideal conditions to create large colonies.^[15]

Iris delavayi can be crossed with Iris wilsonii which gives its yellow base colour (veined with bluish purple^[24]) to the flowers and it can also cross with other members of the sibirica subsection.^[13]

Known Iris delavayi selections include: 'Delavayi Pallida', 'Didcot', 'Thibet'.^[5] Iris delavayi crosses also include; 'Berliner Riesen', 'Black Pirate', 'Delfor', 'Diamond Jubilee', 'Diomed', 'Far Voyager', 'Fifinella', 'Lightly Touched', 'Normal', 'Ormonde', 'Persimmon'.^[5]

A known cultivar is Iris delavayi 'Didcote'^[29]

• Aldén, B., S. Ryman & M. Hjertson. 2009. Våra kulturväxters namn - ursprung och användning. Formas, Stockholm (Handbook on Swedish cultivated and utility plants, their names and origin).
• Chinese Academy of Sciences. 1959–. Flora reipublicae popularis sinicae.
• Mathew, B. 1981. The Iris. 89.
• Waddick, J. W. & Zhao Yu-tang. 1992. Iris of China.
• Wu Zheng-yi & P. H. Raven et al., eds. 1994–. Flora of China (English edition).

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