Iris sibirica (Siberian iris)

Siberian iris is native to central and eastern Europe, ranging from north-eastern Turkey, European Russia and western Siberia in the east, to northern Italy in the west. It has become naturalised in other temperate regions, such as the British Isles and North America.

Iris sibirica (Image: RBG Kew)

Iris sibirica has a rhizome (horizontal underground stem) and hollow, frequently branched, somewhat compressed vertical stems measuring 50—120 cm high. The leaves are green, and there are usually a few small ones on the stem in addition to several basal leaves measuring 25—80 cm x 4—10 mm. Each plant bears 1—3 (rarely 5), mid-blue to violet-blue (rarely white) flowers, measuring 5—7 cm in diameter. The pedicels measure up to 10 cm. The spathes (sheathing bracts) are brown and membranous at the time of flowering, and measure 2.5–5 cm. The perianth tube (formed by the petals and sepals) measures 4—7 mm. The falls (sepals of an iris) are 3—7 cm long, oblong to obovate (egg-shaped) and generally have a paler zone in the centre. The limbs (the expanded part of a corolla that has united petals) are obovate to orbicular in shape. The standard (the upper and usually largest petal) measures 2.5—6 x 1.2—2 cm, and is erect and narrowly obovate to elliptic. The style branches measure 3—4 x 0.5—0.8 cm and have erect, rounded to crenate lobes. The fruit is a capsule 2—4 cm long with an ellipsoidal to sub-cylindrical shape. The seeds are flat.

Flowers are borne between May and July, and the seeds ripen between August and September. The flowers are hermaphroditic (have both male and female organs) and are pollinated by insects. The plant is capable of self-fertilisation.

There are many cultivars of Siberian iris, and also hybrids with the blood iris (Iris sanguinea), ranging in flower colour from white to pale blue, dark blue, mauve and violet.

Globally, Iris sibirica has an extensive range, and is likely to be of Least Concern according to IUCN Red List criteria, although this has not been verified by a formal conservation assessment.

Iris sibirica (Image: RBG Kew)

Iris sibirica grows well in moist or boggy ground and makes an attractive addition to the woodland garden or the margins of ponds and streams.

Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

Description of seeds: Average 1,000 seed weight = 15.8 g.
Number of seed collections stored in the Millennium Seed Bank: Two.

Siberian iris can be seen growing in the Rock Garden at Kew and the Iris Dell at Wakehurst.

A spirit-preserved specimen of Iris sibirica is held in the Herbarium, one of the behind-the-scenes areas of Kew. The details of this specimen can be seen on-line in the Herbarium Catalogue.

In 2011, Kew partnered with The Times to produce a show garden to showcase the significance of plants to science and society.

The garden, designed by Chelsea gold medallist Marcus Barnett, featured species chosen to demonstrate both beauty and utility, including medicinal, commercial, and industrial uses to underline the fact that plants are invaluable to our everyday lives – without them, none of us could live on this planet; they produce our food, clothing and the air that we breathe.

Iris sibirica is the wild relative of the cultivar Iris sibirica 'Dreaming Yellow', which is featuring in Kew’s garden at Chelsea. A cultivar is a cultivated variant of a species, which is often called a ‘variety’ in the horticultural trade. Cultivars usually have characteristics that make them more desirable to growers, for example a carrot that is sweeter than its wild relative or a rose with less thorns than its wild counterpart. 

- Find out more about the 2011 Chelsea Flower Show

- Browse some of the other plants that featured in the garden

Search Kew's databases for more information on this species

Kew Science Teams - Monocots I: General Alismatids & Lilioids

The British Iris Society

The American Iris Society