Siberian irises (28 chromosome group)

The beautiful hybrids that we grow in our gardens under the common name of siberian iris, have originated from two main species: I. sibirica, and I. sanguinea, and more recently I. typhifolia has also been used in breeding.

I. sibirica despite it’s name, grows naturally in Russia and Central Europe. The narrow green leaves are deciduous, the stems grow to 90cm or more, and are branched, bearing 5 to 10 fluttering violet, blue or white blooms in late Spring. The spathes are green, turning brown and papery later. Standards are small and open, style arms are prominent, curving gracefully, and may be fimbriated. Falls arch and flare horizontally. Signals are gold or white, and the same colour may be present as a fine line around the falls.

I. sibirica hybrid

I. sanguinia does grow in siberia, and has been cultivated in Japan since the 17th century. It has shorter bloom stalks, bearing larger, dark violet blooms, 2 per stem. It interbreeds readily with I. sibirica. It was listed in Dutch catalogues in the late 19th century, and grown in England a few decades later.

I. typhifolia has narrow, slightly twisted leaves, and was named for its similarity to leaves of the cattail genus Typha. It was found and named in the early 19th century, and rediscovered in Mongolia only in the 1980’s. It blooms early and sometimes reblooms. The blooms are large, often without a prominent signal. It likes a damper soil and slightly warmer climate than the others in this group. It has contributed recently to the hybrid gene pool, as a means of introducing earlier bloom, and rebloom.

Hybridisation and selection has led to a broadening of the colour range, with colours including blue, violet, purple, lavender, wine red, white. More recently yellows and pinks have appeared, and new varieties are becoming available that hint of orange and browns.

In the 1960’s, McEwan (USA) and others induced tetraploidy (doubling of the chromosome numbers) to give varieties with stronger substance and improved vigour, but the diploid varieties have remained very popular for their grace and beauty.

With increasing enthusiasm for producing unusual hybrid iris, Siberian iris have been crossed with the not so distant relative I. setosa, to produce Sibtosa’s which are robust and generally taller growing. The popular ‘Sibtosa Princess’ is a good example. They have also been crossed with Pacific Coast Iris, although the PCI’s cross more readily with the 40 chromosome species.

I. setosa