Dwarf Iris

Iris pumila has been shown to be a natural amphidiploid hybrid between I. pseudopumila Boissier & Heldreich and I. attica Tineo, both 2n = 16. Like many other such hybrids, its range of variability is so extensive that many of its forms have been given specific names. In spite of the variability in color and size, it is now recognized as a distinct species. During the past 50 years, it has been crossed repeatedly with several other species, including I. germanica and its mixed progeny, and this has introduced patterns from the tall-bearded iris into the dwarfs, and vice versa. The ranges of flowering season and plant height are now almost continuous from one extreme to the other, and intermediate groups are now recognized.

Iris pumila is widely grown in gardens and often persists for years after cultivation around old dwellings and along roadsides. It is thus extremely difficult to document and map its spontaneous occurrence. Although most, if not all, of the modern dwarf irises are of hybrid parentage, a number of herbarium specimens from the nineteenth century seem to represent wild forms of I. pumila.

Rhizomatous plant 10-15 cm. Leaves glaucous green, broadly linear, 10-15 cm x 1.0-2.0 cm. Flowers solitary, 5-7 cm diam, of various colours (yellow to lilac). V - mid-spring to late autumn (leaves can overwinter). Fl - late spring-early summer, in St. Petersburg May- June. Fr - August. P - by seed and division. Requires a sunny place, however can grow in a shady position. Cultivated since the XVI century and was used for selection of dwarf bearded irises. Z 5 (4).

Rhizomes freely branching, producing dense clumps, 1–1.5 cm diam. Stems absent or not more than 1 cm. Leaves ascending-spreading; blade grayish green, ensiform or slightly falcate, 8–10 cm × 6–15 mm at anthesis, increasing to 15–20 cm in length on innovations after flowering, dying back in autumn, new growth only in spring, glaucous. Inflorescence units 1-flowered, sessile in spathes; spathes 5–10 cm; outer darker green than inner, inner closely shielding floral tube. Flowers: floral tube with 3 purple stripes in line with midrib of petals, slender, 6–10 cm × 2–3 mm, lifting expanded portion of flower out of spathes; sepals yellow, blue, or purple, with yellowish or bluish beard, often with contrasting spot around beard at base of limb, 4–5 × 1.2–2 cm; petals with darker veins near base, rounded-ovate, broader than sepals, 4–5 × 2.2–2.7 cm, narrowing abruptly to brown-veined claw, apex emarginate; ovary rounded-trigonal, ca. 1 cm × 4–5 mm; style crests triangular, margins serrate distally; stigmas rounded on distal margin, margins entire; pedicel absent. Capsules borne on tips of rhizomes at ground level or slightly below, rounded-trigonal, with short portion of dried floral tube forming tip, smooth, 2–3.5 × 1.5–2 cm, dehiscing while green. Seeds usually in 2 rows per locule, light brown, subspherical, 3–5 mm diam., wrinkled. 2n = 30, 31, 32, 36.

European parts of the FSU (southern regions), Caucasus (eastern regions), central and southern Europe. Stony slopes, steppes, on gravelly soil, solonchaks.

Flowering late Mar--mid May. Dry, grassy areas; introduced; Ill., Ind., Mich., Ohio; c, e Europe.

Iris pumila, sometimes known as pygmy iris or dwarf iris, probably originated as a natural hybrid between Iris pseudopumila Boissier & Heldreich and I. attica Tineo. It ranges from Austria through eastern Europe and the Balkans, in Eurasian steppe in Ukraine, southern Russia into southern Siberia and northern Kazhakstan, and the Caucasus into Turkey.

Iris pumila is distinguished by single blooms held 10–20 cm above ground level on a lengthened perianth tube, with the ovary almost resting on the rhizome on a very short stem. The flower is protected by two spathes, both of which are round in cross-section. Flower color is variable: yellow and purple or violet are the most common, but blue, cream, white, and blended colors are also frequently found. Most forms have a darker spot on the falls.

Beginning in the mid 20th century, Iris pumila was bred extensively with the hybrid tall bearded irises of gardens, giving rise to the great variety of modern dwarf and median bearded iris cultivars.

Another pumila hybrid is 'Iris coerulea' named by Édouard Spach in Hist. Veg. Phan. xiii. 50 in 1846.