Rhizome wiry. Leaves flat, sword-shaped, 40-65 cm long. Stems to 80 cm, 2-3 branched. Spathes 4-8 cm, green. Flowers 2-3, purple to lavender, 8-9 cm wide; summer. Perianth tube 7-10 mm long; falls oblanceolate, 6-7 cm long, with green signal surrounded by white zone; standards erect, oblanceolate, 3 cm long. Style branches 6 cm long, violet.

NE USA.

I. virginica L., Southern Blue Flag from SE USA has flat leaves 1-3 cm wide. Stem to 100 cm, usually unbranched, arching. Flowers 2-4, blue, violet, lavender or white, 6-8 cm wide Falls lanceolate, with yellow signals. Standards erect, longer and narrower than falls. Late spring. Var. shrevei (Small) E. Anderson may be encountered. Cultivars include: 'Contraband Girl', 'Giant Blue', 'Latan Titan' and 'Native Wine'.

There are a number of natural hybrids between I. versicolor and I. virginica. 'Gerald Darby' is popular and attractive with mauve flowers, black stems and purple staining at the base of the leaf fans. 'Dark Aura' has purple new leaves in spring later reverting to green. Raised J. Hewitt, UK, 1990s.

Source: Cooke, D. (2005). Iridaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.