Iris sibirica, the Siberian Iris, is a flowering plant in the genus Iris, native to eastern and central Europe and northern Asia.
It is a herbaceous perennial plant growing to 50-120 cm tall. The leaves are glaucous green, narrow and fairly rigid, blade-shaped, 40-80 cm long and 2-4 cm broad. The flowers are typical of an iris, borne in late spring or early summer on unbranched or sparsely-branched stems held above the leaves, each flower 4-7 cm diameter, mid- to purple-blue, often with a paler whitish or yellowish centre.
Description taken from Wikipedia: http://en.wikipedia.org/wiki/Iris_sibirica