10-15 cms. An Iris of North American origin, preferring to grow in part-shade in moisture-retentive but well-drained soil, preferably acid. From a mat of rhizomatous roots rise light green lanceolate leaves, followed in May by wiry stems bearing 1-3 showy flowers, mauve-blue with a central white stripe, which sports a golden yellow stripe in the middle. It grows vigourously when well-suited. Beware slugs!