Seeds from Iris kaempferi. The Japanese Iris is a member of the Kaempferi genus. A hardy perennial, which has the largest flowers of any Iris and will flower in the summer. The Japanese Iris has sword shaped leaves and embellishes blue, white or purple flowers on top with 3 foot long stems. Will thrive next to a pond and is a very attractive addition to the water garden. Hardy in Zones 5-10.