Kerria japonica - Japanese Kerria Family: Rosaceae (Ker-ria: named for William Kerr, Kew Gardener and Collector) Kerria japonica is a hardy (Zone 5) deciduous shrub that matures at 3 to 5 feet in height. Its a dense mounded plant with numerous slender, zigzagging branches that emerge at ground level. The beauty of Kerria is found in its flowers, stems and foliage. The bright yellow flowers are noticeably reminiscent of an old fashioned rose with its 5 petals. The flowers clearly make this plant ...