Kerria japonica, also known as Japanese Kerria or Japanese Rose, is a stunning deciduous shrub in the rose family Rosaceae. It is the sole species in the genus Kerria and is native to China, Japan, and Korea. The plant was named after William Kerr, who introduced the popular cultivar 'Pleniflora'. In fact, the scientific genus name is also commonly used as a name for the plant itself.
This beautiful shrub can grow to be 1-3 meters tall, with weak arching stems that often scramble over other vegetation or rocks. It thrives in thickets on mountain slopes in its native environments. The leaves are bright green and simple, with a serrated margin that adds to its visual appeal. In the spring, the plant produces lovely golden yellow flowers that are evenly spaced along the branches of new green growth. These flowers add a vibrant burst of color to any garden.
Kerria japonica is highly valued in gardens for its striking and abundant flowers. It is best grown with some shade from full sunlight to avoid blanching the flowers. After flowering, it is important to prune the plant to maintain its health and vigor. Two cultivars of Kerria japonica, 'Golden guinea' and 'Pleniflora' (commonly known as bachelor's buttons), have gained the prestigious Royal Horticultural Society's Award of Garden Merit.
Although it is a beautiful and popular garden shrub, Kerria japonica is susceptible to certain pests and diseases. In recent years, gardeners and horticulturalists in the UK have reported damage to the shrub caused by the fungus Blumeriella kerriae. This disease, known as kerria twig and leaf blight, can result in defoliation and even death of the plant. It is considered a serious threat to cultivated Kerria japonica plants in gardens.
Aside from its ornamental value, Kerria japonica also has medicinal uses. A decoction of the flowering shoots is used in the treatment of coughs and women's complaints.
Overall, Kerria japonica is a stunning and versatile shrub that adds beauty and color to any garden. With proper care and attention, it can thrive and become a focal point in your outdoor space.
