Kerria

Kerria is a small genus of flowering plants in the family Rosaceae, primarily represented by Kerria japonica, commonly known as Japanese Kerria. The plant is native to East Asia, including China and Japan, and is widely cultivated as an ornamental shrub in temperate gardens around the world. The genus is often treated as monotypic, with K. japonica as its principal species.

Kerria japonica is a deciduous shrub that typically grows 1 to 3 meters tall, with a rounded, arching form. The leaves are alternate, oval to lanceolate, and finely toothed. In spring, the plant bears bright yellow flowers about 2 to 3 centimeters in diameter, usually with five petals; many cultivars produce blooms before or with the appearance of leaves. A notable cultivated form is Kerria japonica 'Pleniflora', which features fully double, pompon-like blossoms and a more showy display.

cultivation and care: Kerria prefers well-drained soil and a sunny to partially shaded site. It is relatively hardy in temperate climates and responds well to pruning after flowering, which helps maintain shape and encourages a vigorous bloom load in subsequent seasons. Propagation is commonly by softwood cuttings, layering, or division.

Pests and diseases: The plant is generally resistant to pests but can be susceptible to issues such as powdery mildew in damp conditions or aphid infestations in some regions.

Etymology: The genus name Kerria honors William Kerr, a 19th-century plant collector who introduced the shrub to European gardens. Kerria japonica remains the most widely grown species in horticulture.