Romneya is a genus of flowering plants in poppy family Papaveraceae, containing only two species, Romneya coulteri and Romneya trichocalyx. It is commonly known as Matilija Poppy, Tree poppy or California poppy. Romneya is native to southern California and northern Mexico.
Romneya is a perennial subshrub with a woody stem, growing to 2.5 m tall and 1 m wide, with silvery green leaves that are deeply cut, with a small fringe of hair at the margin. Romneya is known for its large, white, fragrant summer flowers with intense yellow centers, which can grow to 13 cm across.
Romneya coulteri (Coulter's Matilija poppy) has lobed, grey-green leaves and flowers that lasts from midsummer to early autumn. The flowers have papery white petals with brilliant yellow stamens, and they are followed by seedpods.
Romneya plants are not easily grown, but when they are growing strongly, they can produce suckers and become invasive, and difficult to remove. They do best against a sunny wall, protected from blustery winds, in fertile and well-drained soil. Propagation is through seed in spring or by root cuttings in winter.