Plant 352

Romneya coulteri Harv. (Papaveraceae)

Matilija poppy

The Matilija poppy, a shrubby perennial with a creeping rootstock, has the distinction of possessing the largest flowers of almost any native Californian plant. Each flower, which is about twenty centimetres in diameter, has six white, wrinkled petals that contrasts with a halo of many, golden-yellow stamens. Moreover, individual plants may reach over two metres in height. As a garden plant it was introduced into Britain in about 1875 but requires a warm site in full sun to flourish. One enthusiast stated: ‘it must be conceded the queen of flowers’ but warned that Romneya was ‘not a plant for small gardens, but the fitting adornment of a park where it can have space, and light, and air’. Within its native range, the Native American Cahuilla people of southern California are reported to use sap from the stem of Romneya coulteri as a beverage.

In 1845, the Irish botanist William Henry Harvey (1811-1866), Director of the Glasnevin Botanic Garden, named the genus after his friend the Irish astronomer and Anglican priest John Thomas Romney Robinson (1792-1882), Director of the Armagh Astronomical Observatory. The specific name, coulteri, commemorates the Irish botanist and traveller Thomas Coulter (1793-1843), Harvey’s immediate predecessor as Curator of the Herbarium at Trinity College, Dublin. Moreover, in 1832, Coulter had collected the type – the specimen Harvey used to formally describe the species – in northern California, during his decade-long period of botanical exploration in Mexico and California from 1824 to 1834.

In 1898, based on plants cultivated in a park in San Francisco, the North American botanist Alice Eastwood (1859-1953) showed there were two species of Romneya in cultivation. The new species, Romneya trichocalyx, was most obviously separated from Romneya coulteri by having bristles on the outside of its calyx. In natural populations of a species, presence or absence of hairs is sometimes associated with the conditions in which plants are growing. For Eastwood to be convinced that plants with hairy and smooth calyces were different species, it was essential that she study them growing under a set of common environmental conditions.

Both species occur naturally in dry, Californian desert canyons, where there is no permanent supply of water but where there are periodic floods, whilst the distribution of Romneya trichocalyx extends into northwest Mexico. The two species apparently hybridise in cultivation, consequently some botanists prefer to recognise only Romneya coulteri, with two different varieties, var. coulteri and var. trichocalyx.

Further reading

Hemsley, WB 1905. Romneya trichocalyx. Curtis’s Botanical Magazine 131: t.8002.

Meikle RD 1974. Romneya coulteri Papaveraceae. Curtis’s Botanical Magazine 180: 83-87.

Stephen Harris