Argemone platyceras - Prickly Poppy

The Argemone platyceras, sometimes called "thistle poppy," is a short-lived plant related to poppies that is quite attractive. Its large white flowers with a red centre and golden stamens bloom during a long spring to summer period, on ramified spikes that emerge from a thistle-like foliage. Native to the northern regions of Mexico and the southwestern United States, this curious poppy thrives in the sun and dry, poor soils where it naturalises quite easily.

The Argemone platyceras is an annual to biennial herbaceous plant, or even a short-lived perennial, classified in the family Papaveraceae. This botanical species is found in subtropical America, from Arizona and New Mexico to northern Mexico, between 450 and 2500 metres (1476 and 8202 feet) above sea level. Its natural habitat consists of rocky areas, slopes, fallow lands, and cultivated fields. Hardy down to -10 °C (14°F), this plant is perfectly adapted to fairly arid climates and poor, dry soils.

With rapid growth, this argemone reaches about 50-60 cm (20-24in) in height and 40-50 cm (16-20in) in width when flowering in just a few months. The plant, with a taproot, forms a rosette of basal leaves from which spiny leafy stems emerge. The leaves can measure up to 30 cm (12in) long and 13 cm (5in) wide. Those located towards the base of the plant are pinnate and deeply lobed with spiny edges. Their colour is a bluish grey-green. Flowering occurs between April and October, with a duration of three months. It will be earlier in warm and dry climates. The flowers are cups measuring 10 to 15 cm (4 to 6in) in diameter, carried at the ends of ramified spikes. The centre of the corollas, reddish in colour, is occupied by a beautiful bouquet of yellow stamens. After pollination by insects, the flowers give way to fruits that are ellipsoidal ovoid capsules measuring 2.5 to 4.5 cm (1 to 2in) long. They contain a large number of seeds that will be dispersed by the wind. These seeds easily germinate in sunny, well-drained soils.

The Argemone platyceras is ideal in a dry garden without watering, where it perpetuates itself through self-sowing. It is an excellent plant for dry rock gardens or gravel beds, also well-suited for coastal gardens. This short-lived plant, like love-in-a-mist and other poppies, is perfect for filling in unsightly embankments around new constructions. It forms beautiful, very floriferous clumps among lavenders, rockroses, and rosemary. It can be directly sown in open ground.