They are large rhizomatous herbaceous perennials with palmately lobed, frilly leaves of olive green or grey colour, 25 cm (10 in) long, and tall stems with airy plumes of petal-less, tubular, off-white or cream flowers.

[3] Macleaya is named after the Scottish entomologist Alexander Macleay (1767-1848).

The individual flowers are insignificant, but the combined effect of multiple stems four to six feet high can give a striking architectural effect.

They spread both by underground suckers and by seeding, so can be difficult to get rid of in some situations.

The cultivar M. × kewensis 'Flamingo' has gained the Royal Horticultural Society's Award of Garden Merit.