Cosmos atrosanguineus

Native to Mexico, where it is now nearly extinct in the wild, Cosmos atrosanguineus is a tuberous perennial in the Asteraceae family, grown for its flowers. The fleshy roots produce dark green, cut foliage and stems bearing, from summer into autumn, velvety, very dark maroon to almost black flower heads with a characteristic chocolate scent. It requires a sunny position, fertile, well-drained soil, and winter protection — mulching or lifting the tubers — in climates with cold, wet winters.