By the Middle Ages, Sun Spurge was already to be found in herbariums under the name E. helioscopia, although the Latin word helioscopia, meaning to follow the sun, is something of a misnomer in that the flowers of this plant do not actually follow the sun’s path in the sky.

Cyanus, the botanical name designating the species, recalls the nymph Cyane, daughter of the river god Meiandros: she was changed into a dark blue spring whose waters fed the small brook Anapis near Syracuse.

Now a cosmopolitan plant, Thornapple is one of twenty-five species of the genus Datura native mostly to the tropics. It was carried to the west largely by nomadic tribes. In the late sixteenth century it was introduced into Innsbruck and Vienna, and here in Central Europe soon became established in the wild. It was, of course, used as a hallucinogenic drug: seeds placed on hot coals caused intoxication in people inhaling the smoke, and this fact’ is reflected in the name by which the plant is still known in some parts of France – Herbe aux sorciers.

In Arab countries, Thornapple was added to drinks and tobacco to produce similar euphoric effects. Today, it remains an effective ingredient in anti-asthmatic preparations.

The Cornflower is an overwintering herb multiplying only by way of its seeds. The arrangement of the flowerheads is a biological flower. The marginal ligulate florets are sterile, lacking both stamens and pistils, and serve to attract insects. The central florets are fertile. The flowerheads are firmly anchored in an involuere composed of stiff bracts with membranous margins. The filaments of the stamens in the tubular florets which form the central disc react to mechanical stimuli and contract immediately when an insect alights. This movement aids in pollinating the flowers. The flowering period is from June till autumn.

The seeds have a fleshy outgrowth which is a favourite food of ants and this is a factor contributing to the plant’s dispersal. Unlike Sun Spurge, Dwarf Spurge (E. exiqua L.) has small linear leaves.