Annual honesty, a member of the mustard family, is native to the Balkans and naturalized throughout Europe, North America, and parts of Asia. It is a tall (about 1 m) hairy-stemmed biennial plant, which has large, pointed oval leaves with marked serrations.
Annual honesty flowers in April/May and is pollinated by bees, flies, moths and butterflies. The fragrant flowers, individually stalked, have 4 petals and are usually purple but may be white or parti-colored.
The green seedpods are large, circular and flattened and are firmly attached to the stem. During the ripening process they often take on a purple coloration, which is usually complete by early August. The outer cases and seeds then fall away, leaving the intermediate membranes still attached to the plants. The empty seedpods become papery and nearly white with age [see photograph] and are borne on the plant throughout the winter.
The empty, translucent seedpods look like ‘silver pennies’ and, therefore, annual honesty is also called ‘money plant’.