Lunaria annua originates in Central and Southern Europe but has spread far beyond its native range and is now naturalised across many temperate regions. It is a biennial, germinating in spring and remaining vegetative during the first year, flowering the following spring in April and May. It favours dappled shade and can often be seen growing on the edges of woodland, maintaining a foothold by self seeding profusely. It was recorded in the 1648 Oxford Botanic Garden catalogue, and the botanist John Gerard included it in his famous Herbal of 1597, noting it growing 'wilde in the woods about Pinner and Harrow on the Hill, twelve miles from London'.
It is an erect herb with broad, coarsely toothed, heart-shaped leaves rising up a tall stem. The small cruciform flowers grow on slender branches and are purple or white with four, small petals characteristic of plants in the family Brassicaceae. The flowers have a sweet floral scent and attract long-tongued bees and butterflies that can reach its nectar. As with many brassicas, Lunaria is a food source for the voracious caterpillars of the cabbage white butterfly. The genus Lunaria contains only four species, the other three being the rare Lunaria telekiana, endemic to the Prokletije Mountains in the Balkans, Lunaria elongata and the perennial Lunaria redivivia.
In modern times, Lunaria has been grown as an ornamental for its spring flowers and the decorative value of the seeds pods but research is being undertaken into its potential economic value. The oil extracted from the seed has been studied for its medicinal and cosmetic uses, and as a component in the production of biodiesel. However, the biennial nature of Lunaria has so far proved uneconomic for commercial production.
Most striking in its dried form, the Lunaria's skeletal appearance is most eye-catching in the winter garden. Lunaria's common and botanical names do not refer to the flower but the oval seed pods and the shimmering silique that remains once the pod splits to drop the seed. The generic name Lunaria, meaning moon-shaped, refers to appearance of the flattened round seed cases. There are plenty of common names, many referring to money such as money plant, moneywort, penny flower, silver dollar and money-in-both-pockets. It is known as Honesty owing to the 'truthfullness' of the translucent pod revealing the seeds beneath, and also as pricksong-flower, the siliques resembling the notes of Elizabethan musical manuscripts, called pricksongs.
Leins P et al. 2017. Silique valves as sails in anemochory of Lunaria (Brassicaceae). Plant Biology 20: 238-243.
Mastebroek HD and Marvin HJP 2000. Breeding prospects of Lunaria annua L. Industrial Crops and Products 11: 139-143.