Lunaria annua L. (syn.: L. biennis Moench) (SE-Eur.) – A rather frequent escape from cultivation that is locally naturalized (although long considered to be a merely ephemeral alien). First reported as an escape along hedges in Ayeneux in 1862 (repeatedly seen although only very rarely cultivated at that time, according to the herbarium label). Furthermore known from numerous, very widely scattered locations, often in abundance and obviously locally naturalized. Still regularly cultivated (but surely less so than it used to be) and in the past decades much increasing. At present regularly seen in Flanders (but still rare in Limburg; see Verloove 2006) and probably also less frequent in Wallonia (where, however, confusion is more likely with native Lunaria rediviva). Lunaria annua usually grows in shady, nitrophilous, often somewhat damp habitats: wood margins, shady road verges, as a weed in plantations, canal banks, old walls, etc.
References:
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Verloove F. (2006) Lunaria annua. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de flora van Vlaanderen en het Brussels gewest. Instituut voor Natuur- en Bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 558.