Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Brassicales
Family: Brassicaceae
Genus: Lunaria
Species: L. annua
Binomial name: Lunaria annua
Common names: Honesty, Annual honesty, Money Plant, Coins of Judas

Lunaria annua is a species of flowering plant native to the Balkans and south-west Asia and naturalized throughout the temperate world. In New Zealand, it is garden escapee found on waste ground, railway cuttings and roadside verges.
It is an annual or biennial growing to 90 cm tall by 30 cm broad, with large, coarse, pointed oval leaves with toothed edges. In spring and summer it bears terminal racemes of pink, purple or white flowers with four petals, followed by showy, light brown, translucent, disc-shaped seedpods (silicles) the skin of which falls off to release the seeds, revealing a central membrane which is white with a silvery sheen, 3–8 cm in diameter; they persist on the plant through winter. These pods are much used in floral arrangements.

1- Lunaria annua plant.jpg

The four-petalled flower.
1-Lunaria annua closeup.jpg

The seed pods containing seeds.
1-Lunaria annua seed pods.mdldm.jpg

The translucent and papery seed pods hang on the skeleton of the plant throughout the winter. The name Honesty likely arose from the see-through nature of the pods.1-Lunaria annua, without seeds.jpg

Thanks to Wikipedia for text and information:

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