It is an annual or biennial growing to 90 cm (35 in) tall by 30 cm (12 in) broad, with large, coarse, pointed oval leaves with marked serrations. The leaves are hairy, the lower ones long-stalked, the upper ones stalkless. In spring and summer it bears terminal racemes of white or violet flowers, followed by showy, green through light brown, translucent, disc-shaped silicles (not true botanical seedpods). When a silicle is ripe and dry, a valve on each of its sides readily falls off, and its seeds fall off a central membrane which has a silvery sheen, 3–8 cm (1–3 in) in diameter; the membrane can persist on a plant throughout a winter depending on the weather. These silicles are much used in dry floral arrangements.
The Latin name lunaria means "moon-shaped" and refers to the shape and appearance of this species' silicles. The common name "honesty" arose in the 16th century, and may also relate to the translucence of its silicle membranes. In South East Asia, it is called the "money plant" and in the United States it is commonly known as "silver dollars", "Chinese money", or "Chinese coins" because its silicle membranes have the appearance of silvery coins. For the same reason, in French it is known as monnaie du pape ("Pope's money"). In Denmark it is known as judaspenge and in Dutch-speaking countries as judaspenning (both meaning "coins of Judas"), an allusion to the story of Judas Iscariot and the thirty pieces of silver he was paid for betraying Christ.
In the language of flowers, the plant represents honesty, money, and sincerity. In witchcraft, the honesty plant is considered protective, being thought to keep away monsters. The plant is also used in spells for prosperity, the flat pods (when ripe and silvery) resembling coins and therefore being seen as symbolising promises of wealth. In the earliest surviving recipe for a flying ointment (recorded by Bavarian physician Johannes Hartlieb circa 1440), Lunaria is included as the herbal ingredient corresponding astrologically to the moon and therefore to be picked on the lunar day of Monday.
This plant is easy to grow from seed and tends to naturalize. It is usually grown as a biennial, being sown one year to flower the next. It is suitable for cultivation in a shady or dappled area, or in a wildflower garden, and the flowers and dried silicles are often seen in flower arrangements. Numerous varieties and cultivars are available, of which the white-flowered L. annua var. albiflora and the variegated white L. alba var. albiflora 'Alba Variegata' have won the Royal Horticultural Society's Award of Garden Merit.
- Dame's violet, Hesperis matronalis, a similar and related plant, but with long cylindrical seedpods instead of flat papery disks.
- Lunaria rediviva (perennial honesty)
- Pilea peperomioides, another plant known colloquially as the Chinese money plant.
- "Lunaria annua L." Plants of the World Online. Board of Trustees of the Royal Botanic Gardens, Kew. 2017. Retrieved 23 November 2020.
- Parnell, J. and Curtis, T. 2012 Webb's An Irish Flora. Cork University Press ISBN 978-185918-4783
- RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 978-1405332965.
- Coombes, Allen J. (2012). The A to Z of plant names. USA: Timber Press. pp. 312. ISBN 9781604691962.
- "Judaspenning", Van Dale's Groot woordenboek van de Nederlandse taal, online edition, retrieved 23 May 2020
- Hartlieb, Johannes, das puch aller verpoten kunst, ungelaubens und der zaubrey, 1450s, CPG 478, 78 foll. (in the hand of Clara Hätzlerin), 1465, ed. Eisermann and Graf (1989).
- "RHS Plant Selector - Lunaria annua var. albiflora". Retrieved 29 October 2020.
- "RHS Plantfinder - Lunaria alba var. albiflora 'Alba Variegata'". Retrieved 25 March 2018.
- "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 62. Retrieved 25 March 2018.
- "Money Plant (Lunaria annua)". www.illinoiswildflowers.info.