also: くされだま
noun
yellow loosestrife
A flowering plant (Lysimachia vulgaris) with yellow flowers, native to Eurasia. The Japanese name literally means 'rotten ball' or 'rotting jewel', possibly from the appearance of the flowers.
湿地にクサレダマが群生していた。
Yellow loosestrife was growing in clusters in the marsh.
The name クサレダマ is thought to derive from 腐れ玉 (くされだま, 'rotten ball') or 腐れ珠, possibly referring to the appearance of the flowers or seed pods. The exact origin is uncertain.