noun
A plant that lives for more than two years, typically flowering and producing seeds multiple times over its lifespan.
この庭には多年草がたくさん植えられている。
Many perennial plants are planted in this garden.
Compound of 多年 (tanen, 'many years') + 草 (sō, 'grass, herb'). The term is a straightforward Sino-Japanese botanical classification.