noun
Botanical term for a plant that lives for more than two years, regrowing each spring from the same root system.
宿根草は毎年花を咲かせます。
Perennial plants bloom every year.
多年草 is a broader term for any perennial plant; 宿根草 specifically emphasizes overwintering via persistent underground parts.
Compound of 宿 (しゅく, 'lodging, staying') + 根 (こん, 'root') + 草 (そう, 'grass, plant'), referring to a plant whose roots persist through winter.