noun
pipewort (Eriocaulon cinereum)
A small aquatic or marsh plant with tiny star-like flower heads. The name 星草 literally means 'star grass'.
水田のあぜに星草が咲いていた。
Pipewort was blooming on the ridge between the rice paddies.
Compound of 星 (hoshi, 'star') and 草 (kusa, 'grass'), referring to the plant's star-shaped flower heads.