Ajuga japonica

About

Ajuga japonica is a herbaceous flowering plant native to Japan. The species grows as a groundcover on the forest floor, usually near streams. It is often found in large clusters, due to its spreading and seeding habit. It grows along the ground by stolons, and is usually 8–20 cm (3–8 in) high, including the flowers. It flowers between late April and late May.

Summary from Wikipedia