Thalictrum filamentosum(Meadow rue)

Thalictrum filamentosum is a herbaceous perennial flowering plant in the Ranunculaceae (buttercup) family distributed in Russia, China, Japan and Korea.
The white flowers are small and apetalous (no petals), but have numerous long stamens, often brightly white, looks like petal, and are produced in conspicuous dense inflorescences.