I grew this plant from seed labeled Trollius laxus, but once it flowered it was clear that there had been some mix-up. It's identity has long been a mistery to me and I've searched the web far and wide. I'm not 100% sure I've correctly identified it, but it does resemble T. riederianus quite a bit. It's native to NE-Asia, E-Russia and Japan, It starts flowering very early, even in late April and flowers into June. Like other species of this genus it prefers moist, humus-rich soil in a sunny position.