According to Wikipedia, “eranthis (winter aconite) is a genus of eight species of flowering plants in the buttercup family, Ranunculaceae, native to southern Europe and east across Asia to Japan.” E. hyemalis is the one from France and Italy and the one that is most commonly grown, while E. cilicica is similar (and is sometimes listed as a subspecies of E. hyemalis); it hails from southwest Asia. Both have yellow flowers with deeply dissected foliage that opens fully after the flowers have finished. But the jewel in the crown is the Japanese species, E. pinnatifida.
This is a miniature plant growing from a miniature tuber. It is so small it would soon be lost in the hurly-burly of the garden, so growing it in a pot or small trough is the best way to safeguard it. E. pinnatifida is a woodland plant, requiring a peaty, humus-rich soil and a position in light shade. Nurseryman Paul Christian notes “it is not as easy, nor as tolerant, as the European Eranthis and it is not a plant that you can ….. expect to see clumps of.” It is very slow to increase by eiher seed or offsets, so don’t expect carpets of them (wouldn’t that be nce?), just one or two. But then the most sought-after jewels are enhanced by their rarity, and this is definitely one to acquire and cherish.