Glaucidium palmatum, a monotypic genus from northern and eastern Japan; it is, of course, in the Rannunculaceae family (all my favorites are!) This tiny woodland gem came to my garden as one sprout and one leaf. After two or three years it has survived (not prospered) through the cold winters, warm summers, periods of drought and flood, and this spring it put up its first bloom. And what a bloom it is. This solitary flower has been showing off for over a week, through heavy rains and heavy frosts.
I recently wrote a short piece for the Garden Diary on the Great Dixter website. You can see it here.