Paeonia mairei, probably somewhat ahead of itself. This is the first flower I've seen of this species. Opened yesterday.
This plant is grown from seed collected from plants in cultivation, so it may or may not be true to the species. Certainly the foliage is unique amongst all my peonies, and consistent in the three plants which resulted from that seed batch. Two are now in flower and the flowers are also consistent with each other.
The leafs of my plants remain very dark red for quite awhile after they have almost fully deployed, and then turn a dark shiny green with a notable veining texture. The leaflets are narrow and sharply pointed.
P. mairei, named after French botanist RCJE Maire, is native to central China (Yunnan and Sichuan provinces) where it grows in open woodlands and along riverbanks, at altitudes ranging from 800 to 3500m (JJ Halda, "The Genus Paeonia"). It's closely related to Paeonia obovata, although I don't see much commonality between the two in my plants here. It is said to be tolerant of shade and damp soils.
I expect the first flower of Paeonia tomentosa to open tomorrow (while I am out on the bike)-- we are having a short stretch of summery weather for a change, and the previously stalled plants are taking advantage of it. As are the previously stalled cyclists (this one anyways).