Well, it seems there is much confused information on pulsatilla species! It could be patens, ambigua, multifida, nuttalliana, hirsutissima, ludoviciana, occidentalis or plain old vulgaris. Over to you..
I did take a film picture, so it needs to be developed. And of the flower too(not so unusual). I guess I erroneously thought that palmate leaf structure would be an easy identification. Of the species you listed, only vulgaris is on the list of seeds I planted. But everyone knows how infallible seed package labels are. Most came from NARGS. These are the species "possibilities," from the seed I planted:
halleri ssp. slavica
(and not that every species came up, mind you)
The flower was basically white, with some purple veination, and petals very rounded(to an oval shape). Flower upfacing. I do have a pic of it in bud:
It looks a very interesting flower with those brown hairs, from my amateurish eyes not like vulgaris which are the pulsatilla I have. I hope you do find out what it is. I see both are in pots. Are they indoors?
Pots stay outside all winter. These plants are getting planted in the ground . . . today, in fact. Also have turczaninovii blooming in a pot now. Can't wait 'til I post pics. Dare I say, it is true blue?