Pulsatilla vulgaris alba

Check out the matching stigmas and petals. Wonderful in flower and in seed. 

The popular pasque flower has large white flowers. Lovely divided foliage, with superb seed heads following large bell flowers. Easy to establish in the garden from borders to containers and rock gardens, seeds happily and will come true if colours are separated. Good drainage and sun is needed. Surprisingly tolerant of drought.  Hardy. 30-50cm H when in seed.

Seedlings from any particular seed lot will likely be a mixed bunch. Size and vigour, leaf division and hairiness, as well as flower colour, are all likely to vary. Various shades of pink, red and purple are likely, so if you are choosy it is best to buy plants in flower. If you want to breed true... pollinate yourself or keep with the right sort of parents.

In this case you are getting a flowering one.

The reason for this variability is that our native pasque flower has been in cultivation for centuries, allowing many forms and variants to be selected. Also, P. vulgaris. crosses readily with closely related species commonly grown in gardens, notably P. grandis and P. halleri.

Top left red, top middle, 'Denim Pink', top right, white. Lower left purple, inset mauve (not quite enough light). Sizes are not important, It depends on the health and age of the plant. A sunny garden is best.