Liatris commonly called Blazing-star, Gay-feather or Button snakeroot is a genus of ornamental plants in the Eupatorieae tribe of the Asteraceae family, native to North America.
Liatris spicata A widely cultivated herbaceous hardy perennial, typically available in white and purple. Tubers bought in winter will flower in late summer. An unusual feature is that the flowers open from the top of the flower spike downwards. Although a member of Asteraceae, the flowers are not classic daisies as they have no ray florets. However, comparing photos 5 and 6 with those of the details of a more daisy like flower such as Dahlia reveals that what might appear to be wispy petals are extra large styles. Pictures by David Pilling.
Photo 1 shows bulbs as bought from a supermarket in early April; the coin is around 1 inch in diameter. Photo 2 confirms the description given at EOL: "The leaves are linear in shape and their margins are smooth (entire). Each leaf has a distinct central vein. Both the upper and lower leaf surfaces are light to medium green and glabrous to sparsely hairy." Photos 3 and 4 show the details of an individual floret. Photos 5 and 6 are of ripening seed.