A hybrid fritillary

This is a hybrid between the purple and white forms of the snake's head fritillary Fritillaria meleagris, a lily native to Britain, once common but now quite rare in the wild. I planted a dozen bulbs in the garden some 10 years ago. They have proliferated wonderfully and we now have over a hundred in the patch. 

The name fritillary comes from the Latin fritillus meaning a dice-box. Back in 1597 J. Gerard wrote in his herbal that "It hath been called Frittillaria, of the table or boord vpon which men plaie at chesse, which square checkers the flower doth very much resemble, some thinking that the chess-board was named Frittillus." The chess-board pattern is best seen in the normal colour form.

The flower has several other common names including simply snake's head (the original English name), chess flower, frog-cup, guinea-hen flower, leper lily (because its shape resembled the bell once carried by lepers), Lazarus bell, and checkered lily.