By this, the boy who by her side lay kill'd
Was melted like a vapour from her sight,
And in his blood that on the ground lay spill'd,
A purple flower sprung up, chequer'd with white,
Resembling well his pale cheeks and the blood
Which in round drops upon their whiteness stood.
Venus and Adonis
For an unlikely if nevertheless alluring connection between Shakespeare and the Snake's-head Fritillary, follow this link here.