A fine genus of plants, grown for their spiky foliage and bracts, silvery blue, silvery green or just plain silver, with teasel-like heads of flowers, the shape and size of an egg, although in the same is a quail’s egg, and in other a duck’s. The plants include the sea hollies, and some spectacular ones with vicious spines. Many are monocarpic, but are easily propagated from seeds, and may seed themselves gently in the garden.

Eryngium amethystinum is a fine form of an excellent species, usually with silvery-blue flowers and finely divided violet-blue bracts, and toothed, spiky leaves, but in this case with a more purplish, amethyst colour.