A well-grown Eryngium, with its spiny foliage and branching heads of teasel-like, long-lasting flowers, usually of a bluish almost metallic tinge, stands out well in any border. The genus contains around 250 species. They are all highly decorative, and make fabulous garden plants. Eryngiums are striking, highly distinctive hardy perennial plants. Each summer, eryngiums produce a number of flower heads—moreso with older plants—and these heads comprise a central egg-shaped cone of many small flowers, usually in shades of blue and pale violet. This cone is supported by a ring, or ruff, of bracts, which have the appearance of being spiny and spiky, but are actually soft to the touch (they evolved to discourage grazing animals).

With common names including sea holly and blue eryngo or just eryngo, these architecturally interesting and long-lasting plants are unfussy as to soil type, providing it drains well. They prefer a position in full sun, but will grow perfectly well in part shade. Some taller types will benefit from staking, especially if your garden is exposed.