Eryngium, commonly known as sea holly, is a genus of herbaceous perennials valued for their striking, architectural form and spiny, metallic-toned flowers. Plants typically form basal rosettes of leathery, often toothed or spiny leaves, with upright stems bearing cone-shaped flower heads surrounded by star-like bracts in shades of steel blue, silver, or occasionally green or purple, appearing from summer into early autumn. Most species are deciduous, dying back in winter. It is commonly used in borders, gravel gardens, and naturalistic plantings for its bold texture and long-lasting colour and is also popular for cut and dried flower arrangements.