Sea holly

Sea holly, botanic name Eryngium maritimum, is a perennial plant, native to Europe, and often found on sea shores. It produces a basal rosette, from which grow flowering spikes with stiffly spiny foliage and stems. These can reach around 50 cm in height.

It is often grown in gardens for its metallic bluish flowers and upper foliage. The basal foliage is a grey or silvery green. For garden use however, it is often passed over in favour of its more strongly coloured and more ornamental relatives.

The roots have been used as vegetables or for sweetmeats. They are also considered to have a number of herbal uses, including aphrodisiac qualities. Young shoots and leaves are sometimes used as an asparagus substitute.

Related species are used in the garden, and these may also be called 'sea holly', though the majority are not associated with littoral (sea-shore) habitats. Among the best known of these is Eryngium bourgatii (illustrated), a perennial with stunning green, prickly foliage marbled with silver. The flowers, which appear in summer, are cobalt blue, and very attractive to bees. The plant is 30 to 60 cm in height. Other commonly grown ornamental species include Eryngium alpinum, E. variifolium, E. tripartitum, E. bromelifolium, and the biennial E. giganteum.