Eryngium maritimum, also called the sea holly, sea eryngo, or sea eryngium, is a perennial species of flowering plant in the carrot family Apiaceae, native to the coasts of most of Europe and the Mediterranean. Alternatively, the name may have come from the Greek word "eruggarein", meaning to eructate (belch), since the plant was used to treat various digestive disorders such as trapped gases. The specific epithet maritimum means "of the sea".

The common English name appears to date from the 16th century. The naturalist William Turner stated In his 1548 publication The Names of Herbes that "Eryngium is named in englishe sea Hulver or sea Holly".

Description

thumb|Sea holly at a beach in [[Connacht, Ireland.]]

Sea holly is a bluish-grey, succulent, clumped perennial to 50+ cm, entirely hairless, with sizeable, wavy, stiff, spiny leaves. It is adapted to the dry (xerophytic) with a deep, well-developed root system and waxy leaf cuticle. The lowest leaves (5–15 cm, with. stalk) are rolled when young, and are palmately 3(5)-lobed with roundish outline and truncate or cordate base, The whorl of leaves under the heads (bracts) are spiny and leaf-like, and the small bracteoles among the flowers are 3-spined. The sepals, 4–5 mm, are longer than the petals.

and the flowers are attractive to butterflies.

The fruit, 13–15 mm, is more or less uncompressed and covered in stigmatic papillae which become longer towards the apex. The styles are about 6 mm long, divergent to somewhat recurved.

Identification

Apart from its specific coastal habitat in sand or sometimes shingle, sea holly is recognisable by the bluish-grey holly-like spiny leaves.

Hybrids

Although hybrids of E. maritimum have been reported, they are relatively few. For example, records have been made of a hybrid between E. maritimum and E. campestre (=Eryngium x rocheri Corb. ex Guétrot) in France, and in the region of Valencia, Spain.

Distribution

The species is found along the coasts of most of Europe and the Mediterranean.

In Great Britain, it is found along the coasts of England, Wales and Ireland, however, it has largely become rare to extinct from the coasts of northeast England and much of Scotland. Nevertheless, it may have once been more common and widespread there. It was formerly extant in Shetland, but it never properly established itself at the northernmost limit of its native range. The last documented occurrence in Shetland was at Fitful Head in 1884, where the plant is presumed to have been widespread on the sands of the Bay of Quendale.

In Europe and adjacent parts of northern Africa and the Middle East, the plant has a wide native distribution. In these regions, it occurs on the shores of the Atlantic Ocean, the Baltic and Mediterranean Seas as well as the Black and Azov Seas. The Scandinavian distribution is relatively southerly, extending only as far north as southern Norway and Sweden.

Sea holly has been introduced to parts of eastern North America, where it was once valued as an ornamental plant for coastal restoration. It has also been introduced to Australia with the planting of marram grass.

Habitat and ecology

Sea holly grows characteristically on the well-drained substrates of sand dunes and shingles, and is restricted to regions with mild winters. It withstands the harsh environmental conditions typical of beaches and coastal dune habitats worldwide; namely low soil nutrient levels, frost, strong salty winds, high temperatures and insolation, and periodic sand burial. On dunes, sea holly may be found growing in the Elymus farctus ssp. boreali-atlanticus foredune community, declining when habitats are invaded by shrubby species such as Rosa rugosa, Hippophae rhamnoides, Elaeagnus commutata and Salix repens due to substantial shading effects although it is protected against water stress through excessive insolation thanks to its succulent equifacial leaves.

Sea holly has deep, well-developed taproots for water storage, allowing the plant to survive long dry periods that may occur in its habitat. The root system also shows a high degree of plasticity in response to the dynamics of coastal ecosystems and may consequently develop a rhizome-like structure. For example, in response to permanent sand burial, the root internodes gradually lengthen in such a way that the perennating buds are brought closer to the ground surface for ensuring the plants' survival throughout the growing seasons.

thumb|A sea holly plant on a sandy beach, uprooted by a storm.

Status

Despite a widespread native European distribution, populations of this species have declined significantly in the northern parts of its range, with some of these already having become extinct. It is now threatened or endangered in most European countries and included in endangered plant lists and Red Data Books of several of these countries In Britain, its historic decline may be at least partly attributable to being dug up from the wild on account of its popularity as an ornamental plant in gardens on dry soils.

In culture, use and relationship with humans

Like other species in the genus, E. maritimum has been traditionally consumed to combat various ailments, especially thanks to the plant's high antioxidant activity and content of phenolic and flavonoid compounds. It has been utilised for its diuretic, stimulant, cytotonic, stone inhibitor, aphrodisiac, expectorant and anthelmintic properties. Moreover, essential oils, extracted by hydro-distillation, from the aerial parts of the plant have been found to contain oxygenated sesquiterpenes with antimicrobial activity against E. coli and L. monocytogenes.

The roots of E. maritimum were formerly candied as a sweetmeat and recommended by Dioscorides as a remedy for flatulence. The young shoots may also be eaten like asparagus. and the 25-pfennig stamp in Germany and in the Italian Journey by Goethe.

They are named in a speech by Falstaff:

Sea holly was nominated the 2002 County flower for the city of Liverpool. Asteroid 199194 Calcatreppola was named after this plant.

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  • Plants for a Future—PFAF Plant Database: Eryngium maritimum (Sea Holly)
  • Schutzstation-wattenmeer.de: Further information and images—
  • Linnaeus.nrm.se; Den virtuelle floran: Distribution map