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. Its prickly holly-like leaves and compact flower heads give it the appearance of a thistle. Despite its common name, it is not a holly but an umbellifer.
Etymology E. maritimum was formally described by Linnaeus in his Species Plantarum I: 233 (1753).
Eryngium, the genus name, may have arisen from a description of the plant by the Ancient Greek Theophrastus (c. 300 BC), who referred to it as "Eryngion", meaning a spiny plant.Blindow I. 2006. Pflanze des Monats: Die Stranddistel. Inselnachrichten August, pp. 17–18. Hiddensee. 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.Huxley A, Taylor W. 1989. Flowers of Greece and the Aegean. Hogarth Press, London, UK. The specific epithet maritimum means "of the sea".Jaeger EC. 1959. A Source Book of Biological Names and Terms. Springfield, Ill: Thomas.
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".Grigson G. 1974. A Dictionary of English Plant Names. Allen Lane. pg. 192
Description
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,Poland J, Clement EJ. 2009. The Vegetative Key to the British Flora. Botanical Society of Britain and Ireland. and are palmately 3(5)-lobed with roundish outline and truncate or cordate base, thick margins, often with purplish veins, and stomata on both sides. The stem leaves are similar but smaller and stalkless. The stalks are channelled and dilated at the base. The cotyledons abruptly contract into a petiole.
The flowers are bluish white, 8 mm across, in 1.5–2.5 cm headsStreeter D, Hart-Davies C, Hardcastle A, Cole F, Harper H. 2006. Collins Wildflower Guide. Harper Collins. 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.
It flowers June to September, 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.
Its chromosome number is 2n = 16.Tutin TG. 1980. Umbellifers of the British Isles. Botanical Society of the British Isles Handbook No. 2, London. .
Identification
Apart from its specific coastal habitat in sand or sometimes shingle, sea holly is recognisable by the bluish-grey holly-like spiny leaves.Stace CA. 1991. New Flora of the British Isles. St Edmundsbury Press Ltd.
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,Stace CA. 1975. Hybridization and the Flora of the British Isles. Academic Press, London, UK.Wörz A. 1999. A taxonomic index of the species of Eryngium L. (Apiaceae: Saniculoideae). Stuttgarter Beiträge zur Naturkunde. Serie A (Biologie), 5. and in the region of Valencia, Spain.Aparicio Rojo JM. 2002. Aportaciones a la flora de la comunidad Valenciana, I. Flora Montiberica 22: 48–74.
Distribution The species is found along the coasts of most of Europe and the Mediterranean.
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.Isermann M, Rooney P. 2014. Biological Flora of the British Isles: Eryngium maritimum. Journal of Ecology 102: 789 – 821. 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.Scott W, Palmer RC. 1987. The Flowering Plants and Ferns of the Shetland Islands. The Shetland Times Limited.
In Europe and adjacent parts of northern Africa and the Middle East, the plant has a wide native distribution.Hegi G. 1975. Illustrierte Flora von Mitteleuropa. V.2, Parey, Berlin, GermanyHultén E, Fries M. 1986. Atlas of North European Vascular Plants (North of the Tropic of Cancer). Koeltz Scientific Books, Königstein, GermanyFitter AH, Peat HJ. 1994. The ecological flora database. Journal of Ecology 82: 415 – 42 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 distribution also extends northwards into Denmark, Germany, Poland, Lithuania, Latvia, and Estonia, along the Skagerrak and the Swedish islands of Gotland and Öland.Fröman, I. 1930. Phyllitis, Helichrysum och Eryngium på Gotland. Botaniska Notiser 1930: 225 – 232 The Scandinavian distribution is relatively southerly, extending only as far north as southern Norway and Sweden.Fremstad E, Moen A. 2001. Truete vegetasjonstyper i Norge, pp. 1–231. Norges teknisk-naturvitenskapelige universitet, Vitenskapsmuseet, Trondheim, Norway
Sea holly has been introduced to parts of eastern North America, where it was once valued as an ornamental plant for coastal restoration.Lieberman AS, O'Neill CR. 1988. Vegetation use in coastal ecosystems. Information Bulletin (Cornell Cooperative Extension Publication), 198: 1 – 31. It has also been introduced to Australia with the planting of marram grass.Weeda EJ. 1987. Nederlandse oecologische flora. Wilde planten en hun relaties. IVN, Haarlem, Amsterdam, the Netherlands.
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. More rarely, it can be found growing on rocky coasts with patches of sand interspersed between artificial hard coastal protection features with a similar structure to shingle. In northern Britain, its distribution is limited by the lack of suitable dune systems on which to grow.Doody JP. 2008. Sand Dune Inventory of Europe. National Coastal Consultants, EUCC - The Coastal Union, in association with the IGU Coastal Commission, Leiden, The Netherlands. 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.
Sea holly is associated with various shingle and strandline communities, where it may be scattered within the vegetation. On shingles, sea holly occurs within Honckenya peploides-Cakile maritima strandline community above the tidal limit Rodwell JS (ed.). 2000. British Plant Communities. Vol. 5. Maritime Communities and Vegetation of Open Habitats. Cambridge University Press, Cambridge, UK On dunes, sea holly may be found growing in the Elymus farctus ssp. boreali-atlanticus foredune community, the pioneer vegetation on foredunes, with Elytrigia juncea (E. farctus) as a dominant species.
Sea holly is a poor ecological competitor that generally thrives in open areas,Stasiak J. 1986. The population size of Eryngium maritimum L. on the Polish Baltic Sea coast. Biologia 7: 65–75. declining when habitats are invaded by shrubby species such as Rosa rugosa, Hippophae rhamnoides, Elaeagnus commutata and Salix repens due to substantial shading effects This is because sea holly is a light-demanding plant,Ćwikliński E. 1972. Rozmieszczenie mikołajka nadmorskiego Eryngium maritimum na wybrzeźu szczecińskim. Chronmy Przyrode Ojczysta 28: 21 – 29. although it is protected against water stress through excessive insolation thanks to its succulent equifacial leaves.Eberle G. 1979. Unsere Stranddistel (Eryngium maritimum). Zur Lebensgeschichte einer stark gefährdeten Pflanze. Verhandlungen Natur und Heimat und Naturhistorisches Museum 16: 73–94.
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.Burmester, A. 2008. Beiträge zur Biologie und Anatomie ausgewählter Pflanzenarten (Angiospermae) der zentraleuropäischen Küstenflora. Doctoral dissertation, Christian-Albrechts Universität Kiel.
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 countriesIevina B, Rostocks N, Syed N, Flavell A, Ievinsh G. 2019. Genetic diversity and structure of northern populations of the declining coastal plant Eryngium maritimum. Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. . 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.Mabey R. 1996. Flora Britannica. Random House
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.Rjeibi I, Saad AB, Ncib S, Souid S. 2017. Phenolic composition and antioxidant properties of Eryngium maritimum (sea holly). Journal of Coastal Life Medicine 5 (5):212-215. It has been utilised for its diuretic, stimulant, cytotonic, stone inhibitor, aphrodisiac, expectorant and anthelmintic properties.Meot-Duros L, Le Floch G, Magné C. 2008. Radical scavenging, antioxidant, and antimicrobial activities of halophytic species. Journal of Ethnopharmacology 116: 258 - 62. 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.Erdem SA, Nabavi SF, Orhan IE, Daglia M, Izadi M, Nabavi SM. 2015. Blessings in disguise: a review of phytochemical composition and antimicrobial activity of plants belonging to the genus Eryngium. DARU Journal of Pharmaceutical Sciences 25: 53 DOI 10.1186/s40199-015-0136-3
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.