Salicornia is a genus of succulent, halophytic (salt-tolerant) flowering plants in the family Amaranthaceae, in the order Caryophyllales. Its members are small annual herbs that look almost cactus-like in miniature: prostrate to erect stems are simple or many-branched, apparently jointed, and fleshy when young, while the leaves are reduced to tiny fleshy scales fused to the stem. The overall morphology is so reduced that dried herbarium specimens are notoriously difficult to identify, and species boundaries in the genus have been the subject of repeated taxonomic revision.
Glassworts inhabit coastal salt marshes, tidal mudflats, mangrove fringes, and inland saline habitats such as the shores of salt lakes, where they often form the lowest, most salt-soaked band of vegetation that few other plants can tolerate. They use the conventional C3 carbon fixation pathway and depend on a limited but real intake of salt; somewhat counterintuitively for plants of waterlogged-looking ground, they do not thrive where the soil is permanently waterlogged. The succulent stems store water and dilute internal salt concentrations, the standard halophyte strategy.
The genus was established by Carl Linnaeus in Species Plantarum in 1753, with Salicornia europaea as the type. Modern molecular work has dissolved several long-standing segregate genera back into Salicornia: Plants of the World Online now lists Arthrocnemum Moq. and Sarcocornia A.J.Scott as heterotypic synonyms, and the Australian Plant Census likewise sinks Sarcocornia, Arthrocnemum, and Halocnemum here. POWO recognises 53 accepted species; Wikipedia cites a figure of roughly 60. Distribution is genuinely cosmopolitan for a halophyte genus, spanning temperate and subtropical coasts and inland saline areas across North and South America, Europe, North and East Africa, southern Africa, much of Asia from Iran to China and Japan, and Australasia.
Beyond their ecological role, Salicornia species are economically important. Several — most famously S. europaea, S. bigelovii, S. virginica, S. rubra and the South Asian S. brachiata — are eaten as the vegetable variously called samphire, sea beans, sea asparagus, or picklegrass. S. bigelovii has been cultivated experimentally with seawater irrigation as a candidate biofuel and forage crop, and the ashes of glassworts were a historical source of soda used in soap- and glass-making, which is the origin of the English name "glasswort."
Etymology
The genus is most widely known by the English names glasswort, picklegrass, marsh samphire, and (in coastal cookery) sea beans, sea asparagus, or beach asparagus. "Glasswort" recalls the historical use of the plants' soda-rich ashes in glassmaking, while "samphire" is an anglicisation of the French "herbe de Saint-Pierre," St. Peter's herb. Atlas of Living Australia records the Noongar (Yuat) name Milyoo for samphires in Western Australia. French-speaking Atlantic Canadians colloquially call them "tétines de souris," literally "mouse tits," after the shape of the swollen jointed stems.
Distribution
Salicornia is genuinely cosmopolitan for a halophyte. POWO records its native range as the temperate and subtropical coasts and saline inland areas of the Northern Hemisphere and southern Africa, with documented occurrences in North America from Alaska to Mexico, in South America in Argentina, Chile and Peru, across Europe from Great Britain through the Mediterranean, throughout Asia from Iran to China and Japan, in northern, eastern, and southern Africa, and in Oceania including New Zealand and Australia. POWO additionally lists the genus as introduced in Hawaii and Michigan. Atlas of Living Australia recognises three native Australian species (S. blackiana, S. globosa, and S. quinqueflora), and SEINet documents the genus across the US Southwest in saline habitats from Arizona and New Mexico.
Ecology
Glassworts are obligate halophytes that colonise the saltiest, most exposed bands of coastal salt marshes, tidal flats, mangrove edges, and inland salt-lake shores — habitats where competition from non-halophytic plants is essentially absent. They use the standard C3 photosynthetic pathway rather than the C4 or CAM systems found in some other succulents. Despite their wet-looking habitat, plants do not grow well in permanently waterlogged soils and require a limited but consistent salt input. The succulent jointed stems serve as both the photosynthetic surface and the salt-diluting water store, while leaves are reduced to fleshy scales. The genus is also part of the salt-marsh food web for invertebrates: Lepidoptera larvae, including Coleophora case-bearers, feed on Salicornia.
Cultivation
PFAF reports that Salicornia tolerates maritime exposure and grows in sandy or loamy soils across a neutral-to-alkaline pH range, including frankly saline soils that would kill most ornamentals. It prefers moist conditions but tolerates drought, accepts full sun or part shade, and tops out around 0.6 m. Wikipedia notes that S. bigelovii has been grown commercially and experimentally under direct seawater irrigation, with added nitrogen — often supplied as aquaculture effluent — as the main nutrient input. This makes it one of the few crop plants that can be raised on land and water that conventional agriculture cannot use.
Propagation
PFAF describes seed as the standard route: sow in spring under glass, prick out seedlings individually, grow them on indoors through the first winter, and plant out after the last frosts. Division of established clumps is also viable.
Cultural uses
Salicornia has been used for food and industry for centuries. Several species — most prominently S. europaea, but also S. bigelovii, S. virginica, S. rubra and the South Asian S. brachiata (umari keerai) — are eaten as a vegetable known by many regional names: samphire and marsh samphire in Britain and France, sea beans, sea asparagus, beach asparagus, picklegrass and crow's foot greens in North America. The young shoots can be eaten raw, with a salty-brackish taste, or cooked; in Hawaii they are often blanched and used as a salad topping. Industrially, the soda-rich ashes of glassworts were historically burned to make alkali for soap- and glassmaking, which is the source of the English name "glasswort."
Taxonomy notes
Salicornia sits in subfamily Salicornioideae of the Amaranthaceae (Caryophyllales). The genus was established by Linnaeus in 1753 with S. europaea as the type species. Recent molecular phylogenetic work has caused several previously segregate genera to be sunk back into Salicornia: POWO treats Arthrocnemum Moq. (1840) and Sarcocornia A.J.Scott (1977 publ. 1978) as heterotypic synonyms, and the Australian Plant Census likewise places Sarcocornia, Arthrocnemum, and Halocnemum under Salicornia. POWO recognises 53 accepted species; Wikipedia cites approximately 60 as of April 2022; GBIF records 131 descendant taxa under the genus, a figure that includes synonyms and infraspecific names. The reduced, jointed succulent morphology means dried specimens are difficult to identify, and species delimitation in the genus remains a notoriously hard taxonomic problem.
History
The genus Salicornia was formally established by Carl Linnaeus in Species Plantarum, volume 1, page 3, in 1753, with S. europaea designated as the type species. Wikipedia notes that the lineage likely originated during the Miocene, with its early diversification probably centred on the Mediterranean and Central Asia region before later spreading across both hemispheres.
