1. Family: Poaceae Barnhart
    1. Genus: Hordeum L.
      1. Hordeum marinum Huds.

        A member of the grass family (Poaceae), Hordeum marinum is a salt-tolerant wild relative of the economically important cereal barley (H. vulgare).


    Kew Species Profiles

    General Description

    A member of the grass family (Poaceae), Hordeum marinum is a salt-tolerant wild relative of the economically important cereal barley (H. vulgare).

    Sea barley occurs on bare soil on the coast, around dried-up salty pools in salt marshes, and on rare occasions may be found on sandy or stony areas. Its tolerance of high salt levels and the water-logging that commonly accompanies it, makes sea barley a candidate for hybridisation with wheat (Triticum species). Increasing salinity of arable land is a costly problem for farmers worldwide, reducing plant growth and thus crop yields.

    Species Profile
    Geography and distribution

    The UK is at the northern edge of the distribution of Hordeum marinum , where it grows from the south coast of Wales to its northernmost limit at the Wash. It is absent from Ireland and no longer occurs in Scotland. It is also found across the Mediterranean and parts of Central Asia on disturbed inland areas. This species has become extensively naturalised outside its native range.


    Sea barley grows up to 10–40 cm tall with stiff, smooth stems growing singly or clustered loosely together. Stems grow either straight upwards or outwards, spreading from a bent base. Each stem contains 3 or 4 nodes (areas from which leaves emerge). Sheaths (the lower parts of the leaf that wrap around the stem) are smooth and rounded on their backs. The leaf blade is bluish-green and narrows to a fine point at the tip. Membrane-like ligules (outgrowths on the inner side of the junction between leaf sheath and blade) are less than 1 mm in length.

    Flower heads are green or purplish, spike-shaped and bristled, 2.0–6.0 cm long and 1.5–3.0 cm wide. Spikelets (single units of the flower head composed of modified leaves and flowers) occur in groups of three, alternating on opposite sides of the flowering stem. The central spikelet contains a single bisexual flower and joins directly to the flowering stem. Lateral spikelets are sterile and borne on short stalks. On fruiting, spikelets fall from the flowering stem in groups of three. Flowering and fruiting occurs during the summer

    Subspecies of sea barley

    There are two subspecies of sea barley. Hordeum marinum subspecies marinum is distinguished by the wide, wing-like base of the inner glumes (modified leaves at the base of spikelets) of its lateral spikelets. In contrast, H. marinum subspecies gussoneanum has a narrower inner glume that is not winged and a more variable chromosome number. Although H. marinum subspecies gussoneanum is not native to the British Isles, it is widely invasive in Britain and has been present in Guernsey for more than a hundred years. Seeds of H. marinum may colonise outside of their native range, carried as contaminants in imports of agricultural plants.

    Reproduction of sea barley

    Sea barley is an annual that self-pollinates and reproduces solely by seed. It requires an open habitat, performing best in mud that begins to dry during spring and is hard by the middle of the summer. Flooding in winter may help disperse the seeds, as winter flood lines from the previous year are found to contain seed deposits. Seedlings are seen in both spring and autumn; however, it is not known if either of these populations contributes more significantly to persistence of the species.

    Threats and conservation

    The distribution of sea barley around the south coast of England has become patchy as populations at the limits of its distribution disappear. These local extinctions are due to loss of appropriate habitat through filling-in of brackish land, land improvement, conversion of marshland grazing sites and construction of sea defences. These habitat losses have led to sea barley being listed as Vulnerable in the Vascular Plant Red Data List for Great Britain 2005 .

    Another reason for its decline is that annuals such as Hordeum marinum are susceptible to competition from perennial species. Elymus pycnanthus , for example, may take over the saline habitats previously occupied by H. marinum , a problem that can be alleviated by the continuous creation of open areas, which are essential for the establishment and persistence of sea barley.


    Sea barley is tolerant of high salt levels in the soil and also of the water-logging that commonly accompanies high salinity. These qualities have led to sea barley being proposed as a candidate for hybridisation with wheat ( Triticum species), with the aim of producing plants that are more suited to the increasing salinity of arable land, which can result from climate change.

    Adapting Agriculture to Climate Change

    Kew is one of a number of institutions collaborating on the 'Adapting Agriculture to Climate Change' project. This project seeks to combat the threat to global food security posed by climate change and will focus on collecting, protecting and preparing crop wild relatives for breeding programmes.

    Hordeum marinum is an important wild relative of the major cereal grain Hordeum vulgare (barley). Previous studies of H. marinum have found that its saline tolerance makes it a possible candidate for hybridisation with wheat ( Triticum species). It is hoped that introducing traits from wild relatives to crop species will produce hybrids adapted to new climates with different demands.

    Millennium Seed Bank: Saving seeds

    The Millennium Seed Bank Partnership aims to save plant life worldwide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

    Two collections of Hordeum marinum seeds are held in Kew’s Millennium Seed Bank based at Wakehurst in West Sussex.

    See Kew’s Seed Information Database for further information on Hordeum marinum .

    This species at Kew

    Sea barley is not currently grown at Kew, but other Hordeum species can be seen growing here in the Grass Garden.

    Pressed and dried specimens of Hordeum marinum are held in Kew’s Herbarium where they are available to researchers by appointment. The details of some of these specimens, including some images, can be seen online in Kew’s Herbarium Catalogue.

    United Kingdom
    Bare soil on coastlines, margins of dried-up saline pools, disturbed verges inland of sea walls and salt marshes.
    Vulnerable (VU) in Great Britain according to IUCN Red List criteria.

    Barley grasses can cause problems for sheep such as eye injuries, reduced weight gain and inferior wool quality.

    Annual; culms solitary, or caespitose. Culms 10-40 cm long; 3-4 -noded. Leaf-sheath oral hairs lacking. Leaf-sheath auricles absent, or falcate. Ligule an eciliate membrane; 0.5-1 mm long. Leaf-blades 1.5-8 cm long; 1-3.5 mm wide.
    Inflorescence composed of racemes. Racemes 1; single; oblong, or ovate; bilateral; 2-6 cm long. Rhachis fragile at the nodes; flattened. Spikelet packing broadside to rhachis. Rhachis internodes oblong; falling with spikelet above. Spikelets in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 2 in the cluster. Pedicels oblong.
    Companion sterile spikelets well-developed; containing empty lemmas; lanceolate; dorsally compressed; 3-5 mm long; shorter than fertile; deciduous with the fertile. Companion sterile spikelet glumes markedly unequal in width; subulate; 8-26 mm long; winged on margins (upper glume); eciliate on margins. Companion sterile spikelet lemmas 1; exserted from glumes; 3-5 mm long; 1-awned; with 3-5 mm long awn.
    Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 6-8 mm long; falling entire; deciduous with accessory branch structures. Companion sterile spikelets well-developed; containing empty lemmas; lanceolate; dorsally compressed; 3-5 mm long; shorter than fertile; deciduous with the fertile. Companion sterile spikelet glumes markedly unequal in width; subulate; 8-26 mm long; winged on margins (upper glume); eciliate on margins. Companion sterile spikelet lemmas 1; exserted from glumes; 3-5 mm long; 1-awned; with 3-5 mm long awn.
    Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 6-8 mm long; falling entire; deciduous with accessory branch structures.
    Glumes collateral; similar; gaping. Lower glume subulate; 10-24 mm long; 1 length of upper glume. Lower glume margins eciliate. Upper glume subulate; 10-24 mm long. Upper glume margins eciliate.
    Fertile lemma ovate; 6-8 mm long; coriaceous; without keel; 5 -veined. Lemma surface smooth. Lemma apex acuminate; awned; 1 -awned. Principal lemma awn 10-24 mm long overall; limb scabrous.
    Anthers 3; 1.3-1.5 mm long. Ovary pubescent on apex.
    Caryopsis with adherent pericarp; ellipsoid; sulcate on hilar side; hairy at apex. Embryo 0.2 length of caryopsis. Hilum linear; 1 length of caryopsis.
    Europe: northern, central, southwestern, southeastern, and eastern. Africa: north, Macaronesia, and south. Asia-temperate: Soviet Middle Asia, Caucasus, western Asia, Arabia, and eastern Asia. Asia-tropical: India. Australasia: Australia and New Zealand. North America: western Canada, eastern Canada, northwest USA, northeast USA, southwest USA, and Mexico. South America: southern South America.
    Triticeae. CEH.
    Potential for use in crop breeding.



    Found In:

    Afghanistan, Albania, Algeria, Austria, Baleares, Baltic States, Belgium, Bulgaria, Canary Is., Corse, Cyprus, Czechoslovakia, Denmark, East Aegean Is., Egypt, France, Germany, Great Britain, Greece, Hungary, Iran, Iraq, Italy, Kazakhstan, Kirgizstan, Kriti, Krym, Kuwait, Lebanon-Syria, Libya, Madeira, Morocco, Netherlands, North Caucasus, Pakistan, Palestine, Portugal, Romania, Sardegna, Saudi Arabia, Sicilia, Sinai, South European Russi, Spain, Tadzhikistan, Transcaucasus, Tunisia, Turkey, Turkey-in-Europe, Turkmenistan, Ukraine, Uzbekistan, West Himalaya, Yugoslavia

    Introduced Into:

    Argentina Northeast, Argentina Northwest, Argentina South, Arizona, British Columbia, California, Cape Provinces, Chile Central, Chile South, Idaho, Illinois, Japan, Masachusettes, Mexico Northwest, Montana, Nevada, New Jersey, New South Wales, New Zealand North, New Zealand South, Ohio, Oklahoma, Oregon, Pennsylvania, Queensland, South Australia, Tasmania, Utah, Victoria, Washington, Western Australia

    Common Names

    Sea barley

    Hordeum marinum Huds. appears in other Kew resources:

    Date Identified Reference Herbarium Specimen Type Status
    Marshall, E.S. [s.n.], United Kingdom K000790006
    Marshall, E.S. [s.n.], United Kingdom K000790007
    Makins, F.K. [2250], United Kingdom K000790008
    Summerhayes, V.S. [s.n.], United Kingdom K000790009
    Haines, D.M. [1], United Kingdom K000790010
    Williams, L.H. [s.n.], United Kingdom K000790012
    Gamble, J.S. [s.n.], United Kingdom K000790013
    Payne, R. [s.n.], United Kingdom K000790014
    Gamble, J.S. [s.n.], United Kingdom K000790015
    Jenner, J.H.A. [1600], United Kingdom K000790016
    s.coll. [s.n.], United Kingdom K000790017
    Loydell, A. [s.n.], United Kingdom K000790018
    Lousley, J.E. [s.n.], United Kingdom K000790019
    Jones, C. [s.n.], United Kingdom K000790020
    Hubbard, C.E. [s.n.], United Kingdom K000790021
    Horwood, A.R. [s.n.], United Kingdom K000790023
    s.coll. [s.n.], United Kingdom K000790024
    Wallace, E.C. [s.n.], United Kingdom K000790025
    Fraser, J. [s.n.], United Kingdom K000790026
    Cole, L.W. [s.n.], United Kingdom K000790028
    Burtt, B.L. [s.n.], United Kingdom K000790029
    Burtt, B.L. [s.n.], United Kingdom K000790030
    O'Byrne, J.K. [165], United Kingdom K000790031
    O'Byrne, J.K. [169], United Kingdom K000790032
    Webster, M.M. [5961], United Kingdom K000790033
    Summerhayes, V.S. [836], United Kingdom K000790035
    Melville, R. [s.n.], United Kingdom K000790036
    Britton, C.E. [s.n.], United Kingdom K000790037
    Whellan, J.A. [s.n.], United Kingdom K000790038
    Oliver, D. [s.n.], United Kingdom K000790039
    Hosking, A. [s.n.], United Kingdom K000790040
    Townsend, C.C. [s.n.], United Kingdom K000790041
    s.coll. [s.n.], United Kingdom K000790042
    s.coll. [s.n.], United Kingdom K000790044
    Lousley, J.E. [s.n.], United Kingdom K000790045
    Brown, J. [s.n.], United Kingdom K000790046
    T.M. [1369], United Kingdom K000790048
    Hubbard, C.E. [9135], United Kingdom K000790049
    Hubbard, C.E. [s.n.], United Kingdom K000790050
    Hubbard, C.E. [107], United Kingdom K000790051
    Hubbard, C.E. [107], United Kingdom K000790052
    Hubbard, C.E. [s.n.], United Kingdom K000790053
    Townsend, C.C. [s.n.], United Kingdom K000790054
    Dony, J.G. [1480], United Kingdom K000790055
    Prior, C.A. [s.n.], United Kingdom K000790057
    T.W. [s.n.], United Kingdom K000790058
    Johnston, H.B. [3038], United Kingdom K000790059
    s.coll. [s.n.], United Kingdom K000790062
    Baker, J.G. [s.n.], United Kingdom K000790065
    Coates, J. [s.n.], United Kingdom K000790066
    s.coll. [334], United Kingdom K000790067

    First published in Fl. Angl., ed. 2: 57 (1778)

    Accepted in:

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    • [22] Al-Rawi, A. (1987) Flora of Kuwait 2: 1-455. Alden Press Ltd., U.K.
    • [24] Davis, P.H. (ed.) (1985) Flora of Turkey and the East Aegean Islands 9: 1-724. Edinburgh University Press, Edinburgh
    • [25] Meikle, R.D. (1985) Flora of Cyprus 2: 833-1970. The Bentham-Moxon Trust Royal Botanic Gardens, Kew
    • [28] Tutin, T.G. & al. (eds.) (1980) Flora Europaea 5: 1-452. Cambridge University Press
    • [29] (1970) Flora Iranica 70: 1-573. Naturhistorisches Museums Wien
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    • [1] (2013) Botanical Sciences 91: 461-475
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    • [33] (1950) Flora Kirgizskoi SSR 2: 1-315. Frunze : Izd-vo KirgizFAN SSSR
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    • [35] (1932) Flora Turkmenii 1: 1-340. Turkmenskoe gosudarstvennoe izd., Ashkhabad


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