It is also found in inland salt flats such as the Pannonian grasslands of Hungary, and it is widely established outside its range in temperate regions of both the north and south hemispheres.

The inflorescence is a false raceme up to 5 cm long and laterally compressed, with numerous clusters ("triads") of 3 one-flowered spikelets.

The mature spikes become brittle, and break up into small clusters of fruits, which are often dispersed by floodwaters in the winter, or by the movement of livestock.

[1] The name Hordeum marinum was coined by the English botanist William Hudson in his Flora Anglica of 1778, giving as a synonym the pre-Linnean polynomial Gramen secalinum maritimum minus ("lesser sea meadow-barley").

[8] In France its distribution and status follow the same pattern as in Britain: it is mostly restricted to places near the coast, with just casual populations inland.

It is also a characteristic plant of the Pannonian inland salt grasslands of south-eastern Europe[10] and, very occasionally, it is found as a roadside halophyte, many miles from the sea.

[11] It needs a lack of competition from other plants, which is usually created by fluctuating water levels or some form of disturbance, such as trampling and grazing by livestock.

In Europe, however, it is considered a characteristic species of several EUNIS habitats: There are several fungi that attack sea barley: the smut fungus Ustilago bullata produces galls in the flowers, while Tilletia controversa creates smut balls in the seeds; meanwhile, several species cause damage to the leaves, including barley powdery mildew, Puccinia hordei (including P. hordei-murini and P. hordei-maritimi), and a fungus called stem rust is known to infect the culms.

There is also an aphid, Metopolophium dirhodum which has been found on sea barley, and a species of thrips, Limothrips angulicornis, which feeds on the leaves.