Hordeum marinum

Tracheophyta MagnoliopsidaPoaceaeHordeumHordeum marinum

Ecology

An annual of barish places by the sea, on the trampled margins of dried-up pools and ditches in grazing marshes, on tracks and sea walls, and in the uppermost parts of saltmarshes; also, very locally, beside salt-treated roads inland. Lowland.

Status

Native

World Distribution

Mediterranean-Atlantic element; also in C. Asia and widely naturalised outside its native range.

Broad Habitats

Neutral grassland (includes coarse Arrhenatherum grassland)

Light (Ellenberg): 9

Moisture (Ellenberg): 6

Reaction (Ellenberg): 8

Nitrogen (Ellenberg): 6

Salt Tolerance (Ellenberg): 4

January Mean Temperature (Celsius): 4.3

July Mean Temperature (Celsius): 16.4

Annual Precipitation (mm): 720

Height (cm): 37

Perennation - primary

Annual

Life Form - primary

Therophyte (annual land plant)

Woodiness

Herbaceous

Clonality - primary

Little or no vegetative spread

Count of 10km squares in Great Britain: 146

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 1

Atlas Change Index: -0.85

JNCC Designations

NHMSYS0000459748

Scarce Atlas Account

Scarce Atlas Account: 

Hordeum marinum Hudson

Sea barley

Status: scarce

 

 

This is an annual grass of bare soils along the coast. It favours brackish sites which are occasionally flooded in winter but baked hard and dry by midsummer; so it is frequently found by the edges of dried-up pools and ditches, or on ground on the landward side of sea walls which has been rutted by vehicles or trampled by cattle. Characteristic associates in these open communities include Puccinellia distans, Spergularia marina and the scarce species Polypogon monspeliensis, Puccinellia fasciculata and P. rupestris. In a few places it also occurs on the upper parts of salt-marshes, especially where these are grazed and trampled by cattle or sheep: associates in these sites can include Festuca rubra, Glaux maritima, Juncus gerardii, Parapholis strigosa, Plantago coronopus and Puccinellia maritima.

H. marinum is free-flowering and strictly annual, reproduction being entirely from seed. The mature spikes are very brittle and break tip into little clusters of spikelets which tend to disperse together. Dispersal of spikelets is probably assisted by flooding, as winter flood-lines around pools are often marked the following summer by narrow hanks of H. marinum.  Seedlings occur in spring and autumn but the latter may not survive the winter.

H. marinum appears to be decreasing, particularly along the south coast. This is probably the result of the loss of coastal grazing marsh, filling-in of pools and small ditches, and the strengthening and upgrading of sea defences. It is susceptible to successional changes, tending to be overpowered by perennial grasses (notably Elytrigia atherica), and thus it requires the continuous creation of open ground. 

It is widely distributed in the Mediterranean region, where it grows on both maritime sands and on disturbed ground away tram the coast, and extends along the coast of western Europe to reach its northern limit in the British Isles.

 

 

A. J. Gray

Atlas text references

Atlas (391c)
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.