This autumn- or spring-germinating annual occurs on disturbed, sandy shingle and old sea walls, growing on sparsely vegetated ground; also formerly on the banks of rivers and ditches in East Anglia, and, rarely, on paths and cliffs in Essex. Lowland.
L. saligna has suffered a severe decline owing to sea-wall refurbishment and river engineering. It was extinct at about half its known sites by 1930, and survived in East Anglia until 1953. Inundation by sea water caused a dramatic decline in the present Sussex population in the 1990s, but the Essex population is thriving, and benefits from cattle grazing. It was re-found on the Isle of Grain (W. Kent) in 1999.
European Southern-temperate element.
Light (Ellenberg): 8
Moisture (Ellenberg): 4
Reaction (Ellenberg): 7
Nitrogen (Ellenberg): 6
Salt Tolerance (Ellenberg): 3
January Mean Temperature (Celsius): 4
July Mean Temperature (Celsius): 16.7
Annual Precipitation (mm): 601
Height (cm): 75
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 36
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -1.51
Plantatt Conservation Status
RDB Species Accounts
Lactuca saligna L. (Asteraceae)
Status in Britain: ENDANGERED. WCA Schedule 8.
Status in Europe: Not threatened.
L. saligna is now known in only two localities - at Rye Harbour, Sussex, and Fobbing, Essex. At Rye it is largely restricted to patches of disturbed sandy shingle, either where sand has been added as a stabiliser (as along the old railway line), or in slight hollows where shingle has been removed for sea-wall repairs, and along the margins of a metalled road. The vegetation is sparse, and associates, including Arrhenatherum elatius, Galeopsis angustifolia, Geranium robertianum and Plantago lanceolata, are hardly competitors. At Fobbing, the bulk of the population occurs on an old sea-wall, now some distance from the sea, that was constructed in stepped layers from marine alluvium. Here also the vegetation cover is patchy with much bare soil. The most frequent associates are Bromus hordeaceus, Crepis capillaris, Leontodon autumnalis and Lolium perenne, but Bupleurum tenuissimum and Torilis nodosa are locally common. Other smaller populations occur on irregular mounds of alluvium, bucket-dredged from Fobbing Creek, and one colony has established itself recently on the sea-wall of nearby Canvey Island.
It is an overwintering or spring-germinating annual. The flowers, produced from July to September, close before midday and are self-pollinated. Seed is believed to be viable for only about one year (Prince & Hare 1981) and both overwintering and spring-germinating plants are vulnerable to hard winters. Under ideal conditions, plants can become basket-like, producing numerous flowering stems up to a metre high and bearing upwards of 1,000 achenes; but most plants are smaller. A poor competitor under normal conditions, its ability to survive the hottest summers in dry exposed situations, gives it a competitive edge and probably explains the upturn in numbers in recent years. At Rye, the bulk of the population consists almost entirely of tiny entire-leaved plants, but the few surviving the winter become taller and more bushy. At Fobbing the plants appear to be tillered by grazing, and have several flowering stems ascending laterally from a central rosette. In damp weather the capitula fail to open, entrapping the developing seeds, and biting insects also attack the flowering heads making them sticky with droplets of latex, again preventing many of them from releasing their achenes.
L. saligna has been recorded as a presumed native from Middlesex, Kent, Essex, Cambridgeshire, Norfolk, Suffolk and Sussex. Its strongholds were the low crumbling London Clay cliffs, sea-walls of the Thames estuary, the river embankments of the fen country in eastern England, and maritime shingle on the south coast. However, since 1950 the refurbishment of sea-wall defences has resulted in a catastrophic decline. At Rye the population is scattered over a large area, and the tiny plants are easily overlooked. Permanent quadrats installed there in 1991 indicated a total population that year of 50,000 plants, but following a dramatic decline, only about 1,000 plants remained in 1995. Inundation of its habitats by sea water, which became impounded behind the sea-wall during onshore storms, appears to have been the main cause of this decline. In contrast, the population at Fobbing has increased from about 6,800 plants in 1978 (Hare 1986) to 14,500 in 1994 (Otley College 1990; Adams 1994). About half the population occurs on a 600 metre segment of sea-wall that is regularly grazed, and forms the more or less stable core area and upwind seed source. Other smaller sub-populations fluctuate in numbers depending on the level of grazing. Though currently known only from Rye and Fobbing, it is possible that small populations remain undetected along the many km of remote sea and river-walls of south-east England.
At Rye, disturbance of the sandy shingle above the level of saltwater flooding is advantageous, and fencing against hares and rabbits is beneficial. At Fobbing, trampling and grazing by cattle are essential to its survival there, and on areas of sea-wall where grazing is excluded, L. saligna is quickly ousted by Arrhenatherum elatius and other robust competitors.
L. saligna is widely distributed in Europe, most frequent in the south, but ranging northwards to the Netherlands, Germany, Denmark and northern Russia. It extends eastwards to the Altai and Himalayas, and southwards to North Africa from the Canaries to Ethiopia. It has been introduced to North America.
K. J. Adams and A. D. R. Hare