This stoloniferous perennial herb has been recorded in a variety of wetland habitats with fluctuating water levels, including the margins of dune-slack pools, reed-fen, clay-pits and the banks of rivers, ponds and ditches. In Ireland it is often recorded from turloughs. Flowering and seed production can be poor. Lowland.
The long-term decline of T. scordium in England, apparent from the 1962 Atlas, has continued as a result of drainage, reclamation and eutrophication of its wetland habitats. Although remaining populations are apparently stable, they are threatened by lack of management, scrub encroachment and shading. It is stable in Ireland.
Eurosiberian Southern-temperate element.
Count of 10km squares in Great Britain: 24
Count of 10km squares in Ireland: 12
Count of 10km squares in the Channel Isles: 1
Atlas Change Index: -0.64
RDB Species Accounts
Teucrium scordium L. (Lamiaceae)
Status in Britain: VULNERABLE. WCA Schedule 8.
Status in Europe: Not threatened.
T. scordium is a lowland plant of dune-slacks, river banks, ditches and pits on moist calcareous soils. Dune-slacks now hold much the largest populations in Britain, where it grows in open communities around the damp margins of dune-slack pools. Common associates include Agrostis stolonifera, Anagallis tenella, Hydrocotyle vulgaris, Pulicaria dysenterica, Ranunculus flammula and Salix repens. Though open habitats are most favourable, it will survive for a time in closed communities dominated by grasses (even amongst Rubus and Salix bushes), but perhaps only where grasses and shrubs are kept in check by rabbit-grazing. There is some evidence that rabbits graze selectively, avoiding the T. scordium. In contrast, the plant seems to survive well where there is a thick moss carpet. In its other habitats, it also occurs in fairly open semi-aquatic communities, with such species as Carex acutiformis, Filipendula ulmaria, Iris pseudacorus, Lythrum salicaria, Mentha aquatica and Rumex hydrolapathum.
T. scordium is a perennial plant with a stoloniferous creeping rootstock and erect or decumbent stems up to 50 cm high, but often much shorter. The pale pink-purple flowers appear from June to October. Flowering and seed production may be poor and erratic in dry years, and the plant requires open sites for germination and seedling growth. Colonies may be irregular in appearance, re-establishing themselves in areas bared of vegetation. Studies in the Netherlands have shown that dune-slack colonies of T. scordium decline during periods of drought, and years of above average rainfall are beneficial (Laan & Smant 1985).
This species has suffered a great decline, and currently occurs at only two sites, in Devon and Cambridgeshire. The only other post-1970 record is from Stallode Wash, Suffolk where it was apparently unknown between about 1830 and 1976. However, the newly-discovered colony persisted only until 1979, the site having become dominated by Phragmites australis. It formerly occurred in several counties from Berkshire to Yorkshire, though the East Anglian fenland appears to have been its stronghold. Sites have been lost mainly through drainage and land claim. Devon now holds by far the largest populations, several thousand plants occurring in a dozen or more dune-slacks at Braunton Burrows. The population is probably stable at the present time, colonies appearing at new sites whilst disappearing at others as a result of competition. However, a possibly falling water table and overgrowth of shrubs may threaten it there. In the Cambridgeshire pit, the colonies of T. scordium have declined recently because of overgrowth by more vigorous species. Ground must be cleared to provide the right conditions for the plant to re-establish. Water quality is probably important to the plant's survival, and eutrophication appears to be particularly detrimental.
T. scordium is still abundant in some parts of western Ireland, but is now extinct in the Channel Islands. It occurs in most European countries, except Iceland. However, it is declining in many, and is regarded as endangered or vulnerable at least in the Netherlands, Switzerland, the Czech Republic, Germany and Denmark. It also occurs in western Siberia and the Aral-Caspian region.
M. J. Wigginton
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.