This slender, often diminutive, annual is primarily a colonist of thinly vegetated or disturbed coastal sites, including coastal banks, sea walls, drained estuarine marshes and the margins of brackish ditches. Inland populations formerly grew on commons and roadsides; it still grows on commons near Malvern (Worcs.). Lowland.
Most of the inland sites for this species were lost before 1930, and the distribution seems to have been largely stable since the 1962 Atlas. It was recorded from the central reservation of the A2 near Dartford (W. Kent) in 1982 but has otherwise shown little tendency to colonise salted roadsides.
European Southern-temperate element.
Count of 10km squares in Great Britain: 161
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -0.97
Scarce Atlas Account
Bupleurum tenuissimum L.
This is a plant of dry, usually brackish, grassland on sea-walls, drained grazing marshes and, less frequently, on the upper (often disturbed) parts of saltmarshes. It typically occurs in short turf with plenty of bare ground, and can be locally abundant in disturbed areas, for example alongside trackways, ditches and spoil dumps, and in areas subject to poaching by livestock.
Associated species are varied, and include several other nationally scarce plants with similar habitat requirements and geographical distribution, e.g. Hordeum marinum, Parapholis incurva and Trifolium squamosum. The only recent inland records are from Worcestershire, where it still occurs on several commons. It is confined to the lowlands.
B. tenuissimum is an annual, flowering from July to September. Seed germinates in autumn and spring, and the fact that plants normally grow in open situations suggests that bare ground is important for germination and successful seedling establishment. As with many annual species, population size can vary considerably from year to year. However, it is uncertain whether it develops a persistent ‘bank’ of buried seed.
B. tenuissimum has disappeared from almost all its inland stations. On the coast, too, there have been some losses, particularly towards the northern edge of its range. Many B. tenuissimum populations are closely associated with sea-walls, and these are likely to be at risk from engineering schemes to upgrade coastal defences.
It is found on the coasts of western Europe northwards to southern Scandinavia (Denmark and Sweden), also locally inland. In southern Europe it occurs by the Mediterranean and from there eastwards to the Middle East.
S. J. Leach
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.
Atlas text references
1994. 'Maritime' plants of roads in Cambridgeshire (v.c. 29). Nature in Cambridgeshire. 36:37-60.
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
1978. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 2. 2 vols.
1994. Scarce plants in Britain.
1980. Umbellifers of the British Isles. Botanical Society of the British Isles Handbook no. 2.