An annual or short-lived perennial of compacted sandy or gravelly soils, often with chalk or limestone fragments. Its habitats are generally kept open by seasonal standing water or other disturbance, and include forestry rides, golf courses, car parks, disused gravel-pits and disturbed areas in short grassland. Lowland.
Intensive surveys since the 1962 Atlas have shown H. glabra to have a wider distribution in East Anglia, with new sites still being discovered. However, it is presumed extinct in Cambridgeshire, where it was last seen in 1990. It has appeared as a casual in many sites, possibly as a garden escape, and is sometimes naturalised.
Eurosiberian Temperate element.
Light (Ellenberg): 8
Moisture (Ellenberg): 5
Reaction (Ellenberg): 6
Nitrogen (Ellenberg): 2
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.2
July Mean Temperature (Celsius): 16.1
Annual Precipitation (mm): 624
Height (cm): 5
Perennation - primary
Perennation - secondary
Life Form - primary
Life Form - secondary
Comment on Life Form
Clonality - primary
Count of 10km squares in Great Britain: 16
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: 0.83
RDB Species Accounts
Herniaria glabra L. (Caryophyllaceae)
Smooth rupturewort, Llys y Fors
Status in Britain: LOWER RISK - Near Threatened.
Status in Europe: Not threatened.
H. glabra is a plant mainly of eastern England, where it grows in compacted sandy or gravelly soil, often with some chalk or limestone fragments. It cannot withstand close competition, so is chiefly found where disturbance by vehicles or seasonal standing water keep an open habitat for germination. In Norfolk it is generally restricted to well-used rides in pine forests, but in Suffolk and Lincolnshire it grows in disused gravel pits (especially if they hold water in winter), on golf courses, gravelled car parks, and in also in disturbed areas within short grassland. Whilst an open situation is usually favoured, healthy plants can be found in forest rides shaded by mature pines. Frequent associates include Achillea millefolium, Daucus carota, Erodium cicutarium, Holcus lanatus, Plantago coronopus, P. lanceolata, P. major, Reseda lutea and Trifolium repens.
H. glabra is a short-lived, mat-forming perennial. It is winter green, apparently unaffected by frost, and its long tap-root (up to 34 cm long) enables it to withstand drought. Mature plants flower profusely, and can attain a diameter of 40-50 cm. It can flower and fruit in its first year, even as a tiny plant 2 cm across. It flowers from June to October, each flower producing a single seed. Germination is in spring or autumn, whenever conditions are suitable. Bare ground is necessary for germination, but it must be compacted to preserve moisture. Populations in a favourable site can reach several hundreds in some years, then decrease if competition is too great. Seed is viable for at least ten years, so colonies can reappear even after a long absence.
It is now confined as a native plant to the Norfolk and Suffolk Breckland, and Lincolnshire. The most recent loss was from Cambridgeshire, where sites have been destroyed and it has not been seen since 1990. In Norfolk it is maintaining a steady population in twenty localities with new sites still being discovered. In Suffolk, one site holds populations numbered in thousands, whilst three sites have only a few plants. In Lincolnshire, the two remaining sites maintain stable, though small, populations. Sites have been lost in these counties during the last twenty years, chiefly through changes in land use, including gravel extraction and dumping, or by a lack of disturbance. H. glabra has appeared as a casual, persisting for several years in scattered localities north to Lanarkshire. Since it is listed in seed catalogues, these plants are presumed to have originated from gardens. It was reported in 1791 at West Sole, Weston-super-Mare, but this has been regarded as an error (Roe 1981). It was recorded nearby, in 1946, at Ellenborough Park, on the site of a 1940s army camp, where it still survives. These plants could have been introduced from the Breckland, an area long used by the army.
The main threat is a change of land use. Conservation management is difficult, since the plant requires considerable use of the site to compact the soil and to prevent more vigorous species crowding it out. In Norfolk, the rotation of forestry operations, including the use of vehicles in rides, seems ideal, and it is possible that there is effective dispersal of seed or fragments of plants on the wheels of vehicles.
It ranges from southern Europe northwards to southern Scandinavia, occurring also in North Africa and Asia as far east as India.
J. E. Gaffney
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
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Jalas & Suominen (1983)
1965. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
1999. British Red Data Books. 1. Vascular plants, edn 3.