An annual of cereal fields and disturbed ground, chiefly on dry calcareous soils. Rarely, it can arise as a casual from the seed bank during earth-moving. Lowland.
The very substantial decline, already apparent by 1930, has continued since the 1962 Atlas, due to the intensification of arable farming. Populations are usually very small, and large ones tend to be transient. Re-introduction into protected sites is occasionally attempted using seed of English origin.
As an archaeophyte G. tricornutum has a Eurosiberian Southern-temperate distribution.
Light (Ellenberg): 7
Moisture (Ellenberg): 4
Reaction (Ellenberg): 7
Nitrogen (Ellenberg): 4
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.8
July Mean Temperature (Celsius): 16.1
Annual Precipitation (mm): 736
Count of 10km squares in Great Britain: 386
Count of 10km squares in Ireland: 1
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -4.78
RDB Species Accounts
Galium tricornutum Dandy (Rubiaceae)
Corn cleavers, Briwydden Arw
Status in Britain: CRITICALLY ENDANGERED.
Status in Europe: Not threatened.
G. tricornutum is a plant of disturbed ground which, in the past, occurred mainly in arable fields in the warmer parts of southern and eastern England. There are very few recent records. At Broadbalk field, Rothamsted, it grows in an experimental plot which has never received chemical fertiliser. The Broadbalk field supports a reasonably intact traditional arable flora, including Legousia hybrida, Papaver argemone, Ranunculus arvensis, Scandix pecten-veneris and Torilis arvensis. At Wytham, Oxfordshire, G. tricornutum occurred at one time, and possibly still does, in a conservation area of arable land, together with a range of arable weeds including Ranunculus parviflorus, Sherardia arvensis, Veronica persica and Vicia tenuissima.
G. tricornutum is an annual, flowering between May and September. It is almost exclusively an autumn-germinating plant, and therefore tends to be restricted to ground cultivated in autumn and, if in a crop, to a winter cereal. It is thought to be a relatively poor competitor, and in both Britain and continental Europe, is typically found in rather open sites at the extreme edges of fields where the crop is weak or non-existent. Little is known about the longevity of seed in the soil but may be relatively short-lived (Grime, et al. 1987).
G. tricornutum has declined rapidly in Britain. Recorded in 77 hectads between 1930 and 1960, it was reported from only sixteen between 1960 and 1975, seven between 1975 and 1985 (Smith 1986), and is now known apparently in only two or three. The population at Rothamsted is currently very small and threatened, with only 2, 0, 3, 0 and 4 plants seen in the years 1991 to 1995. At Wytham, Oxfordshire, its presence was first confirmed in 1983. In 1984 a minimum of 10,000 plants was estimated, in 1985 it flowered abundantly, but in 1986 no plants appeared (Everett 1988), and apparently none has been seen since. In Cambridgeshire, two plants appeared in 1996 on a roadside verge which was disturbed during roadworks. Its decline in Britain may be attributed to improved seed-screening from the end of the 19th century, and progressive intensification of arable agriculture during this century, including the application of chemicals. However, its susceptibility to herbicides is not known, although the related G. aparine is resistant to many compounds. The species is at the edge of its range in Britain, and the probably short-lived seed-bank confers little resilience on its populations.
This species was formerly widely distributed in the warmer cereal-growing parts of Europe and the Mediterranean countries. It is still quite common in the south of Europe, but it has become very rare in northern European countries, where it is now confined to climatically favourable sites, often occurring with other rare species.
P. J. Wilson
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.