A root parasite mainly of Galium mollugo and G. verum, probably perennial and sometimes long-lived. It occurs in stabilised dune grassland, and in scrub and hedge banks on chalk downs and undercliffs. Most populations are small, but some of those on dunes are of a considerable size. Lowland.
Populations of this species on the North Downs (E. Kent) are vulnerable, and may be declining because of habitat change, but those on dunes seem reasonably secure. Native records from other parts of Britain, including Scotland, are now considered to be errors.
European Temperate element, with a continental distribution in W. Europe.
Light (Ellenberg): 8
Moisture (Ellenberg): 3
Reaction (Ellenberg): 9
Nitrogen (Ellenberg): 2
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 4.1
July Mean Temperature (Celsius): 16.4
Annual Precipitation (mm): 782
Count of 10km squares in Great Britain: 5
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: 0.01
RDB Species Accounts
Orobanche caryophyllacea Sm. (Orobanchaceae)
Bedstraw broomrape, Clove-scented broomrape
Status in Britain: VULNERABLE. WCA Schedule 8.
Status in Europe: Not threatened.
In Britain, O. caryophyllacea is restricted to East Kent; the few records from outside the county representing errors in identification or mis-labelling of herbarium specimens. The population at Sandwich Bay is on an established dune system, whilst its other sites in Kent are hedgebanks or scrub on chalk downs and undercliffs.
This species mainly parasitises Galium mollugo and G. verum. It is perennial, and once established, may be long-lived. It flowers in June and July, with flowers at the start of anthesis being noticeably clove-scented. Most flowers produce seed, indicating good pollination. It appears to be an outbreeding species, as isolated single inflorescences or multiple inflorescences from the same clone do not set seed, suggesting a high degree of self-incompatibility. A range of insects including bumble-bees, wasps and stiletto flies have been recorded visiting the flowers and all are likely pollinators. The plant is also able to reproduce vegetatively.
O. caryophyllacea is most numerous at Sandwich Bay, where it can regularly be seen in considerable numbers, with more than 1,000 inflorescences. It has been recorded at six other sites since 1980, all within the Dover-Folkestone area, though one is now lost to development. Most of these populations are small (from one to twenty spikes), although in the latter part of the 1980s, over 60 inflorescences were recorded at two of these sites. However, the chalk cliffs are a fragile and difficult habitat to explore, and it is possible that it may be more frequent in this area than the few records suggest.
Currently, the population at Sandwich Bay seems reasonably secure, but populations on the South Downs may be threatened by habitat destruction as a result of road widening or other development associated with the Channel Tunnel link.
O. caryophyllacea has a widespread distribution in central Europe, extending eastwards to Poland, Latvia, the Caucasus and Iran, southwards to North Africa and northwards to Sweden and perhaps Norway. It is difficult to explain its limited British distribution, since its occurrence in the northern Alps and Scandinavia suggests that its range is not limited by a cooler climate.
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
1978. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 2. 2 vols.
1991. An account of Orobanche L. in Britain and Ireland. Watsonia. 18:257-295.
1999. British Red Data Books. 1. Vascular plants, edn 3.