An autumn-germinating annual of freely-draining substrates. In Norfolk, it has most recently been recorded from the open edge of sandy grass-heath where it abuts a roadway, and in Bedfordshire from a sand-pit. Lowland.
Early British records of Petrorhagia cannot be identified to the two species currently recognised. Current populations in Norfolk date from 1835; it was known at several sites until the 1950s, but not seen again until 1985. Although it is treated here as an introduction, it is arguably native in Norfolk and possibly in Suffolk (Akeroyd & Beckett, 1995). It is well-established in Bedfordshire but a casual elsewhere.
A European Temperate species.
RDB Species Accounts
Petrorhagia prolifera (L.) P. Ball & Heywood (Caryophyllaceae)
Kohlrauschia prolifera auct.
Status in Britain: CRITICALLY ENDANGERED.
Status in Europe: Not threatened.
This species has been recorded from scattered sites throughout southern England. Its status in Britain has been a matter for debate, and it has not always been regarded as a native plant. Whilst it has been undoubtedly of casual occurrence in some places, it is now generally regarded as a relict native in Norfolk and, less convincingly, in Bedfordshire (Akeroyd & Beckett 1995). In Norfolk, its history is well documented from the 1840s, all records being on the light soils of West Norfolk, and most referring to parishes within 5 km of its present known site.
P. prolifera can grow to 50 cm, but is usually only 10-20 cm. Its narrowly linear, grass-like leaves are difficult to spot when the plant is not in flower, especially when it is growing amongst grass. It is an annual, flowering in June to August, the flowers opening singly and not very widely. The seeds have a distinctive reticulate pattern which differentiates them from those of P. nanteuilii which are tuberculate.
In Norfolk a number of records were made in the 1950s, but the plant is currently known at only one site, where it was discovered in 1985 (Beckett 1992). The colony holds it own in the very open vegetation on droughted ground at the edge of a concrete roadway leading into a former military camp. It also spreads into the adjacent ranker grassland on roadside banks, and within the adjacent SSSI. In 1994, about 75 plants were counted: many flowering stems, which were cut during the trimming of road verges, flowered again in early autumn. Another locality nearby is now dense grass at the edge of afforestation and P. prolifera is no longer found there. However, it is likely that its seed is long-lived, and that the plant may yet re-appear there if the habitat is opened up. In Bedfordshire, P. prolifera grows on light sandy soils by a sand pit. The original site was lost in about 1980 through further sand winning, and it was feared that it had become extinct as a result. But twelve plants were seen in 1995 close to the site of the original colony.
P. prolifera is widespread throughout central and southern Europe extending north to southern Sweden, and also occurs in North Africa. It is naturalised in Chile, New Zealand and Australia where it is sometimes a prolific weed on dry sandy soils.
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.