In Britain, this small deciduous tree is restricted to just a few hedgerows in Devon and Cornwall. Reproduction is by suckering; fruit-set varies greatly from year to year, and production of fertile seed is negligible. Lowland.
or alien. P. cordata, which was first recorded in 1870, has always been very rare in Britain, and its low seed-fertility offers little scope for it to spread naturally to new sites. However, the surviving populations now are being bolstered through carefully documented breeding and restocking programmes (Jackson, 1995).
Oceanic Temperate element.
Light (Ellenberg): 6
Moisture (Ellenberg): 5
Reaction (Ellenberg): 5
Nitrogen (Ellenberg): 4
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 5.4
July Mean Temperature (Celsius): 15.9
Annual Precipitation (mm): 1129
Count of 10km squares in Great Britain: 9
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
RDB Species Accounts
Pyrus cordata Desv. (Rosaceae)
Plymouth pear, Gellygen Plymouth
Status in Britain: VULNERABLE. WCA Schedule 8.
Status in Europe: Unknown
P. cordata is a small hedgerow tree up to 10 metres high. It is known from just two localities in Britain, both in south-west England. The once rural hedge bank in Plymouth, where it was first discovered in 1865 (Archer Briggs 1880) is now subsumed within a light-industrial estate, though a few P. cordata trees remain. The second population, verified near Truro in 1989, is within a landscape of small agricultural enclosures. From these intensively managed British locations it is impossible to determine its favoured habitat. However, in Brittany, in addition to hedgerows it is a component of mixed deciduous woodland with oak, holly, beech, hornbeam, birch, blackthorn, hazel and wild service tree. In densely shaded woods it appears to reproduce asexually by suckers only; flowering and fruiting seem restricted to glades and woodland edges.
Because P. cordata is able to produce abundant suckers, it is often difficult to identify individual plants. The two British populations exist on seven sites, six of which are protected as SSSIs. The Cornish sites are separated by up to 1.9 km (Tonkin 1993) and the two in Plymouth by about 1.6 km. In total, over 120 larger stems (over 1 cm in diameter) have been uniquely numbered and more than 460 other small plants recorded and mapped. There is considerable morphological variation between the two populations including the habit, the shape of the leaf, flowering time and the number of carpels. Molecular research has confirmed a genetic difference between the Truro and Plymouth plants but no genetic variation has been found within either population (Jackson, et al.,1997).
The most significant problem for the long-term survival of P. cordata in Britain is likely to be its poor ability to cope with environmental change, which is restricted by poor sexual reproduction of both populations owing to the lack of genetic variation and resultant self-incompatibility. For example, following the best recorded fruit-set during 1992, in Plymouth, 1,178 fruits yielded only nineteen seeds which were either inbred offspring or the result of hybridisation with local domesticated pears. Research on P. cordata has considered its taxonomy, genetics, reproductive biology, ecology and horticulture (Jackson 1995). Since there are only two genotypes, the carefully designed breeding and propagation programme seeks to enhance its genetic diversity. Planting of both genotypes and seedlings raised from controlled hybridisations between them began in November 1995. This programme should be completed by 1999, with plants starting sexual reproduction by about 2010.
The removal of hedgerows and their unsympathetic management have been significant problems. Other threats to the wild populations include pathogens such as fireblight (Erwinia amylovora) and the importation of European genetic material. Theft of experimental native stock has also occurred. Ex situ measures to offset these threats include the cultivation of clonal material in botanic gardens and arboreta, and the long-term storage of seed. In Plymouth, 28 suckers of local origin have been transplanted to semi-natural areas managed as Local Nature Reserves. Three years after planting all have become established and some have started to flower.
The British populations are the most northerly of its largely western European distribution. However, a recent study of European pears (Aldasoro, et al. 1996) has expanded the range of P. cordata to North Africa and the Near East. They also identified a herbarium specimen from a Gloucestershire site as P. cordata. Field surveys may yet reveal its presence at further sites in southern England.
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.