Northern Ireland's Priority Species

Pyrola media – intermediate wintergreen

 

Distribution map

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Pyrola media Sw.
Family: Pyrolaceae

This UK nationally scarce, evergreen, very shy-flowering perennial is recorded in Northern Ireland only rarely and in very small numbers. Throughout Britain and Ireland intermediate wintergreen has undoubtedly been over-recorded in the past for the rather similar P. minor, common wintergreen, with which it often grows. Perhaps partly for this reason, although always rare, it appears to have declined further throughout Ireland, and in the Republic of Ireland seems now confined to the Burren hills in County Clare. It is, however, easily overlooked and seldom searched for diligently. It is listed in the Irish Red Data Book (Curtis & McGough, 1988).

In brief

  • It grows in heaths, glens and scrub in all six counties except Armagh

  • The preferred growing conditions of this wintergreen are in shaded to semi-shaded, damp and mossy, yet well-drained, mildly to moderately acidic, nutrient-poor or slightly basic soils. This suggests a species avoiding biological competition through tolerance of considerable environmental stress

  • Typically in Northern Ireland it grows in heathery spots beneath a canopy of evergreen shrubs on steep, shaded scarps, or on rocky, acidic soils on upland lake shores

  • Intermediate wintergreen is very shy when it comes to flowering in our particular environmental conditions. It has only once been seen flowering in Fermanagh in the last twenty-five years! The flowering season in Britain and Ireland is generally quoted as June – August

  • This species is scarce and in decline with Northern Ireland being the Irish stronghold

  • The cliffs and slopes occupied by intermediate wintergreen are sufficiently steep to limit grazing pressure from sheep and goats, and our damp climate helps minimise the fire risk.

Species description
A perennial species about 15cm tall with a loose rosette of round, stalked leaves and a spike of white bell-shaped flowers.

Life cycle
Intermediate wintergreen is very shy when it comes to flowering in our particular environmental conditions. It has only once been seen flowering in Fermanagh in the last twenty-five years. The flowering season in Britain and Ireland is generally quoted as June to August, the leafless flowering stem bearing 4 to 12 pendulous white flowers. These contain no nectar but are said to attract bees, flies and beetles, which collect and feed on the plentiful pollen. However, several authorities on pollination agree that insect visits to Pyrola species are rare, and self-pollination must be common since most flowers set seed. While the plant possesses a creeping underground stem or rhizome, it is not the usual robust organ one expects, but is instead a very delicate structure of slender dimensions. This buried organ of energy storage and vegetative population increase and spread, however delicate, may well enable the species to survive the occasional heathland fire, accidental or intentional, for grazing management purposes.

Similar species
Common wintergreen (Pyrola minor) is very similar, but the style is short and straight in common wintergreen, longer and slightly curved in intermediate wintergreen. Common wintergreen occupies much more horizontal ground than intermediate wintergreen in light to medium density woodland shade, generally under a mixture of birch, rowan, ash and hazel. Usually common wintergreen appears in considerable quantity in such woods, forming either discrete patches or large carpets of growth, and in season it flowers very much more freely than intermediate wintergreen.

How to see this species
Intermediate wintergreen is extremely difficult to locate. It is present in most of its stations only in extremely small plant numbers. Growing beneath an evergreen heath canopy, it is made even more difficult to find by the fact that many of the individual leaf rosettes are very small, often bearing only one or two leaves. Very rarely plants are present with up to ten fleshy evergreen leaves. At the four current Fermanagh stations never more than 19 rosettes of the species were found on any occasion, and most often only six or fewer, small, non-flowering plants are present. It has only once been seen flowering in Fermanagh in the last twenty-five years, but the flowering season in Britain and Ireland is generally quoted as June to August. Typically in Northern Ireland it grows in heathery spots beneath a canopy of evergreen shrubs on steep, shaded scarps, or on rocky, acidic soils on upland lake shores. It has been found in all six counties except Armagh. Relevant access permissions should always be sought prior to visiting any sites.

Current status
It grows in heaths, glens and scrub in all six counties except Armagh. In County Down it is confined to a few heaths in the very north, while in north-west Fermanagh it has been recorded in just four clustered stations during the last thirty years on the Lough Navar plateau. The main areas for this species are in Counties Antrim and Londonderry. In County Tyrone there has been a marked decline, but at least two stations here have post-1970 records. It appears to have declined further throughout Ireland, and in the Republic of Ireland seems now confined to the Burren hills in County Clare.

Why is this species a priority in Northern Ireland?

  • This species is scarce and in decline with Northern Ireland being the Irish stronghold.

Threats/Causes of decline
Grazing pressure from sheep and goats and damage to heaths through peat-cutting, tree-planting, and more especially, the use of fire to manage heather cover, are factors probably responsible for some or most of this speciesí decline. The natural absence of conifer canopy until recent plantation during the last century, and the previous supremacy of deciduous woodland lasting for hundreds of years, which appears less suitable for this species, must also have been a negative factor influencing the long-term survival of this, and possibly of all species of wintergreen. Being essentially a northern forest and sub-alpine species in Eurasia, current global climatic warming poses a very real danger to the long-term survival of this species in both Britain and Ireland.

Conservation of this species

Current action

  • Areas of the scarps which are its local headquarters in north-west Fermanagh are protected by their ASSI designation

  • Implementation of the Northern Ireland habitat action plan for Oakwoods.

Proposed objectives/actions

  • Maintain the number of viable populations of the species.

What you can do
Records of new sites and estimates or counts of the sizes of populations are always valuable. Send information (including photographs, if obtained) to The Botanical Society of the British Isles – c/o Botany Department, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EUB or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU, cedar.info [at] magni.org.uk, Tel: 028 9039 5256.

Further information

Links
Flora of Northern Ireland

http://www.ehsni.gov.uk/area_interest_sitesview?SiteNo=ASSI201

Northern Ireland Habitat Action Plans

Literature
Curtis, T.G.F. and McGough, H.N. (1988). The Irish Red Data Book 1. Vascular Plants. Wildlife Service, Ireland. Stationery Office, Dublin.

Illustrations in: Gibbons, B. and Brough P. (1992). The Hamlyn Photographic Guide to the Wild Flowers of Britain and Northern Europe. Hamlyn, London.

Fitter, R., Fitter, A. and Blamey, M. (1996). Collins Pocket Guide: Wild Flowers of Britain and Northern Europe. HarperCollins, London. (and many other editions).

Text written by:
Dr Ralph Forbes