Spiranthes romanzoffiana Cham.
Family: Orchidaceae
This attractive wild orchid is distributed right across North America. It was first described scientifically from plants found on the island of Unalaska by Adelbert von Chamisso, the botanist on a Russian expedition which visited the Aleutian Islands of Alaska in 1816. In Europe, it is confined to Ireland and western Great Britain. The fact that the British and Irish populations are widely separated from the American by the Atlantic Ocean raises interesting questions about their origin. Some botanists believe this plant to have arrived only recently from North America, perhaps carried as seed on the feet of migrating birds.
In brief
Species description
The plant grows to about 30cm tall, but often much shorter, with long, narrow leaves arranged up the stems. The flowers are tubular, whitish or cream-coloured, scented, and arranged in three slightly twisted rows along the spike.
Life cycle
The flowering period is from the end of July to the end of August. The flowers are insect-pollinated. Seed capsules split open and the tiny seeds are wind-dispersed. It is often stated that this plant does not normally set seed, but this is incorrect. Plants are perennial, tending to multiply vegetatively by formation of new root tubers and shoots and death of older parts. During winter food is stored in the fleshy tuberous roots. Like most orchids, the roots are infected by a fungus, called a mycorrhizal fungus, which assists the orchid in absorption of important nutrients from the soil.
Similar species
Within Northern Ireland there are no similar species. The autumn lady's-tresses (Spiranthes autumnalis) occurs in other parts of Ireland, and is somewhat similar, but flowers at a much later date.
How to see this species
The plant was not found in Northern Ireland until the 1890s, but is now known from a number of sites around Lough Neagh, Lough Beg, the Mourne Mountains, the Antrim Hills, and the shore of Upper Lough Erne. The best site to see it is probably near Church Island on the marshy western shore of Lough Beg in County Londonderry, but numbers of plants vary from year to year, and grazing by animals may make it difficult to find. In general, it prefers wet or waterlogged non-acidic fen or marsh, but plants have also been found in acidic conditions in the Mourne Mountains. Most sites are at a low altitude, but some are at up to 300 metres in hill districts. Sites are best visited between late July and the end of August.
Current status
Because of the ease with which this plant can be overlooked, it is difficult to assess whether the considerable number of new sites found since 1960 outside its ‘classic’ area of the Lough Neagh basin is a real expansion of the plant or the discovery of long-existing colonies. There has, however, been a real reduction in the number of sites in the Lough Neagh basin. This orchid is legally protected from uprooting or destruction under the Wildlife Order (NI), 1985.
Why is this species a priority in Northern Ireland?
It is a UK Priority Species - the UK holds the largest population of this plant in Europe - and Northern Ireland has about one-third of the total UK population. It also holds about 50% of the total Irish population. Outside North America, this species is only found in Great Britain and Ireland.
Threats/Causes of decline
There appears to have been a real reduction in the number of sites around Lough Neagh, Lough Beg and along the lower River Bann in the past forty years. This may be because of over-grazing and reduction in the water-level of the loughs. The loss of the lower Bann-side plants from the Kilrea area, where it was first discovered in 1892, can be attributed to the sites being buried under material dredged up from the river in the 1930s. A 1980 site from the Mourne Mountains has been destroyed by agricultural improvement.
Conservation of this species
Current action
Some sites for this species are designated as Areas of Special Scientific Interest by the Environment & Heritage Service.
Proposed objectives/actions
What you can do
Records of new sites and sizes of populations are always valuable. Send to The Botanical Society of the British Isles - c/o Department of Botany, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU Tel. 028 9039 5256
Further information
Links
Flora of Northern Ireland
Species Action Plan (all-Ireland)
Literature
Foley, M. & Clarke, S. ( 2005) Orchids of the British Isles. Griffin Press/Royal Botanic Garden Edinburgh
Harrap, A. & S. (2005) Orchids of Britain & Ireland. A.& C. Black, London.
Text written by:
Paul Hackney
iNaturalist: Species account : iNaturalist World Species Observations database