Irish lady's tresses (Spiranthes romanzoffiana)

KingdomPlantae
PhylumAnthophyta
ClassLiliopsida
OrderOrchidales
FamilyOrchidaceae
GenusSpiranthes
SizeStem length: up to 30cm

Classified as Near Threatened in Northern Ireland, and protected under Schedule 8 of the Wildlife (NI) Order.

This beautiful orchid has white flowers that climb up the stem in three closely woven spirals. The leaves are clustered around the base of the stem and resemble those of grass. The group of orchids known as ‘lady’s tresses’ are believed to have been so-named from the resemblance of the spiral florets to locks of braided hair.

The European range of this orchid covers western Scotland, Northern Ireland and the Irish Republic. There is also one site in south Devon. However, the chief home of the Irish ladies’ tresses is North America. It is possible that the British and Irish plants originate from refugia in the Hebrides and Ireland as the glaciers retreated about 8000 years ago, after the last Ice Age.

Irish lady’s tresses is a plant of wet marshy ground, wet meadows near water bodies and bogs. It prefers nutrient poor soil, especially that which is flooded at intervals, and often occurs on grazed meadows in open sedge-rich lawns.

This orchid produces its beautiful flowers in July and August. Despite the fact that the plant flowers regularly, no cross-pollination has ever been confirmed in this country and no seed has yet been recorded. It is still not clear how Irish lady’s tresses reproduces in the UK and Ireland, although recent genetic research has suggested that the northern populations of Scotland have reproduced sexually in the recent past. The plant also seems to reproduce vegetatively, although again it is not clear how.

Irish lady’s tresses is an important plant as the UK and Ireland populations are the only remaining examples of the species surviving in Europe. Although the UK Biodiversity Action Plan lists the use of fertilisers and herbicides as possible threats, the main threat seems to be too little or a lack of grazing in Scotland, which allows taller competitive vegetation to invade the sites.

Irish lady’s tresses is listed in the UK Biodiversity Action Plan and is included in Plantlife’s Back from the Brink conservation programme. A survey in 1995 - 1996 by the Royal Botanic Gardens, Edinburgh for Scottish Natural Heritage, turned up more specimens of this species than were previously thought to exist. Although the UK and Ireland sites represent the entire European population of this species, at present just under half of its sites in Scotland have statutory protection. It is therefore of paramount importance that the sites are protected and their management, and that of the surrounding land, is altered to suit the species.

Part of the plan to preserve this species is to encourage more landowners, on whose property the flower grows, to adopt more traditional grazing regimes that would benefit this plant, hopefully supported by one of the agri-environment schemes designed to help many of our threatened plants. It is also likely that studies will also be carried out to discover why the UK’s plants do not seem to be able to cross-pollinate and produce seed. This will involve studies of populations in Ireland and Northern Ireland, as well as the populations of this lovely orchid in North America.

For more on Plantlife, the wild plant conservation charity see:
http://www.plantlife.org.uk

Information supplied by English Nature.
http://www.english-nature.org.uk