Guest blog by RSPB NI Conservation Advisor Gareth BarehamIrish lady’s-tresses (Spiranthes romanzoffiana) is one of the rarest members of the orchid family in Europe, occurring only at scattered locations on the western seaboards of Ireland and Scotland and one site in England.
Actually one of a very small number of North American ‘amphi-atlantic’ species that found its way across the Atlantic it is considered an ‘honorary native’ of the Irish flora. The species was first scientifically described on an expedition to islands off Alaska in the early 1800s and there are a number of theories as to how the plant may have made its way to our shores. The seeds are tiny and lightweight so might have been blown across the Atlantic or they could have been transported on the feet or feathers of birds blown off course on migration.
First found in Ireland in County Cork in 1810, it was fairly widely reported in Ireland from the late 19th to mid-20th centuries. However, since the 1950s it has disappeared from many of these early recorded locations, a trend also reflected in Scotland, possibly as a result of land use changes and loss of habitat, now very much confined to a few sites, of which the wet grassland at Lough Beg is far and away the single most important single site. Other important locations include the RSPB reserve at Portmore Lough, Gortnagorry ASSI up on the Garron Plateau above Carnlough in County Antrim and the traditionally-managed pastures above the Giant’s Causeway on the north coast. Occasional discoveries at other locations suggest that the species may be somewhat under-recorded, with re-discovery of old sites or new sites or possibly still to be discovered.
The life cycle of Irish lady’s-tresses is still something of a mystery and may partly explain its elusive nature for botanists searching for it. Although its migration to Ireland may have occurred as seeds, it has not actually been observed to set seed and it may be that some form of physical disruption of the roots, such as trampling by animals, is essential in its propagation. It also seems to have a complex life cycle so that botanists tend to find boom and bust periods for it, with flowering, vegetative and ‘underground’ phases over a cycle of seven years or so. In common with other orchids, a fungal associate is possibly crucial to the life cycle.The habitat requirements of Irish lady’s-tresses in its native home in North America are natural wetlands such as muskeg forest and beaver meadows, which will be subject to grazing by natural herbivore species such as elk and deer.
The sites where it has been recorded in Europe display a wide variety of conditions, within a broadly wetland habitat category. These include lake margins, peat bogs, rush pastures and unimproved wet grasslands. It appears to require good top-lighting and at least moderate soil fertility. A preference for seasonal inundation has been suggested, but the species does not favour permanently aquatic conditions. Importantly, such sites where it is found in Northern Ireland seem to be where traditional extensive grazing is still practised and so light grazing and rush cutting where needed may be key to keeping this beautiful little plant in our countryside. This is where organisations such as the RSPB play a vital role. At sites including Portmore Lough we are able to trial extensive grassland management regimes and then use what works for plants such as Irish lady’s-tresses to inform the advice and support we provide to farmers and other land managers. This helps to maintain the best possible conditions for the Irish lady’s-tresses at sites such as Lough Beg, where we have special permission on this private site to provide guided tours for the public to see this very beautiful and special little plant. We are hosting a Lough Beg Orchid Safari on Saturday 4th August (11am to 3pm). Price: £20 or £16 for RSPB members. To book, call our secure booking line 028 9064 5630 (Mon-Fri, 9am to 5pm) or email rspbnievents@rspb.org.uk. More info here: http://bit.ly/OrchidSafari
a very special plant