(Research & Reporting of this Page: Peter J. Farrell)
Irish Lady’s Tresses have a hemi-polar distribution with a major gap in the Palaearctic. They simply do not occur in Europe or Russia apart from Ireland and Britain. They belowng to a small group of Irish Plants that have an Atlantic distribution, occurring in North America and the British Isles, but not anywhere else in Eurasia... though they come very close in the Aleutian Islands of Alaska.
Lough Allen and the rest of Ireland:
Lough Allen has at least 200 (previously under-recorded) specimens of S. romanzoffiana in a number of sites arrayed about the lake near the water level. Other established locations in Ireland where S. romanzoffiana may be found include Lough Neagh, Lough Mask, Mayo (at least 200 specimens may also be found here), Kerry and Donegal.
Looking at the Map below will show you how rare this Species is, being totally absent from the rest of Europe and all of Asia. The species is well represented in 4 central Provinces of Canada, Alberta, Saskatchewan, Manitoba and Ontario but decreasing in other areas. Not scure in much of the USA except for New York and Montana (but American population numbers have been very hard to find). All this data is subject to correction. Please email us!
How did they come to occur in such a small place on the edge of Europe?
According to Irish Botanist D.A. Webb, S. romanzoffiana is an Atlantic species. i.e. one of 30 plants native to Ireland (and to a lesser extent to Britain) that are also native to North America, but not found elsewhere in Europe or Asia. These plants are more common the further west in the British Isles one goes, which explains the predominantly North-Western distribution of S. romanzoffiana.
D.A. WEBB: THE FLORA OF IRELAND IN ITS EUROPEAN CONTEXT
“I turn next to the North American species. It is necessary to consider in connection with them two other species which occur in Britain as well as in Ireland, but nowhere else in Europe. These are Eriocaulon aquaticum, known from a few stations in the Inner Hebrides and the extreme westerly point of the Scottish mainland, and Spiranthes romanzoffiana, with a similar distribution in Scotland and a more recently discovered station on the edge of Dartmoor. Whatever explanation covers the presence of these mainly American species in Ireland will also be valid for Britain. In the first place let us dismiss any notion that any of them have been introduced by man. For the Eriocaulon and the Spiranthes this has never received serious consideration...
How, then, do they come to exist as natives on the extreme northwest fringe of Europe? The answer is surely given by a study of Hultén’s Amphi-atlantic plants. One does not explain the distribution of a plant by giving it a new name, but the data presented by Hultén show that there are dozens of species which straddle the North Atlantic but are absent from the arctic and subarctic regions of Asia....
Doubtless their European range was once somewhat greater than it is now, but there is no reason to suppose that it extended very far eastwards. Under what conditions the floras of North America and of northwestern Europe were in contact, nor how long ago, we do not know, but it must have been at any rate before the last glaciation. Some of the amphi-atlantic plants doubtless survived this glaciation further south than Ireland, but as our four species survive today in Labrador or central Newfoundland it is not asking the impossible that they should have survived the last glaciation in some sheltered nook, perhaps on land now submerged by the rise in sea level, off the coasts of Scotland and Ireland. The fact that Eriocaulon is known as a post-glacial, and very probably as an interglacial fossil in Irish deposits provides strong corroborative evidence for this suggestion; as does the fact that the Irish populations differ in chromosome number from at any rate most of the American plants. Certainly this hypothesis seems to me to be much less improbable than the only real alternative - that all have been introduced in the last few thousand years by the transatlantic flight of diligent birds.”
Abstract: Journal of Life Sciences, Royal Dublin Society vol. (1983), 143-160.
The Boyle Medal Discourse, 1982
All Irish Lady’s Tresses now found in Britain are in its stronghold area of western Scoland. But even here it is in reducing numbers. Evidence of its decline in Scotland is shown in a Scottish National Heritage survey undertaken between 1995 and 1996. 58 out of 69 populations that had been recorded before 1990 were not found. No Scottish location recorded before 1981 is now known to be still present, although in some cases plants occur nearby. Indeed, while new sites continue to be discovered here on a yearly basis, most of these comprise only one or two specimens.
One isolated site has existed in Devon. However, according to a BARS (Biodiversity Action Reporting System) 2005 survey, specimens here are in decline. The extent of its decline is unclear. As of January 2004, S. romanzoffiana had not been seen in the Devon area for 8 years and may be extinct.
Europe and Asia:
S. romanzoffiana does not occur in mainland Europe, and its sole foothold is on the western shores of Britain and Ireland.It is not known to exist anywhere else in the Palearctic region. Claims for its occurence on the Kamchatka Peninsula in Eastern Russia are uncorroborated, and may be refuted by the Checklist of Panarctic Flora (Komarov Botanical Institute, Russian Academy of Sciences) which recently listed them as solely occuring in Arctic regions of Alaska and Hudson Bay.
The Nearctic region of North America has a far more widespread population. From Alaska through Yukon and British Columbia to Maine and Massachusetts, it is found in most or all component counties. The extent of its range reaches to California and Arizona in the South-West, and to Ohio and Pennsylvania in the East. Very small (and likely soon to be extinct) populations have been found in Northern Mexico. Of the 29 US states in which it currently occurs, S. Romanzoffiana is “exploitably vulnerable” in New York, “threatened” in Iowa and Ohio, and “endangered” in Illinois, Indiana, Massachusetts, and Pennsylvania.
Climate forecast models indicate that S. Romanzoffiana populations may continue to move further northwards, becoming increasingly rare in the USA.
Seed-set failure of specimens in the British Isles may restrict Palearctic development of S. romaznoffiana. Nearctic production is somewhat prolific in comparison (75% of examined specimens bore fruit).
Further research must be undertaken to establish the development and somewhat unexplained fluctuations in S. romanzoffiana populations in the British Isles and, for us, the Lough Allen population needs to be studied and recorded both in distribution and in behaviour and reproduction. It is not known how this unique plant came to be present in Lough Allen, or whther it has been continuously present here since the Ice Age, or how it survives and occupies new territory when, as yet, seed production as not been proven in Ireland.
Study Goals: 2009 - 2012:
- Distirbution: Hopefully, this year (2009) an even fuller picture of this species in Lough Allen may be obtaned. Unfortunately,at the time of writing, water leves are high; just as plants should be starting to emerge and flower. Many specimens recorde last year will presently be under water!
- Reproduction: i.e evidence of fertilisation (Bees) and seed setting.