Format: ORAL

Nick Scott(1), Micheline Sheehy Skeffington(2)

(1)Teach Na Tuisceana, Co. Galway, Ireland (2)University of Galway, Galway, Ireland

Five species of heather have disjunct Lusitanian type distributions in Europe. They occur as discrete populations along Irelands west coast, and two also occur on Britains south-west coast. The nearest, or principal other place they occur is in the Iberian Peninsula. None could have survived the last ice age in Ireland or Britain, and migration northwards, leaving 100s of kilometre gaps en route, appears impossible. Erica mackayana (Mackays Heath) does not set seed in Ireland and is restricted to small colonies beside minor routeways inland from the west coast, suggesting it was introduced through smuggling. This was confirmed by a genetic study which found that each Irish population was similar to plants sampled from a different place in north Spain and not to each other. However, while the results are consistent with most of the populations being comparatively recent introductions, the largest, on Roundstone Bog in Connemara, appears to be much older. Other heathers appear to be historical introductions to Ireland, Erica vagans (Cornish Heath) brought on smuggled goods and Erica erigena (Irish Heath) brought by pilgrims traveling on pilgrimage by sea to Santiago de Compostela, but the single population of Daboecia cantabrica (St Dabeocs Heath), is today that extensive, covering all the available habitat in Connemara and South Mayo, that it must have been brought much longer ago. Eleven other Lusitanian plant species occur in western Ireland including Arbutus unedo (Strawberry Tree) shown to be probably introduced 4,300 BP by the first copper miners. Combining the distribution pattens of all those likely to be ancient introductions points at a direct ancient sea crossing from Galicia to western Ireland dating back to the start of the Bronze Age.