HISTORY, DISTRIBUTION AND ECOLOGY OF MYCELIS-MURALIS (L) DUMORT (ASTERACEAE) IN IRELAND

A comprehensive review of the literature has revealed that Mycelis mur alis (L.) Dumort, wall lettuce, was known in Ireland nearly a century earlier than has been recognised previously. A study of all records fo r M. muralis in Ireland suggests that the number of sites occupied by this species is increasing, and we document its occurrence in 25 vice- counties. Outside the Burren M. muralis is most commonly associated wi th habitats that have been influenced by man, and the evidence indicat es that these populations are a result of chance introduction. These h abitats include walls, roadside banks, rock outcrops and woodland. The majority of the populations identified were found on walls and in sha ded locations in soils with varying pH and nutrient status. However, M . muralis reaches its greatest abundance in Ireland on the limestone p avement of the Burren, although it also occurs in woodland in this reg ion. Previous accounts indicate that M. muralis had only been recorded in the Burren since the 1930s, and no older records have been discove red in this study. In the absence of older records, a definitive judge ment on the status of M. muralis in the Burren may never be possible. Comparisons of plant performance in exposed and shaded environments sh ow that both vegetative and reproductive performance was higher in hig h-light environments. This suggests that an ability to grow in shaded habitats is not necessarily associated with an impaired performance in high-light environments and may not preclude a species from colonisin g exposed situations.