The history, status and conservation management of Cottonweed Achillea maritima (Otanthus maritimus) at Lady's Island Lake, Co. Wexford, Ireland

Abstract

Cottonweed Achillea maritima (L.) Ehrend. & Y.P. Guo (Otanthus maritimus (L.) Hoffmans. & Link) is a distinctive, perennial member of the Asteraceae found on Mediterranean and Atlantic coasts. While formerly recorded from more than thirty coastal sites in Ireland, Great Britain and the Channel Islands it no longer persists at any of these other than at Lady’s Island Lake, Co. Wexford (v.c.H12). Towards the end of the 19^th century and during much of the 20^th the species was recorded as occurring here in abundance; however, over the last half century this population has declined dramatically both in terms of extent and number of individuals such that as of 2021 only ten naturally-occurring plants remained at the site. This paper describes the history of recording of the species, focussing on sites in Ireland, and provides summary details of the populations recorded by the various botanists who visited and studied them. The various initiatives and conservation actions undertaken over the years in an effort to conserve the species are described and illustrated. Results are provided of recent conservation measures for the species and its habitat at Lady’s Island Lake, including the management and protection of remaining plants, restoration of habitat for the species, collection of seed and cutting material for ex situ propagation and the return of ex situ-raised plants to a specially-prepared part of the site where the species formerly occurred. The population of A. maritima at Lady’s Island Lake in 2021 comprised 10 naturally-occurring and 60 translocated individuals, as well as at least 64 young, self-seeded plants that had arisen from seed produced by translocated plants. The causes of the population decline at Lady’s Island Lake are considered and discussed.