Armeria maritima subsp. intermedia, a rare archaeophyte in SE Finland: history, biology and conservation

The structure of an isolated population of Armeria maritima subsp. intermedia (Marsson) Nordh. (previously identified as subsp. maritima) was studied in the communes of Hamina and Vehkalahti in SE Finland. In addition to field studies, some experimental data on seed germination and seedling growth were gathered in the laboratory. In the field surveys carried out in 1987 and 1988, a total of 10 separate populations were found along the shores of the Gulf of Finland. Some of these comprised only a few individuals, whereas the largest population, with thousands of individuals, occupied an area 170 m long and 2—30 m wide. The origin of the local populations in Hamina and Vehkalahti is not completely clear; the species has probably immigrated in the ballast sand of sailing ships. Laboratory experiments corroborated field observations on the sensitivity of Armeria maritima (Miller) Willd. to shading. Both growth and flowering were affected by decreasing levels of irradiance. Thus, the species requires either naturally open or managed sites to survive. It deserves some protection, since it reaches the NE limit of its distribution in Finland.