Population Differentiation in the Range Expansion of a Native Maritime Plant,Solidago sempervirensL.

Abstract

Solidago sempervirens, a halophytic goldenrod native to coastal dunes and marshes of eastern North America, has expanded its range inland along roads in parts of the northeastern United States during the past 20–30 yr. This expansion has been concurrent with the application of deicing salts on roadways in winter. During the same period, the species has appeared inland along the St. Lawrence waterway and the Great Lakes of Canada and the United States and near salt mines or seeps in western and west‐central New York. In a greenhouse study of nine populations from coastal Massachusetts to west‐central New York, we asked whether S. sempervirens has a physiological dependence on salt and whether populations differ genetically with respect to ecologically important traits, such as salt tolerance, phenology, and biomass allocation. Progeny from 20 maternal families per population were subjected to three watering treatments: control (no salt), medium salt (2% salinity), and high salt (4% salinity). Phenotypic tr...