Zincophilic root foraging in Thlaspi caerulescens.

•  Thlaspi caerulescens hyper-accumulates heavy metals, and localized root proliferation in response to patchily distributed metals may enhance heavy metal uptake. Here, an experimental assessment is made of the impact of heterogeneous zinc (Zn) supply, and of the contrast between the concentration of Zn in soil patches, on Zn hyperaccumulation, patterns of root placement, growth, biomass allocation patterns and nutrient acquisition in two ecotypes of T. caerulescens . •  Growth of Prayon and Bradford Dale ecotypes (which originate from a heavily contaminated and a less Zn-contaminated site, respectively) was compared in treatments with either heterogeneous or homogeneous Zn supply and in a treatment with no Zn added to the substrate. •  Prayon exhibited enhanced above- and below-ground biomass production, and zincophilic root foraging patterns in response to heterogeneously distributed Zn. The root placement pattern suggested that T. caerulescens may discriminate between patches with contrasting Zn concentrations and produce more roots in patches with higher Zn concentrations. Bradford Dale did not show these responses. •  The T. caerulescens ecotypes may differ in their Zn requirements or may have experienced selection for genetic differences that affect their ability to respond to Zn heterogeneity. Such differences will be important factors in the successful phytoremediation of contaminated soils.