The dose-response of two horticultural plant species (Brassica chinensis L., and Helianthus annuus L.) to two light Rare Earth Elements (REEs), namely lanthanum and neodymium, in-vitro, was investigated. The phytotoxicity of the studied REEs was determined by measuring the aboveground and belowground biomass of the plant parts, and the chlorophyll production. Based on these measurements, inhibition concentration causing 50 % decrease (IC50) in plant biomass and total chlorophyll were calculated. Moreover, the available ionic species of La and Nd in the media for plant uptake were predicted using Visual MINTEQ. The concentration of these elements were measured in different plant tissues to assay the ability of these plants to hyperaccumulate La and Nd. It was observed that La and Nd, at lower dosages (

Keywords:rare earth elements;phytotoxicity;hyperaccumulation;inhibition concentration;translocation factor