Watercress yield and quality vary depending on both genotype and environment: Results from highly contrasting growing systems of California and UK

•Anti-cancer glucosinolates are increased when watercress is grown in a soil system in California, relative to an aquatic system in the UK.•Higher antioxidants were quantified for watercress grown in the UK.•Morphological plasticity in response to contrasting environments was observed for watercress.•Watercress yield was highest in California, but leaf quality better in the UK.