Glucocapparin variability among four populations of Isomeris arborea Nutt

Glucocapparin (methylglucosinolate), a putative defense compound, was found to vary between desert and nondesert populations of Isomeris arborea (Capparaceae): Plants from desert populations contained greater concentrations than nondesert plants in four of the five organs analyzed. Immature leaves at desert sites had average glucocapparin concentrations of 9.2 mg/g and 9.4 mg/g, while nondesert sites averaged 6.0 mg/g and 4.6 mg/g. Mature leaves from desert sites had average concentrations of 12.8 mg/g and 7.9 mg/g; leaves from plants at nondesert sites contained approximately one third to one half of those concentrations.