Concentra~ons of constituent isothiocyanate-yielding glucosinolates (IYG) declined seasonally in cauline leaves and stems of Cardamine cordifolia, sampled in montane Coloredo. All five constituents (isopropyl, 2-butyl, isobutyl, benzyl and 2-phenylethyl glucosinolates) were correlated positively with total concentration over the growing season. In contrast, no seasonal decline was discerned for total and constituent IYG concentrations in roots and basal leaves, and constituents showed a mixed pattern of positive and negative correlations with total amount. Vegetative organs thus constitute two compartments relative to glucosinolate metabolism. In above-ground stems and associated cauline leaves, IYG concentrations decline individually and in concert over the growing season, in below-ground rhizomes and associated roots and basal leaves, individual compounds fluctuate in concentration, but in the aggregate do not decline seasonally. Metabolic fluxes of individual glucosinoletes within and between vegetative organs, as well as changes in total concentrations, may influence feeding by herbivores.