Seasonal variation in the glucosinolate content of North American Brassica nigra and Dentaria species

Concentrations of glucosinolates in the leaves of the woodland cruciferous herbs Dentaria laciniata, D. diphylla and D. maxima declined during the 1974 growing season but generally equalled or exceeded the levels found in the foliage of Brassica nigra, a crucifer of neighbouring open habitats. The superior quality of Dentaria foliage for certain crucifer-feeding insects does not seem to result from an unusually low concentration of glucosinolates. The qualitative and quantitative compositions of glucosinolates in the leaves and rhizomes of D. maxima were found to be intermediate between the corresponding values for D. laciniata and D. diphylla. This finding is consistent with a hybrid origin for D. maxima.