The systematic position of the genus Rhinanthus (Scrophulariaceae) in North America

Abstract

North American plants of the genus Rhinanthus are generally designated as R. crista-galli L., or sometimes as R. borealis (Sterneck) Druce or R. stenophyllus (Schur) Druce. The name R. crista-galli, however, has been declared a nomen dubium, and in Europe the corresponding plant is now known as R. minor L. We have compared North American and European material of Rhinanthus on the basis of general morphology, soluble seed proteins, and seed morphology. General morphology proved to be a poor guide to interpopulation variation in these highly plastic plants, even when aided by numerical methods. Seed protein banding has already been shown to be an extremely valuable and stable guide to taxonomy at or below the species level. We have demonstrated four distinct protein banding types in our material: a southeastern Canadian type (S), a northern Canadian type (N), a European type (E), and a hybrid between S and N. Subsequently, we have attempted to allocate populations to the correct seed protein type on the basis of seed morphology alone using discriminant analysis. This allocation is correct in the great majority of cases. We propose that both the southern Canadian and European types be designated as R. minor var. minor (although the two types can in some cases be distinguished on the basis of seed proteins), and that the northern Canadian type be called R. minor var. borealis. We also present a survey of the seed morphological characters that serves to distinguish the two varieties.