Morphological Diversification and Taxonomy Among the Varieties of <I>Pedicularis bracteosa</I> Benth. (Orobanchaceae)

Abstract

Multivariate and univariate analyses were used to investigate patterns of floral and foliar morphological diversification among the eight taxonomic varieties of Pedicularis bracteosa (Orobanchaceae). Canonical discriminant analysis supported six varieties but not without considerable morphological overlap. Discrimination was most strongly based upon three floral characters: galea shape, throat length, and calyx tip length; and secondarily on three foliar characters: subtending bract width, longest leaflet width, and longest leaflet length. Analysis of variance on the ratio between calyx length and the length of the connate portion of the calyx did not corroborate a taxonomic difference among all varieties. Because galea shape is associated with specific pollination syndromes that promote reproductive isolation in other Pedicularis species, selection by the different pollinating behaviors of queens versus worker castes of the same species of bumblebees may be driving the diversification of floral morphology. While the taxa are largely allopatric and supported by several strong morphological discriminators, the high degree of morphological overlap among them does not justify their re-ranking above variety. Lack of discrimination between varieties siifolia and canbyi argues for their merger into a single taxon. A revised key to the varieties reflecting the results of this study is presented.