Relationships and character transformation in Pyroloideae (Ericaceae) based on ITS sequences, morphology, and development

The small subfamily Pyroloideae, comprising four genera, is unusual in Ericaceae because of its nearly herbaceous habit, largely free petals, and tendencies toward leaflessness. A surprising number of hypotheses exist with respect to the relationships among these genera. Parsimony analysis of 23 morphological characters gave a pattern that is largely congruent with that obtained from analysis of ITS sequences. Two sister clades of monophyletic/monospecific genera are resolved-Chimaphila + Moneses and Orthilia + Pyrola. Relationships among three species of Chimaphila are not clearly resolved. Some structure is present within Pyrola with two strongly supported clades (P. picta + P. aphylla + P. chlorantha and P. elliptica + I! minor). The placement of P. minor is unsuspected; most past classifications have segregated it from other Pyrola due to its short, straight style (as opposed to a longer, curved style). Developmental study reveals that the style terminates elongation early, so that in fact it is not clear which style orientation is present. The overall bud-like nature of the flower in I! minor further suggests a juvenile morphology relative to other Pyrola. The developmental information, in combination with its position on the cladogram, indicates a paedomorphic origin for the floral morphology of P. minor.