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Abstract Detail

Developmental and Structural Section

Freudenstein, John [1], Broe, Michael [1].

Perianth structure in leafless Ericaceae – sepals or bracts? .

The reduction that occurs in vegetative structures in leafless plants can make homology decisions difficult. Such is the case with the perianth in Hypopithys and Monotropa (Monotropoideae). The identity of the “outer whorl” of the flower in these genera has been the subject of longstanding debate, some arguing that they are bracts “becoming” sepals and others claiming that they are degenerate true sepals. We examined floral development at several stages, compared the morphology among the recently revised species of these genera, and related the morphologies to those of close relatives based on our recent phylogenetic analysis of the group. We conclude that neither Hypopithys nor Monotropa has true sepals but that these structures are bracts, based on the arrangement of these structures, the fact that they do not form a true whorl, and the presence of rudimentary buds in their axils. Recognition of the diversity of species within Hypopithys has been especially important in this study, since they have differing expressions of the bracts and form series of intermediates that help to link what otherwise appear to be ambiguous morphologies. These perianth features and associated infloresence structures are interpreted in the greater phylogenetic context of the subfamily.

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1 - Ohio State University Herbarium, Evolution, Ecology and Organismal Biology, 1315 Kinnear Road, Columbus, OH, 43212, USA

floral development

Presentation Type: Oral Paper:Papers for Sections
Session: 69
Location: Salon 11/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 2:30 PM
Number: 69005
Abstract ID:1146
Candidate for Awards:None

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