Developmental and Structural Section
Rudall, Paula, J. , Cunniff, Jennifer , Box, Mathew S. , Strange, Amy , Bateman, Richard M .
Fascicles and filamentous structures: comparative ontogeny of morphological novelties in Triuridaceae.
FLOWERS with multiple (more than three) carpels that remain completely free from each other (a condition here termed polyapocarpy), are common in magnoliids and the ANITA grade but rare in monocots, except some Alismatales and Pandanales. The phylogenetic position of Alismatales (as putative sister to all other monocots except Acorus) has prompted some authors to regard polyapocarpy as the primitive monocot condition, representing a plesiomorphic feature shared with some magnoliids. Conversely, other authors have highlighted the differences between flowers of alismatids and magnoliids, inferring that polyapocarpy is derived in monocots. Species of the mycoheterotrophic family Triuridaceae (formerly considered allied with Alismatales, but now placed in Pandanales) possess numerous (6–50) free carpels in female or bisexual flowers. Here we focus on a comparative ontogenetic investigation across a wide taxonomic range within Triuridaceae, using a morphological analysis of Pandanales as a phylogenetic framework. We examine whether floral ontogeny helps to resolve the systematics of Triuridaceae and the homologies of their floral structures. In particular we address the ambiguous inflorescence–flower boundary in triurids and the notorious inside-out floral construction in the Mexican triurid genus Lacandonia. We compare the polyapocarpous condition in Pandanales and Alismatales, using representatives from Alismataceae. A further goal is to examine the homologies of the novel filamentous structures that occur on different parts of the flower in some Triuridaceae. Comparative ontogenetic data are potentially important in establishing homologies, but they are difficult to obtain for Triuridaceae, because individuals are minute and ephemeral, and populations are restricted, each typically containing fewer than 250 individuals. Previous studies of floral ontogeny in the family are limited to a relatively restricted taxonomic sampling. Our broader taxonomic sampling allows more rigorous evaluation of some of the unusual floral structures of this family across all three tribes of Triuridaceae (Kupeaeae, Triurideae, and Sciaphileae).
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1 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond, Surrey, TW9 3AB, United Kingdom
2 - University of Sheffield, Dept of Animal and Plant Sciences, Sheffield, S10 2TN, United Kingdom
3 - Imperial College, South Kensington Campus, London, SW7 2AZ, United Kingdom
4 - John Innes Centre, Cell and Developmental Biology, Norwich, NR4 7UH, United Kingdom
5 - Natural History Museum, Department of Botany, Cromwell Road, London, SW7 5BD, England
Presentation Type: Oral Paper:Papers for Sections
Location: 303/Bell Memorial Union
Date: Wednesday, August 2nd, 2006
Time: 10:15 AM