Document Detail

Comparative labellar micromorphology of Zygopetalinae (Orchidaceae).
MedLine Citation:
PMID:  21856635     Owner:  NLM     Status:  MEDLINE    
BACKGROUND AND AIMS: Molecular evidence indicates that the Neotropical sub-tribe Zygopetalinae is sister to Maxillariinae. Most members of the latter sub-tribe have deceit pollination strategies, but some species produce rewards such as nectar, pseudopollen, resin and wax, and are pollinated by a range of pollinators that include stingless bees (Meliponini), wasps and hummingbirds. By contrast, relatively little is known about the pollination of Zygopetalinae species. However, some are pollinated by fragrance-gathering, male euglossine bees or employ nectar deceit strategies. The aim of this study is to describe the labellar micromorphology of Zygopetalinae and to compare it with that of Maxillariinae sensu lato (s.l.) as part of an ongoing project to record the range of labellar characters found within the tribe Maxillarieae, and to assess whether these characters represent synapomorphies or homoplasies resulting from similar pollination pressures.
METHODS: The labella of 31 species of Zygopetalinae, including Cryptarrhena R. Br. and representatives of the Zygopetalum, Huntleya and Warrea clades, were examined using light microscopy and scanning electron microscopy, and the range of labellar characters was recorded. These characters were subsequently compared with those of Maxillariinae s.l. which formed the subject of our previous investigations.
KEY RESULTS AND CONCLUSIONS: The labellar micromorphology of Zygopetalinae is less diverse than that of Maxillariinae and does not reflect the currently accepted phylogeny of the former sub-tribe based on molecular studies. Instead, the relative uniformity in labellar micromorphology of Zygopetalinae is probably due to homoplasies resulting from similar pollinator pressures. Labellar trichomes are relatively uncommon in Zygopetalinae, but occur in certain members of both the Zygopetalum and Huntleya clades. Trichomes are unbranched, uniseriate and multicellular with rounded apices, or unbranched and unicellular, with tapering, pointed and flexuose apices. Hitherto, unicellular trichomes of this kind have been observed only for euglossophilous orchid taxa, and the adoption of a relatively limited range of pollination strategies by Zygopetalinae may have resulted in reduced investment in micromorphological labellar characters.
Kevin L Davies; Malgorzata Stpiczynska
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-08-19
Journal Detail:
Title:  Annals of botany     Volume:  108     ISSN:  1095-8290     ISO Abbreviation:  Ann. Bot.     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-09-22     Completed Date:  2012-03-05     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  0372347     Medline TA:  Ann Bot     Country:  England    
Other Details:
Languages:  eng     Pagination:  945-64     Citation Subset:  IM    
School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff , UK.
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MeSH Terms
Bees / physiology
Flowers / anatomy & histology,  ultrastructure*
Microscopy, Electron, Scanning
Orchidaceae / anatomy & histology,  classification,  ultrastructure*
Pollination / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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