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Abstract Detail

Systematics Section / ASPT

Green, W. A. [1], Little, Stefan A. [2].

Leaf characters across families and orders of angiosperms: testing the utility of Compendium Index Categories for taxonomic identification and phylogenetic analysis of modern cleared leaves.

The Yale Peabody Museum holdings of the National Cleared Leaf Collection consist of about 6000 accessioned leaf specimens of extant taxa. Leaves are cleared, stained, and mounted between glass slides for easy examination by transmitted light microscopy. We scored each specimen for a Compendium Index Category (CIC), morphological categories designed for classification of fossil plant remains. CICs provide a rapid, straightforward scoring system, and CIC attributions are known for many fossils. Does knowing the CIC in which an unknown modern leaf falls assist identifying it and placing it in its correct phylogenetic position? Using heatmaps as tabular keys for taxonomic identification (independent of phylogenetic relationships), we show that an unknown leaf will seldom be attributable to a single family or order based on its CIC alone. However, CICs do prove useful for narrowing a broad search for a specimen's relatives to likely higher taxonomic groups. A mapping of CIC characters onto known phylogenetic trees reveals some evolutionary patterns, but since each CIC can represent up to 10 leaf characters, we argue that the CICs should be redesigned to represent variation in angiosperm leaf form better. This will allow investigation of the systematic signal and environmental plasticity in leaves in more detail while retaining the advantages of rapidity and convenience provided by the CICs.

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1 - Yale University, Department of Geology & Geophysics, Yale Station, P.O. Box 208109, New Haven, Connecticut, 06520-8109, USA
2 - Pennsylvania State University, Department of Geosciences, 510 Deike Building, University Park, PA, 16802-2714, USA

leaf morphology
leaf architecture
character evolution
tabular keys
Compendium Index Categories.

Presentation Type: Oral Paper:Papers for Sections
Session: CP24
Location: Continental C/Hilton
Date: Tuesday, July 10th, 2007
Time: 9:00 AM
Number: CP24005
Abstract ID:2165

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