Systematics/Phytogeography / Taxonomie/ Section
Manchester, Steven R. , O'Leary, Elizabeth .
Phylogenetic distribution of fin-winged fruits and the identification of fossils.
Winged fruits are commonly preserved as compression and impression fossils in lake sediments along with leaf remains. However, the taxonomic affinities of fossil winged fruits often remain uncertain due to incomplete comparative data on the morphology of extant taxa. We conducted a worldwide survey of extant fin-winged fruits as an aid for the identification of fossil specimens. Fin-winged fruit have two or more longitudinal wings aligned with the longitudinal axis like the feathers of an arrow, as exemplified by Combretum, Halesia, and Ptelea. Such fruits vary in dispersal mode from samaroid, in which the fruit itself is the ultimate disseminule, to schizocarps dispersing two or more mericarps, to capsules releasing multiple seeds. At least 40 families and more than 120 genera are known to possess fin-winged fruits. The condition is most prevalent among Eudicots, but occurs occasionally in Magnoliids (Hernandiaceae: Illigera), and Monocots (Burmannia Dioscorea, Herreria). Although convergent in general form, the fruits of these different genera can be distinguished by details of the wing number, texture, shape and venation, along with characters of persistent floral parts and dehiscence mode. Families having fin-winged fruits and epigynous perianth include Aizoaceae (Tetragonia), Apiaceae, Araliaceae, Begoniaceae Burmanniaceae, Combretaceae, Cucurbitaceae, Dioscoreaceae, Haloragaceae, Hernandiaceae, Lecythidiaceae (Petersianthus), Lophopyxidaceae, Loranthaceae (Nuytsia), and Styracaceae. Families with fin-winged fruits and hypogynous perianth include Brassicaceae, Celastraceae, Cunnoniaceae (Gillbeea), Cyrillaceae (Cliftonia), Fabaceae, Malvaceae, Melianthaceae, Nyctaginaceae, Pedaliaceae, Polygalaceae, Phyllanthaceae (Hymenocardia), Polygonaceae, Rhamnaceae, Sapindaceae, Simaroubaceae (Soulamea), Trigoniaceae, Zygophyllaceae. This survey has facilitated the identification of fossil fruits of Combretum in the Paleocene of North Dakota, Tetrapterocarpon in the Oligocene of England and France, Staphylea in the Oligocene of western Montana, and Halesia in the Miocene of Idaho and has led to the conclusion that several taxa of fin-winged fruits from the Tertiary of western North America represent extinct genera.
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1 - Florida Museum of Natural History, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611, USA
2 - University of Florida, Botany, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM