O'Leary, Elizabeth , Manchester, Steven R. .
Fin-winged fruits in the fossil record and implications for recognition of Combretaceae in the Tertiary of North America.
A great diversity of genera have developed fruits adapted to “blowing in the wind.” Although the general form of the wind-dispersed fruits may be similar between genera of different families, they can be distinguished by careful attention to morphological and anatomical characters including number and shape of wings, wing venation, gynoecial structure, the presence of perianth parts, peduncle, and epidermal features such as trichomes. Identification of winged fruits is particularly useful in instances where the whole plant may be inaccessible or unavailable, for example in forest floor inventories, or in assessing fossil assemblages.
Unfortunately, details of fruit morphology are often overlooked in the descriptions of genera and species. Terminology for fruit types is not consistent, and winged fruits are often lumped together as “samaras” or conversely broken into many different types which are difficult to distinguish. One common morphotype is the fin winged fruit (often described as a “tumbler” when describing dispersal). Examples of this morphotype can be found in genera including Halesia, Rumex, Gouania, and Combretum.
The Combretaceae has many species in the genera Combretum and Terminalia with this type of winged fruit. Today, this family is found in tropical and subtropical areas, but Combretaceous fossils have been described from regions that are now temperate, including localities in North America. Most of the fossils previously attributed to the Combretaceae are leaves; however the leaf architectural characters of this family (entire-margined pinnately veined leaves) cannot be distinguished with certainty from those of many other families. We reexamine the North American fossil record of fin-winged fruits and reassess previous reports of Combretaceous fruits from the Tertiary of North America to gain insights into the phytogeographic history of this family.
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1 - University of Florida, Botany, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
2 - Florida Museum of Natural History, Dickinson Hall, P.O. Box 117800, Gainesville, Florida, 32611, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 3:30 PM