EUPHORBIOID INFLORESCENCES FROM THE MIDDLE EOCENE CLAIBORNE FORMATION |
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| Authors: | William L. Crepet Charles P. Daghlian |
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| Affiliation: | 1. Biological Sciences Group U-42, University of Connecticut, Storrs, Connecticut, 06268;2. Department of Botany and Microbiology, 770 Van Vleet Oval, University of Oklahoma, Norman, Oklahoma, 73019 |
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| Abstract: | Inflorescences from the Claiborne Formation of western Tennessee are remarkably similar to those of the tribe Hippomaneae, subfamily Euphorbioideae, of the Euphorbiaceae. The fossil inflorescences are spikes of bract-subtended cymules of at least three florets each. Florets are composed of at least three stamens. Palynological features of the fossils are also shared by the Hippomaneae. Fossil pollen is tricolporate, prolate (26.9 × 20.6 μm; P/E = 1.3), with lalongate pores. Exine structure is tectate columellate with a perforate tectum. The exine is reticulate and the muri are conspicuously striate. These specimens represent the first fossil floral evidence of the Euphorbiaceae. It is surprising that inflorescences of the Hippomaneae so modern in aspect existed in the Middle Eocene, since the tribe is universally considered to be one of the most advanced in the family. |
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