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Anatomie comparée des palmiers - Identification assistée par ordinateur, applications en paléobotanique et en archéobotanique

Abstract : The oldest fossil palm stem (Arecaceae Bercht. & J.Presl) were recovered from the Cretaceous of Anjou (Turonien). Because of the absence of referential on stem anatomy, almost no identification has been done below the family level. In this study, from the analysis of the anatomy of palm stems, I present a descriptive system in order to make identifications in paleobotany and archaeobotany. All the five subfamilies were sampled (Calamoideae, Nypoideae, Coryphoideae, Ceroxyloideae, Arecoideae) and 154 specimens belonging to 81 genera are analyzed. Coryphoideae are particularly studied (28/46 genres) with a detailed description of each tribe of this subfamily. These descriptions are implanted in Xper2, an expert system (http://www.infosyslab.fr/Palm-ID/) that allows interactive identifications at the sub-familial, tribal or generic level with the help of 32 descriptors and 108 states. The results of this study show that it is possible to identify the five subfamilies and most of the tribes of the Coryphoideae from some specific anatomical structures (fibrovascular bundles, number of vessel elements, ground parenchyma organization, general distribution of the fibrovascular bundles through the transverse section). The different growth patterns are redefined from two mechanisms: the sustained growth of ground parenchyma and the centrifugal differentiation of the fibrous part of vascular bundles. This centrifugal differentiation is the result of the formation of new fibers at the periphery of the fibrous part and is not observed in Coryphoideae (except in Caryoteae). The results of this anatomical survey have implication in archaeology and two examples are presented: (i) the identification of charcoal palms (Saudi Arabia, iind century BCE), (ii) the identification of a fishing net made from palm fibres (Pakistan, ivth millennium BCE). The study of some unidentified Palmoxylon from two sites in South-Eastern France (Vallé d'Apt, Rupelian and Castellane, Tortonian) provides evidences that these fossil stems belong to the Cryosophileae. Today, this tribe is endemic to the American continent and it is the first fossil record of this tribe outside America. As it is possible to identify more precisely the fossil palm stem, it will improve the palm evolutionary history knowledge and provide additional information on dating divergence times in phylogenies.
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Submitted on : Wednesday, February 26, 2014 - 3:26:03 PM
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  • HAL Id : tel-00951106, version 1

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Romain Thomas. Anatomie comparée des palmiers - Identification assistée par ordinateur, applications en paléobotanique et en archéobotanique. Botanique. Museum national d'histoire naturelle - MNHN PARIS, 2011. Français. ⟨tel-00951106⟩

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