Lophate sculpturing of Vernonieae (Compositae) pollen |
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| Institution: | 1. Oklahoma Biological Survey and Department of Botany–Microbiology, 770 Van Vleet Oval, Room 135, University of Oklahoma, Norman, OK 73019-6131, USA;2. Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, GA 31061, USA;3. Samuel Roberts Noble Microscopy Laboratory, University of Oklahoma, Norman, OK, 73019, USA;1. Botanic Institute of Barcelona (IBB-CSIC-ICUB), Pg. del Migdia, s/n, ES-08038 Barcelona, Spain;2. Department of Ecology & Systematics, Faculty of Biology, National & Kapodistrian University of Athens, Panepistimiopolis, GR-15784 Athens, Greece;1. Department of Forest Sciences, University of Lavras, UFLA, 37200-000, Lavras, MG, Brazil;2. Department of General Biology, Biotechnology Postgraduate Program, University of Montes Claros e UNIMONTES, 39401-089, Montes Claros, MG, Brazil;3. Department of Forest Sciences, University of Lavras e UFLA, 37200-000, Lavras, MG, Brazil;1. Dipartimento di Studi Umanistici, Università degli Studi di Ferrara, Corso Ercole I d''Este 32, 44121, Ferrara, Italy;2. UMR 5608 TRACES, Université Toulouse Jean Jaurès, Maison de la Recherche, 5 allées A. Machado, 31058, Toulouse Cedex 9, France;3. McCord Centre for Historic and Cultural Landscapes, School of History, Classics and Archaeology, Newcastle University, Armstrong Building, Queen Victoria Road, Newcastle upon Tyne, NE1 7RU, UK;4. Dipartimento di Lettere e Filosofia, Università degli Studi di Trento, Via T. Gar 14, 38122, Trento, Italy;5. Via Maraga 11, 32100, Belluno, Italy;6. Associazione Amici del Museo di Belluno, Via San Francesco 64, 32100 Belluno, Italy;1. University of Göttingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Palynology and Climate Dynamics, Germany;2. Instituto Chico Mendes de Conservação de Biodiversidade (ICMBio), Brazil;3. CNPq-Brazil Scholarship, Brazil;4. USDA Forest Service, Pacific Southwest Region, Vallejo, California, USA;5. Department of Environmental Science and Policy, University of California, Davis, California, USA |
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| Abstract: | Vernonieae (Compositae) taxa Vernonia and Elephantopus were examined by scanning (SEM) and by transmission electron microscopy (TEM). All pollen grains of Vernonia have a subechinolophate sculpturing consisting of a wrinkled net-like ektexine delineating a system of thickened and randomly meandering ridges and corresponding valleys. Ektexine on the ridges radiates from near mid-regions of massive, individual columellae that terminate in sharp spines approximately 4.5 μm above the ektexine surface. Less massive secondary columellae without apical protrusions support the ektexine net in the spine areas. In the valleys, the ektexine is markedly depressed. Removal of the net by freeze-fracture exposes an exine surface that is clearly imprinted with distinctive lophate features. Elephantopus pollen is echinolophate and extends the morphological range for this little studied genus. Lophae are the thickened equivalents of ektexine tecta and represent the highly anastomosing and intertwined rod-like elements of forked distal parts of densely clumped, massive columellae. Lophae surfaces contain rare punctations that are randomly scattered among blunt spinules ranging from approximately 0.3 to 1.5 μm in height. It is clear that only one sculpture pattern, lophate, characterizes Vernonieae pollen and that it embraces two forms, subechinolophate and lophate. Of the two structural patterns in the Compositae, caveate and noncaveate, subechinolophate sculptured Vernonia pollen is noncaveate. Elephantopus pollen is also noncaveate but more generalized than Vernonia. |
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