Invasive tapetum and tricelled pollen inAmbrosia trifida (Asteraceae,tribeHeliantheae) |
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Authors: | N R Lersten J D Curtis |
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Institution: | (1) Department of Botany, Iowa State University, 50011 Ames, IA, USA;(2) Department of Biology, University of Wisconsin, Stevens Point, Wisconsin, USA |
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Abstract: | Staminate flowers of giant ragweed,Ambrosia trifida L. (Asteraceae, tribeHeliantheae, subtribeAmbrosiinae) were processed into resin and sectioned 1–2 µm thick. The invasive (amoeboid) anther tapetum remains parietal until microspores are released from tetrads, then it swells and invades the locule, merging gradually into a single protoplast that flows among the microspores. After the tapetal membrane ruptures at late microspore stage, tapetal debris fills the locule, then disappears as pollen matures. Pollen becomes tricelled before anthesis. The two sperm cell nuclei are slender and wormlike. The present report supports the two generalizations that invasive tapetum and tricelled pollen are attributes of theAsteraceae. |
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Keywords: | Angiosperms Asteraceae Heliantheae Ambrosia Anther crystals pollen sperm cells tapetum |
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