Origin and evolution of angiosperms pdf
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The Origin and Evolution of the Angiosperm Carpel
Growing evidence of morphological diversity in angiosperm flowers, seeds and pollen from the mid Cretaceous and the presence of derived lineages from increasingly older geological deposits both imply that the timing of early angiosperm cladogenesis is older than fossil-based estimates have indicated. An alternative to fossils for calibrating the phylogeny comes from divergence in DNA sequence data. Here, angiosperm divergence times are estimated using non-parametric rate smoothing and a three-gene dataset covering ca. The results provide an initial hypothesis of angiosperm diversification times. Using an internal calibration point, an independent evaluation of angiosperm and eudicot origins is performed.
The angiosperm carpel is one of the defining characteristics of flowering plants. Carpels are unique to angiosperms and are found in all of its members. Yet, due to the distinctive structure and function of carpels, deducing homologies among carpels and other seed-plant organs has been difficult. Progress in understanding carpel homologies and evolution is being made in a number of directions. Homologies, as well as transformations between them, have been proposed among angiosperms and other seed plants.