Biology-gnetophyta

Biology-gnetophyta - Sonoma State University Biology 121...

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Sonoma State University, Biology 121 Kate Parrott Phylum Gnetophyta Characteristics of the group : The phylum Gnetophtya belongs to the plant kingdom and is considered a type of gymnosperm (seed plant) which is known as woody plants. Gnetophyta consists of one class of living plants (Gnetopsida), which contains three extant families: Gnetaceae, Ephedraceae, and Welwitschiaceae. The Gnetophyta phylum differs from other gymnosperms because they contain vessel elements very alike to angiosperms (flowering plants). Vessel elements refer to cell tissues found in the xylem, and are typically only located in angiosperms and not gymnosperms. As for reproductive characteristics, females are found with one erect ovule, the nucellus enclosed in 2 or 3 coats, and a micropyle projecting as a long tube. Male cones are fertilized by 2 male nuclei through pollen tubes. This is the only gymnosperm phylum where double fertilization has been recorded, which (similar characteristic to angiosperms, yet they are not necessarily homologous). Insect pollination is also known to occur through cone discharge. Morphological data suggests that the plants in the Gntophyta phylum are closer to
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This note was uploaded on 04/27/2008 for the course BIO 121 taught by Professor Janousek during the Spring '08 term at Sonoma.

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