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angiorepro213-page8 - Recall that flower parts are...

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Flowering Plant Reproduction - 8 Flower symmetry does not escape special terms. A flower with radial symmetry is actinomorphic. A flower lacking radial symmetry is zygomorphic. Regular and irregular are comparable terms sometimes used. Bilateral symmetry is genetically controlled, sometimes by a single gene, and has developed independently in many floral lines. Actinomorphic Flower Zygomorphic Flower The attachment of ovules to the ovary walls, called placentation, is also an important. Placentation is not an easy characteristic to see. (The common patterns are axile, along the axis or fusion lines of the ovary, parietal, around the perimeter of the ovary, and free-central. Basal placentation also occurs.) Axile Parietal Free central The attachment position of the ovaries relative to the other floral parts on the receptacle of the flower is also important.
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Unformatted text preview: Recall that flower parts are generally in whorls on the receptacle from the outer calyx to the innermost carpels. A flower in which the calyx is outermost and lowest on the receptacle will have its ovaries attached above or higher on the receptacle. These flowers are called hypogynous (under the ovary), and the ovaries are superior. Some flowers have the calyx surrounding the ovaries, forming a hypanthium or floral cup to which petals and stamens are attached. Such flowers are perigynous (surrounding the ovary). Finally the ovaries can be embedded into the receptacle tissue and the other floral parts (stamens, petals and sepals) are attached above the ovaries on the receptacle. Such flowers are epigynous (on top of the ovary) and the ovaries are inferior. Hypogynous Perigynous Epigynous...
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