PlantKingdom213-page10

PlantKingdom213-page10 - Sporophylls and Types of Sporangia...

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Introduction to the Plant Kingdom - 10 Leaf trace patterns and nodes in protostele and siphonstele Dispersal Method All plants disperse to new locations via single-celled spores or by seeds. Spore walls contain sporopollenin, a protective coating that provides protection against decay and dehydration. Seeds are protected by a seed coat, a multicellular layer of thick-walled resistant cells. Sperm transport: H 2 O vs. Pollen Grain All plants must have a way to transport sperm to egg. The "lower" vascular plants rely on water to transport sperm, released from the antheridium, to the archegonium containing the egg. The seed plants protect the sperm within the male gametophyte, the pollen grain, and have a variety of methods of transporting the pollen grain to the female gametophyte, containing the egg.
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Unformatted text preview: Sporophylls and Types of Sporangia A major advance in vascular plants is the development of the sporophyll, a modified leaf that bears sporangia. (Recall that the flower, the reproductive organ of the angiosperms, is a modified shoot system, and the floral parts, including anther (male sporangium) and ovary, enclosing the ovule (female sporangium), are modified leaves.) Sporangia in the vascular plants vary from single sporangia to clusters and groups of sporangia in specialized shoots. Type of sporangia is an important evolutionary distinction in plants. Plants that produce one type of sporangium are called homosporous. Other plants produce two different sporangia, megasporangia and microsporangia and are heterosporous....
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