Angiosperms - matures into a fruit, which aids in the...

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Angiosperms Angiosperms are typically divided into two classes: monocots (including grasses, grains, and spring-flowering bulbs such as daffodils) and dicots (including oaks, elms, sunflowers, and roses). As discussed in Xylem and Phloem , angiosperms have a vascular advantage over gymnosperms. The vessel elements in their vascular tissue, which evolved from the tracheids found in conifers, are more specialized for conducting fluids. In addition, fibers within angiosperm xylem give added support to the plant structure. Another positive adaptation that is exclusive to angiosperms is the flower, which attracts insects and thus facilitates the transfer of pollen. Flowers, the reproductive structures of angiosperms, take the place of gymnosperm cones. Furthermore, while the ovules of gymnosperms are exposed on the surface of the cone), angiosperm seeds (which develop from ovules) are enclosed within an ovary. This ovary later
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Unformatted text preview: matures into a fruit, which aids in the dispersal of the seeds (through animals or wind) and protects the seeds from drying out. Much of the angiosperm life cycle resembles that of gymnosperms. The sporophyte stage dominates, and the gametophytes are even smaller than those of gymnosperms. The mature diploid plant produces male and female haploid spores through heterospory, which gives rise to single-sex gametophytes, which in term produce gametes. These gametes, through either self-pollination or cross-pollination, join to form a diploid zygote that eventually becomes a seed for a new angiosperm. For more information on the life cycles of angiosperms see Alternation of Generations . The parts of the flower that contribute to reproduction are discussed in Plant Structures ; the process of fertilization is covered in Plant Life Cycle,...
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