Chapter 30 - Plant Diversity II - the Evolution of Seed Plants

This preview shows page 1 - 3 out of 5 pages.

Chapter 30 – Plant Diversity II: The Evolution of Seed Plants30.1 – Seeds and pollen grains are key adaptations for life on landIn addition to seeds, the following are common to all seed plantsoReduced gametophytesoHeterosporyoOvulesoPollenoSeeds Advantages of reduced gametophytesoThe gametophytes of seed plants develop within the walls of spores that are retained within tissues of the parent sporophyteoTherefore, we do not see the gametophyte generation in seeded plantsHeterospory: the rule among seed plantsoThe ancestors of seed plants were likely homosporous, while seed plants are heterosporousHomosporous – same spore; produces EITHER male spores or female sporesHeterospores – different spore; produce BOTH male and female sporesoMegasporangiaproduce megaspores that give rise to female gametophytesEgg  female  largest cell  megaoMicrosporangiaproduce microspores that give rise to male gametophytesSperm  male  small  microOvules and production of eggsoAn ovuleconsists of a megasporangium, or megaspore, and one or more protective integumentsPollen and production of spermoMicrospores develop into pollen grains, which contain the male gametophytesoPollination is the transfer of pollen to the part of a seed plant containing the ovulesoPollen eliminates the need for a film of water and can be dispersed great distances by air of animalsoPollen grains do not need flagella because they can be carried by wind or other organismsoIf a pollen grain germinates, it gives rise to a pollen tube that discharges sperm into the female gametophyte within the ovuleThe evolutionary advantage of seedsoA seed develops from the whole ovuleoA seed is a sporophyte embryo, along with its food supply, packaged in a protective coat
oSeeds provide some evolutionary advantages over spores

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 5 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Spring
Professor
zambito
Tags
Plants, Evolution, Flowering plant, Pollen

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture