13.3 Nonflowering Vascular Plants - PowerPoint PPT Presentation

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13.3 Nonflowering Vascular Plants. Gymnosperms. Nonflowering vascular plants that produce seeds are called gymnosperms. Conebearing trees, such as pine and redwood, are the most common gymnosperms alive today.

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13.3 Nonflowering Vascular Plants

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13 3 nonflowering vascular plants

13.3 Nonflowering Vascular Plants

Gymnosperms


13 3 nonflowering vascular plants

  • Nonflowering vascular plants that produce seeds are called gymnosperms.


13 3 nonflowering vascular plants

  • Conebearing trees, such as pine and redwood, are the most common gymnosperms alive today.


13 3 nonflowering vascular plants

  • Because of their seeds and other adaptations, these plants live and reproduce in places where ferns, horsetails, and club

    mosses cannot.


13 3 nonflowering vascular plants

  • A seed is an adaptation for protecting and nourishing a plant embryo.


13 3 nonflowering vascular plants

  • The embryo inside a seed may remain dormant for a long period of time. Then, when the conditions are right, it can begin growing.


13 3 nonflowering vascular plants

  • Sperm cells develop inside protective cases that can be carried by moving air. (Pollen)


13 3 nonflowering vascular plants

  • As a result, gymnosperms grow in deserts and on dry, windy mountaintops.


13 3 nonflowering vascular plants

  • There are four main groups of gymnosperms alive today.


13 3 nonflowering vascular plants

  • The most common living gymnosperms, the conifers, have needle-shaped leaves and seeds produced in cones.


13 3 nonflowering vascular plants

  • Cycads (SY kadz) are relics of the ancient forests.


13 3 nonflowering vascular plants

  • This gnetophytes (NEE toh FYTS) has long straplike leaves and bears clusters of small cones on short stalks.


13 3 nonflowering vascular plants

  • The ginkgo, also called the maidenhair tree, has fan-shaped leaves and fleshy seeds. Unlike other gymnosperms, the leaves of a ginkgo fall from the tree in autumn.


Life cycle of gymnosperms

Life Cycle of Gymnosperms

Example – Pine Tree


13 3 nonflowering vascular plants

  • The life cycles of gymnosperms differ greatly from the life cycles of ferns, horsetails, and club mosses.


13 3 nonflowering vascular plants

  • The pine tree is the sporophyte generation. It has two types of cones.


13 3 nonflowering vascular plants

  • The large woody cones produce spores that develop into female gametophytes.


13 3 nonflowering vascular plants

  • Smaller, nonwoody cones produce spores that develop into male gametophytes.


13 3 nonflowering vascular plants

  • The female gametophyte remains in the cone. It grows into a many-celled mass in which several egg cells begin to develop.


13 3 nonflowering vascular plants

  • The male gametophyte is packaged into a tiny pollen grain. These are released and carried by the wind.


13 3 nonflowering vascular plants

  • When the wind-borne pollen reaches a cone where the female gametophyte is developing, pollination occurs.


13 3 nonflowering vascular plants

  • The male gametophyte grows a pollen tube through which sperm can reach the egg cell. Fertilization occurs as the sperm and egg fuse. The fertilized egg then develops into an embryo.


13 3 nonflowering vascular plants

  • The embryo is packaged into a seed, along with a food supply.


13 3 nonflowering vascular plants

  • When the seed sprouts and grows into a young sporophyte, the cycle is complete.


13 3 nonflowering vascular plants

  • In this life cycle, the gametophyte generation is very small.

  • For this reason, reproduction in gymnosperms appears to

    involve only one generation producing male and female sex cells.


13 3 nonflowering vascular plants

End


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