Monday, 19 November 2012

2.3 Plants Reproduce

Why plants need to reproduce?

1) Plants reproduce to make new plant.
2) They reproduce to ensure the survival of their species.
3) If plants do not reproduce and become extinct, life on Earth will be very different.
    (a) Animals that depend on plants for their food supply will not be able to survive. These animals eat only plants and will be die of hunger if there are no more plants.
    (b) Without plants, humans will not be able to survive on Earth.
4) The Earth will become very hot and the amout of carbon dioxide in the air will increase.


Reproduction in plants

How do plants reproduce?
They reproduce through...
  1. Seeds
  2. Suckers
  3. Stem cuttings
  4. Spores
  5. Leaves
  6. Underground stems

1) Reproduction through seeds.
    (a) The flowers of flowering plants develop into fruits that contain seeds. When these seeds are planted, they will geminate into seedlings that grow into young plants.

                A papaya tree reproduces through seeds.

    (b) Some plants produce many seeds in a fruit such as watermelon, papaya, maize and balsam.
    (c) Plants like mango and rambutan produce only one seed in each fruit.

       



2)  Reproduction through suckers.
    (a) Suckers are new shoots that grow from the buds at the base of the stems of parent plants. These young plants grow around the parent plants.
    (b) The pineapple, bamboo and banana tree are examples of plants that reproduce through suckers.








 Banana tree












Sucker of banana tree

 


Pineapple














Sucker of pineapple






3) Reproduction through stem cuttings.
     (a) Plants that reproduce through stem cutting are as follow.

            










Tapioca


 (b) When the stem cuttings of these plants are planted in the soil, the buds on the stem cuttings will grow into new plants.
  








   sugar cane











bud sugar cane








4) Reproduction through spores.
    (a) Non-flowering plants do not produce seeds.
    (b) Non- flowering plants such as ferns and mosses reproduce through spores.




Mushroom











Mushroom spore










Fern







Fern spores






  • The spores are light and can be carried by wind.
  • The spores land on moist places and grow into new plants.
5) Reproduction through leaves.
    (a) The aloe vera, African violet, bryophyllum and begonia are plants that reproduce through leaves.
    (b) The leaves of these plants are usually thick and buds grow from them.
            





Bryophyllum and young plants



              

 When a bryophyllum leaf drops to the ground new shoots at the edge of the leaf will grow
                    into new plants.


6) Reproduction through underground stems.
    (a) Plants such as the onion, potato, ginger and water lily grow from underground stems.
    (b) Underground stems store food for these plants.
    (c) Buds found on the underground stems below the soil surface grow into young shoots and roots.
 

                                       The underground stems of these plants can be eaten.

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