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SEXUAL REPRODUCTION IN AUSTRALIAN FlorA

SEXUAL REPRODUCTION IN AUSTRALIAN FlorA. Introduction. Flowering plants (angiosperms) are stationary, therefore they have developed some reproductive mechanisms to ensure pollination and seed dispersal. Eg flowers (reproductive organs). Pollination.

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SEXUAL REPRODUCTION IN AUSTRALIAN FlorA

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  1. SEXUAL REPRODUCTION IN AUSTRALIAN FlorA

  2. Introduction • Flowering plants (angiosperms) are stationary, therefore they have developed some reproductive mechanisms to ensure pollination and seed dispersal. • Eg flowers (reproductive organs)

  3. Pollination • Pollination is the transfer of the male gametes (pollen) from the male anther to the female stigma in flowering plants. The pollen tube will then grow downwards towards the ovule where fertilisation occurs. • Self pollination - Pollen from anther deposited on own stigma • Cross pollination – Pollen transferred from anther of one plant to stigma of another • What are some adv. and disadv. of each method?

  4. Examples of mechanisms to increases the chance of pollination • Each species has specific adaptations to assist pollination, usually dependant on some other factor or organism • Animals – Attractive, sweet-smelling flowers to attract animals • Wind – No or small flowers. Gametes can have feathery adaptations to catch wind. Usually masses of pollen as success rate lower • Water – Usually no or small flowers. Gametes usually floatable. Usually masses of pollen as success rate lower

  5. Pollination Clip • http://www.youtube.com/watch?v=zR1ilJKE4f0

  6. Examples of Australian Plants  Pollination • Most Australian plants are pollinated by animals, eg birds (honeyeaters, parrots, finches), mammals (possums, rats, bats), or insects (bees, ants, moths, flies). The animals attracted to flower and carry pollen on body.

  7. Examples of Australian plants with mechanisms to increase chance of pollination • Eg 1: Grevillea • Long stigma above stamen to reduce chance of self pollination • Stigma only receptive when all pollen gone from stamen • Eg 2: Moth pollinated paw paw (pale flower, perfume at night)

  8. Seed Dispersal • Seed dispersal is where the plant disperses seeds to the ground, in fruits or by wind or water. • Each new embryo starts to divide and becomes a seed. The ovary may turn into a fruit which protects the seed.

  9. Examples of plants with mechanisms to increase chance of seed dispersal • Winged seeds • Carried by animal inside (tasty fruit  eaten) or outside (sticky) • Prickles on seeds

  10. Explosion mechanism (e.g. some acacias) –

  11. Examples of plants with mechanisms to increase chance of seed dispersal • Wattle seeds have substance eliasome that ants find tasty  Drag them to their nests

  12. Examples of plants with mechanisms to increase chance of seed dispersal • Casuarina – allelochamicals released by parent

  13. Examples of plants with mechanisms to increase chance of seed dispersal • Banksia  seeds retained on plant, fire releases small amount of seeds which have A large energy storage for slow germination • Melaleuca  seeds retained on plant, fire releases large amount of seeds with small energy storage.

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