Today we looked at the Reproductive organs of flowers, which are large and easy to see in the Lily. The colours and scent of flowers attracts insects which are useful in the dispersion of pollen for reproduction.
Flowers reproduce sexually and have both male and female organs, although to prevent self-fertilisation they mature at different times. In the photo we can see the central female organs (the stigma, style and ovary), surrounded by a number of male anthers (brown). The specimen on the left is from an open flower, and the one on the right is from a bud.
The male sex cells are the pollen and these are small cells that are dispersed by the wind or by insects that come to feed on the sugary nectar that exudes from the female stigma.
The stigma is sticky so that foreign pollen which lands on it will bond. A pollen tube grows down the long style to the ovary which is at the base. Fertilisation takes place when the male sex cell (pollen) fuses with the female sex cell (ovule) becoming a seed.
The flowers' petals drop away as their job is done, but the ovary swells and becomes a fruit to protect the seed as it too falls to the ground. In some species, the swelling is large, colourful and packed with sugar which is attractive as a food source for animals, including birds. When they eat the fruit, the seed will pass unharmed (protected by a seed case) through the digestive system, eventually being egested. In this way the seeds will have been dispersed far from the parent plant and will be able to colonise new areas, thus ensuring the success of the species
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