Flowers

Flowers show enormous diversity - some are large, brightly coloured and showy while others are small and inconspicuous. Yet their common function is that the flower is the organ that provides the means for sexual reproduction to take place in flowering plants (Angiosperms). The male gamete is contained in the pollen grain and the female gamete is contained in the ovule, within the ovary. For fertilisation to occur, the pollen grains must be transferred from an anther (where they are made) to a stigma of a flower of the same species. This process is described as pollination.

Pollen grains do not move by themselves, and thus require an agent to enable pollination to take place. Many flowers are adapted to utilise either wind or insects as the agent that transfers pollen from the anther to a suitable stigma. Transfer by water is rare but a significant number of flowers rely on birds and mammals as the agent for pollen transfer.

Many flowers have developed mechanisms that ensure cross-pollination takes place, so that the flower is not pollinated by pollen from its own anthers on the same plant. This has the advantage of introducing or maintaining more genetic variation within the population, thus avoiding ‘inbreeding’.

The images presented here introduce a small selection from the enormous diversity of flower structure, and illustrate just some of the ways in which floral structure is adapted to its particular mechanism of pollination.


Wind pollination
Insect pollination
Other methods of pollination - by birds, mammals and water