- Flowers have both male and female reproductive organs. Most flowers have both sets of organs, but some flowers have only one or the other. The organs of the male reproductive system are the anthers and the stamen, while the female organs are the stigma, style, ovule and ovary. The stamen holds the anthers and the anthers produce the pollen. The stigma accepts the pollen and the sperm flows down the style into the ovule and then into the ovary.
- Cross-pollination occurs when one plant produces the pollen that fertilizes a completely different plant. When pollen from the same plant fertilizes itself, the process is termed self-pollination. Cross-pollination relies on outside influences to transfer the pollen between two plants of the same type. Cross-pollination sometimes occurs between closely related plants of different species, but this pollination often results in sterile plants or seeds that cannot germinate. A successful cross-pollination of two different species results in a hybrid.
- Animals, wind, water and insects transport pollen from one plant to the next. As animals and insects brush against a plant with mature pollen, the pollen clings to their bodies. When they travel to a second plant, the pollen falls or is trapped by the sticky stigma of the second plant. Wind and water also transport pollen between plants, but these natural occurrences are less reliable than insects and animals. If the pollen the stigma receives is pollen from the same type of plant, a chemical reaction occurs that allows the fertilization process to begin.
- Genetic diversity strengthens a species. If a mutation in the genetic code results in a weakness, or the environment surrounding the plant changes, genetic diversity offers the plant species a chance to adapt. When a plant self-pollinates every time, the new generation is an exact replica of the parent and cannot adapt to the new environment or overcome detrimental mutations.
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