Plants make flowers so they can make seeds that produce new plants. Flowers come in many sizes and varieties. Some are large and bright to attract insects, birds and animals for pollination, while others are nearly invisible because they rely on wind or other methods to reproduce. But all flowers have the same basic structure, including the part of the flower that holds the nectar.
Nectar is a sugary liquid formed by glands called nectaries at the base of flower petals in the carpal, or female organ, of a flower. Besides carbohydrates such as sucrose, glucose and fructose, nectar also contains proteins, amino acids, vitamins, minerals, flavonoids, organic acids, lipids, antioxidants, alkaloids and oils. The amounts of these substances vary in different plants.
Sepals and Petals
The flower parts we can see include the sepals and petals. Petals attract insects to a plant so the insects can carry pollen to other plants. Sepals are the parts, usually green, that protect the petals before they open. In some plants, the sepals also protect and hold together petals after they open. The nectaries are also protected by the sepals.
Female parts of a flower have a carpal, which includes a pistil that produces seeds, In the pistil are a stigma that holds pollen grains, a style that pollen grains grow through, and an ovary where seeds wait for pollen and grow after pollination. This is the part of the plant that holds nectar.
The stamen, which is the male part of the flower, includes an anther that holds pollen grains as they form and a filament that supports the anther. Pollen is a fine, powdery dust, usually yellow.
Petals attract insects with the promise of nectar, the sugary liquid found inside the flower carpal at the base of the petals. When insects crawl inside to get to the nectar, pollen grains brush onto the insects, who take it with them to the next flower that offers nectar. The pollen sticks to the stigma of the next flower, and a tube develops. When the tube reaches the young seeds, or ovules, inside the ovary, sperm in the pollen enters the tube and fertilizes the seeds. This process only happens when the pollen is spread to flowers of the same kind.
Some nectar contains toxins that act as defense mechanisms. This nectar is produced in extrafloral nectaries, usually on the stems or edges of leaves. Some toxins protect flowers from fungus while other nectar contains toxins to repel organisms that take the nectar without helping in reproduction. Some extrafloral nectaries attract insects that kill plant pests.