According to Biosciences for Farming in Africa, sexual reproduction in plants occurs when pollen from a plant's stamen reaches the stigma of a flower. The pollen contains sperm cells while the stigma holds the corresponding eggs. When the two meet, the sperm cells fertilize the egg, creating an embryonic seed that later germinates into a new plant.
Pollination is the process that moves the pollen from the stamen to the stigma, and it can occur in a variety of different ways.
Some plants are wind-pollinated, relying on air currents to spread the genetic material between different plants. These plants typically do not have elaborate flowers and spread their pollen early in their life cycle since fully mature leaves might block or trap some of the pollen.
Other plants rely on water pollination, allowing rain, dew or bodies of water to carry pollen to other members of the species.
Many plants rely on insect pollinators to carry the pollen from one plant to the next. Bees are one of the most common pollinators, but many different insects can provide this valuable service to the plant kingdom. Plants that rely on insect pollinators often evolve elaborate flowers filled with sweet-smelling nectar in order to attract the insects and facilitate sexual reproduction.