What Is the Purpose of a Flower on a Plant?
The sole purpose of a flower is reproduction, and for that purpose, a flower comes armed for the job. Every part of a flower, including scent and beauty, furthers the plant's reproductive strategy. When it blooms, a flower reveals male and/or female parts. The male part is the stamen, which consists of a filament topped by an anther. The anther produces pollen, and within that pollen are sperm. The female part of the flower is a carpal or carpels that might be fused to form a pistil. Within the pistil is an ovary that contains ovules ready for pollination. Some flowers have both male and female parts; other flowers are either male or female.
With sperm and ovule ready, flowers use either wind or creatures to help them get the sperm to the ovule. Small flowers that aren't showy use the wind to spread pollen to other flowers, the pollen landing on stigmas, which sit at the top of pistils. Showy flowers go to greater lengths to reproduce. Petals are colored and have markings to attract insects and animals. The scent, too, draws pollinators to the flower. To ensure that bugs and animals keep returning, flowers produce nectar from glands at the base of their petals. Pollinators, such as bees, birds and bats, pick up pollen as they visit and deposit it to the female stigmas as the pollinators move from flower to flower.
Seeds and Fruit
Once a flower has been successfully pollinated, the sperm joins with the egg. A second sperm fuses with what are called polar nuclei to create food storage tissue, which will feed the developing plant embryo. The whole thing becomes the seed for new life. The ovary that originally contained the ovule, meanwhile, develops into a fruit. Sometimes the ovary wall becomes an outer layer, as is the case, for instance, when a pod is formed. Sometimes part of the flower's tube swells around the ovary, forming a fleshy fruit like an apple. The ovary wall becomes the core.
- Botany; Taylor R. Alexander, R. Will Burnett and Herbert S. Zim; 1970
- Botany online: Features of Flowering Plants - Flowers
- Botany: A Functional Approach; Walter H. Muller; 1970