All flowering plants, known as angiosperms, start out as seeds, which holds everything the plant needs to begin life inside of a hard casing. If the seed has enough water and light and the right temperature, the casing will pop open and the seed will sprout and send out roots. This is known as germination.
The first one or two leaves are called cotyledons. They look different than the plant's regular leaves, and are usually small and simple. Their purpose is to emerge quickly and photosynthesize so that the plant can start producing its own nutrition and grow bigger. Depending on the species, the process of germination may take anywhere from one day to several weeks.
As the flowering plant puts out more leaves for photosynthesis, and as the roots spread out further underground to collect water, the plant matures and eventually forms one or more flowers, which contain the building blocks for more seeds. Plants that are classified as annuals will flower and set seed in one year. Biennial plants take two years to mature and produce flowers and seeds. Perennials may take several years to mature, and they may produce several generations of flowers and seeds in their lifetime.
Parts of a Flower
As gardeners, we might only pay attention to the colorful petals or the sweet scent that a flower produces, but there's a lot of action going on underneath that pretty exterior. Like animals, flowers have both male parts and female parts. Many species of angiosperms, including most familiar garden flowers, have male and female parts in same flower.
Other angiosperms, usually trees, have separate male and female flowers on the same plant, and others still have male flowers on one plant and female flowers on another. The female part of the flower is called the ovary, which may not be visible from the outside, although on many flowers you can see a stem (called a style) with a slightly flared end (the stigma) coming out of the ovary in the center of the flower. The male part of the flower is the stamen, of which there may be many. The stamen consists of long, thin filaments with oblong parcels on the end, known as anthers. Anthers carry the pollen, and so they are often distinctively yellow or orange.
Pollination and Seed Formation
Pollination occurs when the pollen from the anthers comes in contact with the stigma. This may be facilitated by the wind or by butterflies, bees, hummingbirds, bats or other animals or insects visiting several flowers for nectar. Most angiosperms cannot pollinate themselves, and require the presence of two or more flowers for pollination. After pollination, the ovules (egg-like structures in the ovary) are fertilized and develop into seeds. Some angiosperms produce just one seed, while others produce dozens in a single flower.
After the flower dies the seeds are dispersed, either by falling to the ground or being eaten by animals and passing through their digestive tract. After dispersal, the seed may be ready to germinate right away, or it may need to rest in a state of dormancy for several weeks, months or even years until it has matured and until conditions are just right for germination. And then the cycle begins again.