Seeds grow into plants, which produce flowers. The flowers produce seeds for the next generation. Some plants enclose the seed within a fruit, which may be eaten by animals, who then pass the seeds on at a different location. Other fruits, such as a coconut, protect the seed until it reaches an ideal location. The flowers may not be obvious on all plants, but plants that produce true seeds do so from flowers.
A seed is made up of an outer covering, an embryo and a food source. The embryo, or germ, will grow into a plant given the right moisture level, temperature and soil conditions. Plants have adapted to growing environments all over the earth, from the high Arctic tundra to deserts to the ocean floor, and under the right conditions, they all produce seeds.
Once the right moisture level and temperature is achieved, germination begins. The seed coat is softened and moisture stimulates the embryo to begin growing. Cell division takes place as the embryo puts out the beginning of a root. What happens next depends on the type of seed.
A monocotyledon seed sends up a shoot at the same time it anchors itself with roots to draw moisture and nutrients from the soil. The first leaf breaks through the soil and, given a source of light, will begin photosynthesizing food. The seed's stored food is quickly expended during this short process, and the plant will require light, moisture and soil nutrients to survive past this point.
A dicotyledon seed is easily differentiated from the monocotyledon by its two seed leaves called cotyledons. As the root extends through cell division, the seed is pushed upward through the soil. The seed coat is discarded as the cotyledons open and photosynthesis begins.
The plant grows, using the energy it produces to add leaves, stems and roots. The seed it grew from is long gone and the plant must grow and survive until it reaches maturity. Annual plants reach maturity in a single growing season. Some biennial plants require two seasons. Perennials live longer, taking two or more years to mature. Trees typically take years to mature before they produce flowers.
Once the plant reaches maturity, it will produce flowers if the right conditions exist. For annuals or biennials, this is the end of their life. They will produce seed for the next generation and die. Some do this over most of the growing season, others only at the end of it.
Certain plants, as in some species of bamboo, may produce flowers and seeds only if the plant is dying, using all its energy to grow seeds and ensure survival.
Plant flowers have two parts, a stigma and a stamen. Plants that produce flowers with both parts are called perfect flowers, which may or may not be capable of self-fertilizing. Other plants produce male and female flowers that have only one part.
The male stamens produce pollen at the anther, atop the filament. The pollen is transferred to the stigma, or female portion, via insects, wind or self-pollination that occurs when the anthers brush the stigma. The stigma transfers pollen grains down to the ovary, where it combines with the ovum to produce new seeds, completing the cycle of seed to plant to flower.