Seeds, which come in various sizes and shapes, are all designed to grow into plants. According to Clinton Community College, a seed has a protective coat that contains the sporophyte embryo and food for that embryo. A seed's embryo can remain dormant for years; it's only when conditions are favorable that the embryo starts to grow, beginning the first step of a seed plant's life cycle.
Seed plants, also known as spermatophytes, are plants that begin life as seeds. They're some of the most vital organisms found on earth, notes the University Of California Museum Of Paleontology. Plants that produce seeds are more familiar to most people than seedless plants such as mosses, horsetails and liverworts, which are smaller and considered less significant. A seed-plant cycle is the entire life span of a plant.
A seed is sown in the ground, and when it starts to receive water and the correct temperature, a stem and root begin to form, notes the Schools @ Look4 website. As the stem pushes up, a sprout develops and branches appear. As this occurs, the root pushes downward to absorb water and nutrients from the soil, so the new plant can grow. Then leaves form on the plant stem and the plant is now a seedling. After the seedling becomes an adult plant, it develops seeds from which new plants can grow as the next generation continues the life cycle.
Seed plants are either annuals, biennials or perennials, based on their life cycle. Annuals finish a life cycle in one year or growing season. Biennials need two years to complete their life cycles. They produce leaves and food storage organs the first season. Then, after overwintering, they grow flowers, seeds and fruit the next season.
Perennials, which live two years or more, are either woody or herbaceous perennials. While woody perennials have woody stems and can survive winter temperatures, herbaceous perennials have non-woody, soft stems that die back in the soil during winter in cold climates.
Annuals can often grow year-round in warm climates such as South Florida but can't survive growing throughout the year in colder regions. On the other hand, perennials generally prefer cooler climates, notes the University of Vermont. They bloom each year and undergo foliage death for the remainder of the time, notes Different Kinds of Plants.com. These plants, known as deciduous perennials, can't regrow because their stem tissue already exists.
Vernalizing a biennial seed before it's planted can considerably reduce its life cycle, says Different Kinds of Plants.com. This involves treating a germinating seed with cool temperatures to induce flowering at a preferred time. Rather than taking two years to finish a life cycle, a vernalized biennial seed can take only three months to complete its cycle. Although early vernalization can be beneficial for commercial farmers when growing plants eaten only for their roots or leaves, the process doesn't work for plants grown for their flowers, seeds or fruits.