Flowers are one of the ways many plants reproduce. Other ways include bulbs, rhizomes, runners and cuttings. Flowers grow as an annual. which means it goes through the entire life cycle, including death, in one growing season, or a perennial. Perennials go dormant at the end of the season but the plant rejuvenates and grows back the following season. It doesn't die. Trees flower as well. No matter what the type of plant, the life cycle is relatively the same.
The husks or shells of the seeds are hydrated with water and soften allowing the embryonic root to break out followed by the stem and two leaves. Some seeds such as Shasta daisies require light to germinate but most don't. They do require water and warmth. Soil isn't a prerequisite. Seeds will germinate in a damp paper towel. However, it's difficult to transplant a seed that has germinated without soil into the soil.
After the flower has germinated, it has a stem and two leaves at the top of the stem on either side. The true leaves of the flowering plant appear after a week to two weeks and resemble the leaves of the plant, whether round and small, long and thin, notched or feathery.
The seedling grows until it reaches the size necessary to begin setting flower buds. In the case of a Thumbelina zinnia this may be as short as 6 inches or in the case of cosmos it can be 3 to 4 feet. Trees may take several years to reach an adult size tall enough for flowering.
The plant begins to flower by setting buds. In the case of annuals they flower all season until the seeds are produced. Deadheading annuals or removing the spent blossoms keeps the plant blooming because it has to set seed. Perennials and trees bloom for a shorter time, in some cases just a few weeks. Fruit trees may bloom for only a week to 10 days.
The flower's purpose is to produce the reproductive material for the next generation through seeds. The seeds can be in pods like oriental poppies or at the end of the petals like zinnias. Seeds are also encased in fruits. Fruits are the ovaries of the plants and are often edible, if not by humans then by birds and animals.
Annuals die at the end of the growing season. While their life can be extended by bringing them inside before frost they will die anyway because it's in their genetic code. Eventually perennials will die as well as trees. How long they live depends on the species and their care. Some trees will live for hundreds of years. The world's oldest living tree is a spruce in Iceland with a calculated age of 9,550 years, according to Science Daily.