Plant growth begins and ends with a seed or spore. They range in size from tiny fern spores that are barely visible to the naked eye to the giant 44-pound fan palm (Lodoicea maldivica) seed. The inside of the seed contains the genetic makeup of the plant and the cotyledons.
Seeds lay dormant until conditions are right for germination. Most require light, warmth and moisture to germinate. Although some seeds require darkness to germinate, they require light for the young shoot to grow into a seedling.
The root is the first to emerge from a seed and extends downward into the soil. It branches creating finer roots until it forms the tiny hair roots necessary to absorb moisture and nutrients from the soil.
The seed splits and a tiny shoot emerges and reaches for light. The cotyledons open and provide nutrients for the growing shoot until it begins to manufacture its own food from sunlight and water.
As the shoot develops into a seedling, its stem grows thicker and leaves appear. Seedlings begin to make their own energy through a process called photosynthesis. The leaves develop chloroplasts that are filled with chlorophyll. Chlorophyll absorbs sunlight and combines it with carbon dioxide and water to make sugar and oxygen. The plant takes in carbon dioxide and releases oxygen into the air through tiny holes on the underside of the leaves called stoma. The sugar converts to other foods for the plant like starches, proteins and fats.
Roots grow larger, partly to support the weight of the plant, and partly to absorb water and nutrients in the soil and carry them to all parts of the plant. Without water and nutrients like nitrogen, potassium and phosphorus, plants cannot grow strong and healthy.
As seedlings grow and the plant matures, it produces blooms. The flowers must be fertilized to produce the fruit that contains the seeds. Flying insects carry pollen from neighboring plants as they feed on nectar. Some plants are fertilized by the wind. Once fertilized, the fruit begins to grow and ripen.
Seeds are contained in the fruit of plants. After the flower blooms and develops a fruit, the fruit gradually matures producing seeds for new plants. Fruits like apples, pears and oranges must decay to release the seeds. Some plants like peas and beans produce fruit in pods that dry and split when mature to release seeds.