How a Plant Grows With Seeds

Seeds

Every plant seed that has been fertilized houses a microscopic plant embryo in it. The embryo is surrounded by tissue that is packed full of nutrients, including proteins and carbohydrates. The embryo and surrounding tissue is protected by a hard seed shell, or coat, that protects the plant embryo from water and other things that could damage it. The seed coat has light-sensitive chemicals in it that can sense if there is enough sunlight to allow germination. If there is, the seed coat will change, allowing water to enter and start the process of sprouting.

Germination

Once water enters the seed, it begins to swell. It takes in water until it bursts, at which point a radicle, which is the precursor to the root of the plant, emerges from the bottom of the seed to seek out more water and nutrients. The embryo consumes the nutritive tissue, developing until it sends out a shoot. This is called germination. The shoot grows until it emerges above the surface of the soil and develops the first leaves, called seed leaves. This young plant is then called a seedling.

Fertilization

If the seedling is a seed-producing plant, it will develop ovules that are housed in the flower. The ovules will eventually become seeds if they are fertilized. The ovules are surrounded by the ovum, which is found in the flower's pistil. The pistil is located at the center of the flower and contains a long hollow tube that leads to the ovules. Surrounding the pistil are stamen, which are composed of anthers. The anthers house pollen sacs. When the pollen grains are mature, the anthers burst open, releasing pollen onto the stamen. When insects or the wind transfer the pollen onto the pistil, the pollen grains thread a pollen tube down the pistil and send male sperm down along it to fertilize the seeds.

Dispersion

The seeds and surrounding tissue (which becomes the fruit) eventually ripen and leave the plant. This is called dispersion. If animals consume the fruit, the seeds will be dispersed when the animals void them. Sometimes, the fruit drops to the ground and rots, leaving the seeds exposed, where they can be picked up in the fur or feet of animals and moved.