Roots vs. Shoots of Plants

Roots

• Plant roots develop into one of two basic forms. A taproot is a long, narrow, stemlike structure that grows straight downward into soil. A fibrous root system, however, develops many small roots that grow in all directions beneath the soil surface. Taproots can extend great distances vertically to reach water and nutrients; often they grow to a depth of 3 or more feet, depending on the amount of rainfall and available groundwater. Fibrous roots generally do not run so deep but can grow horizontally great distances from the rest of their plant, as in the case of trees with roots extending 25 or more feet just below the soil surface. A taproot can evolve into a compound root by growing smaller side roots along its length, which helps the plant take in more moisture and nutrients. Adventitious roots often appear along the main stem of plants that climb, and each adventitious root can produce a new plant.

Shoots

• Shoots develop from roots but above the soil surface. Each shoot is composed of a main stem, leaves and, eventually, flowers and fruit or seeds. A shoot also can be a new plant that develops at the base of an established plant or along its main stem. A shoot can live separately from the main plant when the shoot develops its own root system. An example of a lateral shoot is a sucker that develops at the base of a corn plant (Zea mays) or at the junction of the main stem and a leaf node on a tomato plant (Solanum sp.) A close inspection of that kind of shoot reveals tiny nodules that would develop into roots if the shoot were placed in water or a rooting medium.

Function

• Although roots and shoots can live independently of each other in certain circumstances, they usually cannot do so for very long without an effect on their survival. A root with a shoot that died sometimes can be revived, as can a shoot that was severed from its base, or root; both plant parts are genetically programmed to keep trying to grow as long as they can. In some kinds of plants, such as grass (Poaceae sp.), the development of the shoot, or foliar part, is related directly to root development. That is why lawn-care professionals recommend removing no more than one-third from grass when mowing; roots are affected significantly if too much of a plant is removed. Removing more than one-half of a grass plant may cause serious damage from which the plant can't recover.

Process

• In order for all parts of plants to develop properly, the roots and shoots must function to the best of their ability. The roots must have access to sufficient moisture and nutrients. Roots growing in dense, rocky soil have difficulty, which can affect the shoot's growth. Also, the shoot must be able to absorb sunlight for the purpose of food production, or the whole plant, including the roots, may die.