Maintaining underground parts of a plant

The first root that emerges from sprouting seed is the taproot or primary root. It tends to grow straight down and may penetrate several inches into the soil. A fibrous root system is one in which the primary root ceases to elongate, leading to the development of numerous lateral roots.

Experienced gardeners know that the health and the yield of the above ground part of their plants depend on the below ground parts, the roots. These roots are needed to supply water and nutrients, provide support and anchor the plants in the soil.

The structure and growth habits of the roots have a pronounced effect on the size and vigor of the plant. They have an effect on the response to irrigation, adaptation to different types of soils and the uptake of nutrients.

Roots typically originate from the lower portion of a plant or cutting. They have a root cap, have no nodes and never bear leaves or flowers directly.

The first root that emerges from sprouting seed is the taproot or primary root. It tends to grow straight down and may penetrate several inches into the soil. It becomes the central leader and an important feature of the root system. Some trees, especially pecan trees, have a long taproot with very few lateral or fibrous roots. This makes them difficult to transplant and necessitates planting only in deep, well-drained soil.

If plants that normally develop a taproot are undercut early in life, the root will lose its taproot characteristics and develop a compact, fibrous root system. This is done at commercial nurseries so that trees will develop a fibrous root system and allow a higher rate of transplanting success.

A fibrous root system is one in which the primary root ceases to elongate, leading to the development of numerous lateral roots. These lateral roots will branch and form the feeding system of the plant.

A fibrous root is one that remains small in diameter because of a lack of significant green growth activity. Shrubs and dwarf trees remain smaller than standard trees because of their fibrous root systems. Grasses and related plants such as corn, onions, daffodils and lilies replace the initial taproot with the fibrous root systems.

As plants become established, the root system develops laterals and extends far beyond the spread of branches. For most cultivated crops, roots meet and overlap between the rows. The greatest concentration of fibrous roots occurs in the top foot of soil, but a significant number of laterals may grow downward from these roots to provide an effective absorption system several feet deep.

The most important function of the roots is collecting water and nutrients from the soil through root hairs. The root hairs will collect water and mineral nutrients that are present in the soil and take this solution up through the roots to the rest of the plant. Root hair cells can survive for 2 to 3 weeks and then die off, At the same time, new root hair cells are continually being formed at the tip of the root.

Water and nutrients absorbed by the roots is pumped up to the stems and leaves through a pipeline system of hollow cells called the xylem. Similarly, dissolved sugars and other substances produced in the leaves and shoots circulate down the roots through a secondary circulatory system called a phloem. The sugars supply the energy that roots need to grow and function.

Roots hold plants upright and in place. The obvious example is a tree that can remain erect despite high winds. Bulbs such as tulips and daffodils and perennials, such as hosta and daylilies, have contractile roots that actually pull the plant down closer to or deeper into the soil.

Some plants, particularly members of the legume family such as beans and alfalfa, host bacteria in their roots. Infected roots have characteristic round swollen areas called nodules that contain the bacteria. Even though the bacteria consume a share of the plant’s sugar, the plant benefits because these bacteria can gather nitrogen from the air and convert it into compounds that roots can absorb.

Jim Coe lives in Lawton and writes a weekly gardening column.