The roots play a fundamental role in the functioning and therefore in the production of plants. It is thanks to them that the supply of water and mineral elements of this one is made. But there are other functions: anchorage on the substrate, reserves in assimilates, metabolism.
The roots contribute in particular to the hormonal balances which control the growth and the functioning of the plant. They also constitute a source of organic matter for the soil; it is even sometimes the only regular restitution in many cropping systems in tropical zones.
It is therefore important for crop production, but also for maintaining soil fertility, to have a well-developed root system, especially at depth.
What is the purpose of roots on plants?
The root system allows the plant to absorb the water and nutrients (mineral salts in the form of ions) it needs to live. To do this, the roots are equipped with absorbent hairs at their ends, which increase the already large surface area of root/soil contact: the greater the surface area, the easier the exchanges.
The roots also allow the plant, incidentally, to anchor itself in the soil: without roots, plants would be carried away by the wind or runoff water. This is particularly true for trees: the large woody roots stabilize the tree, the absorption function being ensured by the rootlets (called “root hair”).
Finally, roots serve as reserve organs: this function is obvious to plants with tuberized or rhizomatous roots (especially those that produce tubers), but also for others, notably perennials whose foliage disappears in winter: before the leaves fall and/or the aerial parts degenerate, the sap descends into the roots, in order to store a reserve of nutrients that will allow a rapid restart the following spring.
What are three things roots do for plants?
The 3 main functions of a root for each plant on earth are quite logical:
- The root allows the plant to “hang on” in the soil, and therefore not to be blown away by the wind or anything else
- More importantly, the roots allow the plants to absorb water and minerals from the soil, without that, it is impossible for a plant to survive.
- In the same way as for water and minerals, the root of the plants stores and makes a reserve of “food” when it can, it is just as important to the survival of the plant.
Without these 3 key points, it is impossible for a plant to survive, the root can be compared to the brain of a human being in plants.
What are the 4 different types of roots in plants?
There are different types of root systems, with all types in between, and even plants with roots of several types. The architecture of the root system depends on the species to which the plant belongs, but not only: it also depends on the availability of nutrients, the type of soil, its composition…
1. Adventitious roots
Adventitious roots are formed on the stems, starting from a node. Adventitious roots are often complementary to another type of root system. For example, in some lilies, adventitious roots appear in the buried part of the stems, above the bulb, which is the origin of fasciculated roots.
Adventitious roots can also be observed in tomatoes, corn… and all plants that multiply by stem cuttings or those that have creeping stems capable of rooting (mint, periwinkle…) or that emit stolons (strawberry plants)!
2. Taproot system
This type of root system is found in particular in Dicotyledons and Gymnosperms. It is characterized by a main root which sinks vertically into the soil, and on which secondary lateral roots develop.
Allowing a particularly effective anchoring, the taproot is feared by the gardener wishing to pull out weeds (the dandelion is a good illustration)… or to transplant a plant badly placed. The oak and the tomato have a taproot. Note that a taproot can be tuberized: radish, carrot, beet…
3. Tracing roots
Tracing roots develop horizontally below the soil surface. On this type of root, complementary stems and roots can appear, giving rise to a new plant. Trailing roots are typical of many bamboos and ground covers that can form large mats.
4. Fascicular root system
Observed in many Monocotyledons, the fascicular root system forms, as its name indicates, a bundle: the roots all start at the same point, and there is no predominance of a main root.
This is typically the case with bulbous plants: the roots appear from a plateau. Grasses and corn are other examples. Fasciculated roots can also be rhizomatous (dahlia).
How do the roots develop?
The growth of the root system of most species goes through common stages: the development of a vertical pivot and then its branching into horizontal roots that will exploit the soil in a radius of several meters for trees. This system then emits, near the base of the stem, vertical and oblique roots that will functionally replace the initial pivot.