Here's your ultimate guide to roots... tree, plant and flower root systems that is. We set out and explain the different types of roots as well as root functions (what they do) and include an illustration showing the anatomy of a root system.
Roots are the non-leaf part of a plant’s body that does not bear any nodes. It is the organ that lies below the surface of the soil. Roots can also be aerial i.e. growing above the surface of the ground or aerated which means floating over the surface of the water. Roots are responsible for providing the stems and the leaves with adequate water and nutrients for their growth.
Roots form a major part of a plant body, in terms of bulk and function. The major functions of the roots are as following:
Anchor and Support
The root system of the plant provides physical support by anchoring the plant body to the soil. Many plants can stand erect for hundreds of years because their roots grow deep into the soil and hold the plants strongly in place.
Absorption and Conduction
Roots have root hairs through which roots absorb water and nutrients from the soil which are essential for the plant growth. Roots have a capability of absorbing inorganic nutrients against the concentration gradient. After the water and nutrients are absorbed, they are moved upwards to stem and leaves.
In deserts, roots grow deep into the permanent water reserves. Desert areas where plants are found to be growing are considered to have underground water reserves. This greatly helps in deciding where to dig a well.
Roots have specially designed channels for the transport of absorbed nutrients and water to stem and leaves. Moreover, they also have channels through which organic food can be transported from aerial parts of the plant to the roots.
Some roots like carrots and sweet potatoes serve the purpose of a storage organ. They store carbohydrates and water. Roots of some plants found in desserts can store up to 70kg of water.
Photosynthesis is the process by which plants prepare their food. Some roots are capable of photosynthesis as is the case with aerial roots of mangrove plants and epiphytic orchids.
Plants that grow on the surface of stagnant water have specialized roots that are called pneumatophores which diffuses the oxygen from the air.
Contractile roots of many bulb-forming plants pull the plant downwards into the soil. Environment under the soil is more favorable for bulb-forming plants.
Some special roots are capable of reproduction. They serve as a means of perpetuating a species. In some plants like the mature agoho, offshoots are seen growing around the trunk profusely from roots that are growing horizontally.
Anatomy of Roots
The root has four main regions:
- Root Cap
- The meristematic region
- The region of elongation
- The region of maturation
The root cap is present at the apex of a root. It is a thimble-like structure. The apex of a root is tender. A root cap protects this tender end and aids the root in propagating deeper into the soil. The root cap secretes mucilage which is responsible for lubricating the passage for the root through the soil. This mucilage also aids in the absorption of water and nutrients. Root cap wears out but it is renewed constantly.
The Meristematic Region
The term meristematic means rapid growth. This region is present just above the root cap. The cells in this region grow rapidly. They are very small and extremely thin-walled. They have dense protoplasm.
The Region of Elongation
The cells in the region of elongation rapidly enlarge and elongate. The cells in this region are responsible for the growth of root length.
The Region of Maturation
The cells in the region of elongation gradually mature after differentiation and form the region of maturation. The cells differentiate to form various specialized tissues like permanent region and root hairs.
Monocot Roots and Dicot Roots
Roots of a monocotyledon plant are called monocot roots and roots of a dicotyledon plant are called dicot roots.
Monocotyledon plants have a single cotyledon in their embryo. In monocot roots, xylem and phloem are arranged in a circular manner. Dicotyledon plants have two cotyledons in their embryo. In dicot roots, xylem is present in the middle and phloem surrounds it.
Difference Between Monocot Roots and Dicot Roots
The pericycle gives rise to lateral roots only. The pith is well developed and large. Numerous xylem and phloem are present in monocot roots. There is no secondary growth.
The pericycle gives rise to several lateral roots, cork cambium, and some part of the vascular cambium. The pitch is absent. There is a limited number of xylem and phloem. Secondary growth occurs in the dicot root.
Types of Roots
There are different types of roots depending upon the type and species of plants. The major types are:
1. Fibrous Roots
Fibrous roots are found in monocot plants. They are slender, branched, and grow directly from the stem. These roots tend to grow close to the surface and spread horizontally. They are characterized by a cluster-like appearance with numerous roots together, all nearly of the same size. In the fibrous root system, the primary root is short-lived. It is replaced by numerous roots.
Fibrous root system does not provide strong anchorage to the plant as they do not penetrate deep into the soil.
- Fibrous roots grow from the base of the stem
- They are underground
- They are present in the form of clusters of similar-sized roots
- The primary root is replaced by adventitious roots
- They do not penetrate deep into the soil.
Taproots are found in the majority of dicot plants. This type of root is a direct elongation of the radical. Unlike fibrous roots, taproots are not branches. Instead, they are a single primary root that grows deep into the soil. A taproot gives rise to lateral branches (secondary and tertiary roots) leading to the formation of a taproot system.
The branches of a taproot grow in acropetal succession which means, the longer and older ones are present at the base while newer, shorter ones are near the apex of the primary root.
Taproot system provides a very strong anchorage. The reason for this strong support is that they penetrate deep into the soil.
In some plants, the taproot does not grow too deep. Instead, its lateral branches grow longer horizontally along the surface. These types of roots are called feeder roots.
- Taproots develop from radical of an embryo
- They are always under the surface of the soil
- They have one main root (primary root) with branches that grow in an acropetal manner
- The primary root remains throughout the life f the plant
- They act as deep feeder, that is, they penetrate deep into the soil.
3. Adventitious Roots
Adventitious roots are similar to the fibrous roots. However, they can be underground or aerial (above the ground). They can grow from any part of the plant except the radical. Usually, they grow from intermodal, stem nodes, and leaves. These roots can be thick, thin, or modified according to the species. Adventitious roots arise under stress conditions such as waterlogging after floods.
Leaf cuttings and branch cuttings in plants such as rose can result in the development of adventitious roots. They also develop in cases of plant injury. They can increase the survival chances of a plant as the plant propagates itself with the assistance of adventitious roots.
4. Creeping Roots
5. Tuberous Roots
Tuberous roots are very thick roots. They store significant amounts of food to feed the whole plant. They are a fleshy, enlarged, and modified storage organ. They are modified from the stem.
The propagation of tuberous roots is by crown division where each crown division has several buds and sufficient storage to make a new plant.
6. Water Roots
Water roots are the types of roots that plants in water grow. They are finer and more brittle. They have a capability to allow oxygen from the atmosphere to diffuse in which is then used by the roots for metabolism and growth. They are morphologically different from soil roots.
7. Parasite Roots
Parasite roots are types of roots that attach themselves to the other plant and suck nutrients from it. They do not offer any benefit to the host plant. Instead, they cause serious damage, hence the name, parasite roots.
The facts about roots listed below are some amazing pointers that we are sure you have never heard of before:
- In most of the plants, the growth underneath the ground (as roots) is as much as the growth over the ground.
- The crops that are grown on dry land have 90% of their roots in the top 10cm of the soil. The remaining 10% of the roots grow as deep as 2m to reach deep water for survival.
- When the conditions are ideal, roots can grow as fast as 1cm a day.
- The soil whose strength is less than 3 Megapascals is suitable for the growth of roots.
- The growth of roots is random but they grow faster and branch more in areas where soil conditions are favorable.
- The growth of roots is not towards the water or fertilizer. Instead, they grow around these areas as it promotes growth.
- The majority of water and fertilizer absorption in roots occur a few millimeters above the growing tip.
- Roots that are old serve as a pipe for the transfer of water and nutrients to other parts of the plant.
- In areas where a disease attacks the root tip or where growth is restricted, water and nutrient uptake will be restricted.
Uses of Roots to Man
Roots are widely used by man. Some of the most prominent uses of roots to man are:
- Many roots are used as food by humans. These roots include carrots, yam, potato, and radish.
- Roots are a source of some important medicines that have life-saving potential. Plant medicines such as ginseng, ipecac, Rauwolfia, ashwagandha are obtained from the roots.
- Roots contain a lot of fiber. The fiber from roots is used to make brooms, baskets, brushes, etc.
- Roots help in the prevention of soil erosion by soil conservation.
- By preventing soil erosion, they play a major role in the prevention of desertification.
Important Medicines Made From Roots
As mentioned earlier, roots are a source of some very important medicines. We have listed down the most prominent ones for you.
Turmeric root is capable of treating anything from stomach pain to arthritis, to disorders of gallbladder and liver, to menstrual cramps, to infection and headaches. Turmeric is mostly used as a spice but the medicinal uses of turmeric root are just phenomenal.
Ginger is effective in cases of diarrhea, nausea and upset stomach. It can also be used for relief from cold, congestion, flu, and headaches.
Licorice has been used for ages to treat stomach ulcers, bronchitis, and sore throats. According to some studies, licorice can also be helpful in the treatment of hepatitis C.
This medicinal root can be used to treat arthritis, liver diseases, and fibromyalgia.
Valerian is used for treating sleep disorders. Many people who are struggling to get out of their habit to consume sleeping pills have benefitted from Valerian. Some studies suggest that this herb can make chronic insomniacs fall asleep more easily and quickly.
Who knew roots were such magical part of a plant? Not just they are the heart and lungs of a plant but they offer enormous benefit to humans.