How Does a Taproot Support Plant Growth?
A ‘Taproot’ is the main root of a plant, having vertical, thick, and long roots. Every root type has different functional roles and characteristics. In this article, we try to bring all the needed information related to the taproot system.
We often see the plants around us but miss knowing anything about the roots. After reading this article you will get a fair idea about the root system and specifically about the taproot system.
Table of Contents -
Taproot - An introduction
What is a Taproot System?
Development of Taproot System
Different shapes of Taproot System
Advantages of Taproots
Limitations of Taproots
Frequently Asked Questions
What is the Taproot System?
Define taproot - Taproot is the main root of the primary root system, which grows vertically downwards. Most of the dicotyledonous plants like dandelions, produce taproots and some of the roots are edible like carrots and beets, specialized for the storage of the food. Taproot is nearly straight, thicker and taper in size, in the taproot system roots grow directly downwards.
The Taproot system is completely different compared to the adventitious root system or fibrous root system, but some plants which grow as taproot plants during germination will develop branching root structures. Some of them depend on the main root for the storage and may retain the dominant taproot for centuries.
Development of the Taproot System
Once the seed is germinated, the first thing to come out of the seed is the root of the embryonic radicle. This primary root is known as the taproot system; the plant with a tap root system has smaller lateral roots known as the secondary root commonly arises from the main taproot. Secondary roots in turn also produce even smaller lateral roots known as tertiary roots. These lateral roots help to increase the surface area for water and mineral absorption.
Soil characteristics also influence the architecture of the taproot, for example, the deep and rich soils favour the development of vertical taproots in many oak species such as Quercus Kelloggii. And the clay soil promotes the growth of multiple taproots.
Different Shapes of the Taproot System
The typical shapes of the taproot system include the conical root, fusiform root, and napiform root.
Conical Root -
This type of root is conical in shape and it is widest at the top and tapering steadily towards the bottom for example carrot.
Fusiform Root -
This type of root is widest in the middle and it is taper towards the top and the bottom. An example of the fusiform root is radish.
Napiform Root -
This type of root has a top-like structure. The napiform root is broad at the top and tapers suddenly like a tail at the bottom. An example of this type of root is a turnip.
Which Plant has a Taproot System?
Taproots are commonly found in plants like beetroot, burdock, carrot, sugar beet, dandelion, parsley, parsnip, poppy mallow, radish, sagebrush, turnip, common milkweed, cannabis, and trees such as oaks, elms, pines, and firs are some of the taproot plant names.
Advantage of the Plants with Taproot System
The Taproot System has the following Benefits -
The plants with the taproot system are very drought tolerant.
Plants that grow in the desert can send roots down more than 75 feet in the search for water in dry climates.
It also serves to store the food reserves, which makes them more self-sufficient and resilient.
Better penetration to extract minerals from the soil
It serves as a storehouse of nutrients and minerals
The trees and plants with taproots have a stronger hold of the soil and are less susceptible to extractions
Drawbacks of the Taproot System
Apart from the benefits, the taproot system has certain limitations -
It is so deep in the soil that it can be very hard to dig and lift a taproot plant. For a suitable example, you can take dandelions in the yard.
Trees or plants die in the process of translocation of the plants with taproots
Taproot once cut cannot regrow whereas other roots grow easily.
FAQs on Taproot Explained: Structure, Function & Benefits
1. What is a taproot system?
A taproot system is a type of root structure where a single, large, central, and dominant root, called the primary root, grows straight down into the soil. From this primary root, smaller, lateral roots, known as secondary and tertiary roots, emerge. This entire system originates directly from the radicle of the embryo in a germinating seed.
2. What are the primary functions of a taproot?
The primary functions of a taproot are to anchor the plant firmly in the soil, absorb water and essential minerals from deeper soil layers, and conduct them up to the stem. In many plants, such as carrots and beetroots, the taproot is also modified to store food reserves, providing energy for the plant during dormant seasons.
3. Can you give some examples of plants with taproots?
Yes, many common plants feature a taproot system. Notable examples include:
Vegetables: Carrot, Radish, Beetroot, and Turnip.
Trees: Mango, Neem, Pine, and Oak.
Flowering Plants: Mustard, Dandelion, and Hibiscus.
4. What is the main difference between a taproot and a fibrous root system?
The main difference lies in their structure and origin. A taproot system features a single, prominent primary root that grows deep, with smaller lateral branches. It develops from the embryonic root, or radicle. In contrast, a fibrous root system consists of a dense, shallow cluster of many thin, branching roots that originate from the base of the stem, with no single dominant root.
5. How does a taproot develop in a plant?
A taproot develops from the radicle, which is the embryonic root present within a seed. Upon germination, the radicle elongates and grows directly downwards into the soil, forming the primary root. This primary root continues to grow and gives rise to lateral branches, known as secondary and tertiary roots, thereby establishing the complete taproot system characteristic of dicotyledonous plants.
6. Do all edible roots, like onions and carrots, have a taproot system?
No, this is a common misconception. While a carrot is a true taproot modified for food storage, an onion is actually a modified underground stem called a bulb, and its roots are fibrous. Similarly, a potato is a modified stem (tuber). This shows that the edible, underground part of a plant is not always its taproot.
7. Why is a deep taproot system advantageous for plants in certain environments?
A deep taproot system provides significant survival advantages, especially in environments prone to drought. Its ability to penetrate deep into the soil allows the plant to access water and nutrients located far below the surface, which are unavailable to shallow-rooted plants. This ensures better hydration during dry spells and provides strong anchorage against heavy winds, enhancing the plant's stability and resilience.
8. How can a taproot be modified for functions other than absorption?
Taproots can undergo modifications to perform specialised functions. The most common modification is for food storage, where the primary root becomes swollen and fleshy. Based on their shape, these are classified as:
Conical Root: Broad at the base and tapering towards the apex (e.g., Carrot).
Fusiform Root: Swollen in the middle and tapering at both ends (e.g., Radish).
Napiform Root: Spherical at the top and tapering sharply below (e.g., Turnip).
In some plants like mangroves, taproots are modified into pneumatophores (respiratory roots) that grow upwards to facilitate gas exchange.
9. Why do dicotyledonous plants typically have taproots while monocotyledonous plants do not?
This fundamental difference is linked to their embryonic development. In dicotyledonous plants (dicots), the radicle (embryonic root) persists after germination and grows into the long-lived primary taproot. In monocotyledonous plants (monocots), the primary root that emerges from the radicle is short-lived and is soon replaced by numerous adventitious roots that arise from the base of the stem, forming a fibrous root system.
10. Where does the taproot fit within the main types of root systems in plants?
In botany, plant root systems are broadly categorised into two main types based on their origin. The taproot system, which develops directly from the radicle and is characteristic of most dicots, is one type. The other is the adventitious root system, where roots arise from any plant part other than the radicle. The fibrous root system found in monocots is a type of adventitious root system.
