Among the numerous differences which dicotyledons and monocotyledons have, none is as dissimilar as their root structure. Dicots have tap roots while monocots have fibrous roots. The latter type is also often referred to as adventitious roots.
The differences between tap roots and fibrous roots are many. Not only do they share differing structures they also have varying roles to play in the plants’ lifetime.
As advanced students of biology, you must be abreast of these differences and similarities. To understand and absorb these complex topics you must first learn a bit more on these roots themselves.
What is a Tap Root?
A tap root is a single root which burrows deep into the ground. It has very few lateral roots or outgrowth; it is also often quite straight, provided the surface is suitable. It is simply a differentiation of a dicot’s primary root, formed when the seedling is still in its developmental phase.
Tap roots are unique and identifying features of all dicotyledons.
These roots can act as food storage units for plants. They also provide excellent anchoring. Flowering dicotyledonous plants- like dandelions, roses, sunflowers and marigolds- are rather difficult to pull out thanks to their root structure.
Now, take a look at a rose’s tap root system below.
Although the image above is not in colour, you can observe the single thick root with minimal outgrowth.
A tap root system can penetrate a long way underground. They are thus effective in searching for valuable nutrients. This singular property also helps dicots withstand long periods of drought or low rainfall.
Did you know?
A mesquite plant (Prosopis velutina or velvet mesquite is a good example) can have tap roots extending more than 150 feet below ground! Research on the Internet on how these plants play an important part in desert ecology!
Here is an image for you below of a velvet mesquite tree in Texas, USA.
What is a Fibrous Root?
A fibrous or adventitious root system is seen in monocots. The root does not have any single and central structure. Instead, this root system looks like a mesh of evenly-sized, thick, hair-like structures. Such roots do not penetrate too deep underground.
Such a root structure can grow underground- into the soil- and even aboveground. In this latter instance, it is called an ‘aerial fibrous root.’ At times, fibrous roots can grow in all directions around a plant.
One rule-of-thumb difference between a tap root and fibrous root is that the former can never form over-ground.
Notably, these roots prevent soil erosion. Since they are extensively large, they are capable of accumulating resources and nutrients even in arid land. However, note that these roots are not as survival-capable as the monocots’ tap roots.
Many flowering plants have fibrous roots. These include lilies, tulips and daffodils.
Trivia: Lilies come in many shades. The orange lily is commonly held to be the most rarely bred because they consume a lot of water.
Now, here is how lily roots look like.
Apart from appearances, there are several aspects in which these two root types differ. For your benefit, they have been presented in a tabulated manner below, alongside a picture.
Tap Root and Fibrous Root Similarities
These two root types have some similar features. The crucial ones are:
Both have the ultimate goal of absorbing water and essential nutrients from the soil.
Both may grow underground, unlike some other root variants which almost exclusively grow aboveground.
Both variants provide anchorage to its mother plant.
Lastly, these variants are only found in higher plants i.e. vascular plants.
Tap Root and Fibrous Root Examples
Given below for your quick reference is a list of examples.
Plants with tap roots include beetroot, parsley, parsnip, carrots, dandelions, radish and cannabis.
Plants with fibrous roots include wheat and rice, clover, onions, bamboo and millet.
Tips to Easily Handle NEET
Besides reading up and memorising on the list of plants with tap roots and those with fibrous roots, there are some other ways on how you can handle botany-based questions in general and the NEET exam overall.
Start remembering the diagrams of botany-based questions which have appeared in previous years’ papers. These will help you learn and retain the basic concepts without too much text to digest.
You must have noticed how it is easier to remember those essential differences between tap roots and fibrous roots once you have seen photos of actual examples.
Along with reading the best NEET books, make sure to have adequate rest. Also, stick to a good diet and sleep routine for better performance.
1. Which live longer- plants with tap roots or those with fibrous roots?
Ans. It has been observed that plants with tap roots live longer on average than those with adventitious or fibrous roots.
2. Which root type will provide greater support to a plant in case of strong winds or storms?
Ans. Plants with tap roots are much more difficult to uproot than those with fibrous roots. That is why roses, as pictured above, are difficult to root out with a single pull. But onions, which have fibrous roots, are easier to pull out.
3. Which of these two root systems store food or nutrients for a tree?
Ans. Tap roots are the ones which store food and nutrients for a tree. Fibrous roots do not have any such function.