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Difference Between Coleoptile and Coleorhiza

Last updated date: 26th Feb 2024
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Introduction to Coleoptile and Coleorhiza for NEET

Coleoptile and coleorhiza are the layers of the sheath emerging from monocot sheets. They occur in the seed before the germination of the seed. Coleorhiza is the sheath-like structure that connects coleoptile and primary roots. Coleorhiza stays in the soil but coleoptiles emerge from the soil. Before discussing the difference between coleoptile and coleorhiza, let us discuss each term individually.

NEET or National Eligibility cum entrance test is an all-India pre-medical exam to get admission in undergraduate medical courses. Lakhs of students all over the country appear in the exam conducted by National Testing Agency (NTA). The pattern of the question paper is structured in Multiple Choice Questions (MCQ) format.

In order to be able to solve the questions, students are required to have a good conceptual clarity of the topics in the syllabus. To help the students excel in the exam, the faculties make the effort to simplify all the important topics. 

Students can also download the set of question papers for free from the Website or mobile app of Vedantu.

In this article, we will learn the following - 

  • Introduction

  • What is Coleoptile?

  • Physiology of Coleoptile 

  • What is Coleorhiza?

  • Difference Between Coleoptile and Coleorhiza?

  • Conclusion

  • Frequently asked questions


What is Coleoptile? 

Coleoptile is the protective sheath-like structure which covers the pointed shoot in monocotyledons; this is the main function of Coleoptile. Examples for the monocotyledons are grasses in which few leaf primordia and shoot apex of monocot embryos remain enclosed. Coleoptile has two vascular bundles one on each side. 

Coleoptile lacks chlorophyll, so it is generally pale yellow in color and some of them have anthocyanin pigment which imparts purple color. Coleoptile consists of similar cells which are specialized to fast stretch growth. These cells don't divide but they increase their size by accumulating more water. Water vessels in the coleoptile help them to provide water supply.

Once the coleoptile reaches the surface it stops growing. In a later stage, the flag leaves penetrate the top layer of the coleoptile and continue to grow along. Coleoptile consists of the cells which are very similar and specialized to fast stretch growth.


Physiology of Coleoptile 

Coleoptile is a hollow organ having stiff walls which surround the young plantlet. The first coleoptile emerges, appearing yellowish white from the seed before developing into chlorophyll on the next day. Coleoptile grows and produces chlorophyll only for the first day, then it degrades and later due to water potential it grows. Coleoptile length is divided into an irreversible fraction, and a reversible fraction or elastic shrinking. White light increases the water potential in the epidermal cell and decreases the osmotic pressure.

Coleoptile was used to conduct early experiments on phototropism. It showed that plants grow towards light because plants on the darker side elongate more compared to the lighter side. Coleoptiles bend towards light only when their tips are exposed by Charles Darwin and his son Francis. 


What is Coleorhiza?

Coleorhiza is also known as Coleorhiza and root sheath and it is the layer of tissue (sheath-like structure) that surrounds the root in the seed. This is the main function of Coleorhiza which is seen in monocotyledons. Coleorhiza is the first thing that grows out of the seed during germination. Primarily it grows through cell elongation.


What is the Difference Between Coleoptile and Coleorhiza?

Some of the important differences between coleoptile and coleorhiza are discussed below.



Protective sheath covering of coleoptile is conical in grass enclosing plumule.

The protective sheath covering of coleorhiza is undifferentiated in the roots of the germination grass.

Emerges above the soil turning green.

Coleorhiza stays below the soil.

Coleoptile covers the plumule 

Coleorhiza covers the root cap and radicle.

Coleoptile breaks through the seed coat to elongate.

Coleorhiza breaks through the seed coat. however, no further growth is seen. 



After going through coleoptile and coleorhiza functions, definitions individually and then discussing the difference between them. We can conclude that the main difference is between the type of growth and occurrence.

FAQs on Difference Between Coleoptile and Coleorhiza

1. What are the important functions of coleorhiza?

Some of the important functions of coleorhiza are as follows - 

  • It is a protective sheath that envelops the radicle. It is further penetrated by the root in germination. 

  • Thus it protects the root cap and the radical until they come out of the seeds. 

Read the full article to understand the concept well. You can also watch the video lecture on the topic. 

2. What is the best possible way to increase your chance of cracking NEET? 

Every student working with sincerity and dedication has almost similar chances of clearing any exam. But what makes the toppers separate from the others is their level of commitment. Toppers do not stop their preparation by completing the syllabus, rather they take it to another level by solving more questions from the topics of the syllabus. They analyze their mistakes and work on them so that they go well prepared for the real exam. 

So, the simple mantra is to read and understand the topic well, practice more MCQs, Past year papers, and other mock papers provided by Vedantu. Make short notes of the important points and keep revising them for better retention. Study hard, Study-smart and you will crack the exam. 

3. What is the required condition for the germination of a seed?

For a seed to germinate, the following conditions are required -the right amount of water, oxygen, light, and temperature. These are the basic prerequisites for the germination of any seed. However, the amount differs from plant to plant. As some of the seeds require more heat whereas others might require more temperature or water. Thus, an agriculturist, farmer, or botanist needs to be aware of the required conditions of germination of a seed. 

4. What is cotyledon? 

Within the seed of a plant a cotyledon is a significant part of the embryo. This embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed. It supplies the nutrition a plant embryo needs to germinate, this over a period of time they become a  photosynthetic organism and be a source of nutritional reserves themselves. 

5. Is the topic Coleoptile and Coleorhiza important for the NEET Exam? 

The topic is important from the exam point of view. Students will find questions from the topic in the paper, as a good portion of questions is asked from this section of botany. Thus, students should not skip these topics. We have made short notes on such topics which will not consume much of your time and will help you cover the topics well.  To know more about the importance of any topic refer to the past years’ papers and the analysis of the paper done by the experts at Vedantu visit the website. 

6. Why Are Coleoptiles and Coleorhiza Absent in Dicots?

Coleoptile and coleorhiza are necessary for monocotyledons to protect the plumule and radicle of the root respectively. Coleoptile protects shoot apex and leaves enclosing them when they are below the soil and also helps in emerging out of the soil. Coleorhiza protects the root cap and radical till they come out of the seed.

7. How Cotyledons are Formed?

Cotyledons are formed during the process called embryogenesis. During this process, even root and shoot meristems are formed so they are present in seed prior to the germination.

There are two types of cotyledons one is monocotyledons( having one cotyledon) and the other is dicotyledons( having one or more cotyledons).

8. What is the Meaning of Radicle?

The first part of the seed to come out during the process of germination is called the radicle. Radicle is the embryonic root of the plants which grows down the soil.

9. What are the Primary Parts of the Seed?

Seed mainly consists of three main parts: embryo, endosperm and seed coat. The embryo is the young multicellular organisms, Endosperm is the source of stored food and the seed coat consists of one or more protective layers which protect the seed.