Difference Between Root Hair and Stem Hair

The key difference between root hair and stem hair is that the root hair is a unicellular structure developed as an outgrowth of the epidermis, while the stem hair is a multicellular structure that is not an outgrowth of the epidermis.

Root and stem are two main parts of a plant. Stem exists above the surface of the soil while root exists inside the soil. Stems grow upright while roots grow towards the soil. Hence, stem shows positive phototropic movements, while root shows positive geotropic movements. Stems have stem hairs, which are multicellular structures. Similarly, roots have root hairs, which are unicellular structures. Structurally, stem hairs are additional cells, while root hairs are outgrowths of the epidermis. Likewise, there are many other differences between root hair and stem hair, which we will be discussing in this article.

CONTENTS

1. Overview and Key Difference
2. What is Root Hair 
3. What is Stem Hair
4. Similarities Between Root Hair and Stem Hair
5. Side by Side Comparison – Root Hair vs Stem Hair in Tabular Form
6. Summary

What is Root Hair?

Root hair is an important structure of a plant. It is a unicellular and tubular structure developed as an outgrowth of epiblema cells. Moreover, these hairs are present only at the zone of maturation of the root tip. Generally, these hairs are unbranched lateral extensions designed to absorb water and nutrients from the soil. Hence, root hairs have a large surface area. Water enters the cytoplasm of root hair cell via osmosis. It occurs due to the low water potential of the root hair cell compared to the water potential of the soil solution.

Root hairs are visible under the light microscope as well to our naked eye. Unlike other plant cells, their cells do not contain chloroplasts. Also, these hairs survive a short time, and new hairs replace the old ones constantly. Their lifetime is about two to three weeks, and then they die, allowing new root hairs to emerge.

What is Stem Hair?

Stem hairs are multicellular structures distributed throughout the stem of a plant. Unlike root hairs, they are not outgrowths of the epidermis. They are additional cells. And, the major function of the stem hairs is the reduction of the rate of transpiration.

Moreover, stem hairs are cutinized, unlike root hairs. Also, they can be branched or unbranched. Besides, they survive for a long time on the stem of the plants.

What are the Similarities Between Root Hair and Stem Hair?

• Root hair and stem hair are two structures of plants.
• They are lateral extensions.
• Also, both structures are important since they carry out significant functions in the plants.
• Moreover, both are visible to our naked eye.
• Some stem hairs and all root hairs are unbranched.

What is the Difference Between Root Hair and Stem Hair?

Root hair is an outgrowth of the epidermis, which absorbs water and nutrients from the soil. Whereas, stem hair is a lateral extension present on the stem, which reduces the transpiration. It is not an outgrowth of the epidermis. So, this is the key difference between root hair and stem hair. Furthermore, root hair is always a unicellular structure, while stem hair is mainly multicellular. Therefore, this is also a significant difference between root hair and stem hair.

Moreover, root hair is always unbranched, while stem hair can be unbranched or branched. Also, stem hairs are present everywhere in the stem, while root hairs are present at a particular region of the root.

The below infographic summarizes the difference between root hair and stem hair, comparatively.

Summary – Root Hair vs Stem Hair

Root hairs are outgrowths of the epidermis of the roots while stem hairs are lateral extensions present throughout the stem of the plants. But, they are not outgrowths of the epidermis. So, we can consider this as the key difference between root hair and stem hair. Furthermore, root hair is unicellular while stem hair is mainly multicellular. Apart from that, root hair is unbranched while stem hair can be branched or unbranched. Moreover, root hair absorbs water and nutrients from the soil while stem hair reduces the rate of transpiration. Thus, this summarizes the difference between root hair and stem hair.

Reference:

1. Grierson, Claire, and John Schiefelbein. “Root Hairs.” The Arabidopsis Book, American Society of Plant Biologists, Available here.

Image Courtesy:

1. “NSRW Root-Tip” (Public Domain) via Commons Wikimedia
2. “Cap1033-botao1” By The original uploader was Lrothc at English Wikipedia. – Transferred from en.wikipedia to Commons (CC BY-SA 2.5) via Commons Wikimedia