What Are Plant Fibres Definition Types Structure and Uses
Plant fibres are derived from plants. Plant fibres, also called fibre crops, are elongated thick-walled cells with pointed ends which consist of cellulose and may or may not contain lignin. Fibre Crops are grown for their fibres, which are used for making paper, rope, and cloth. In medical practice, they are used as a surgical dressing made up of natural or artificial materials. Fibres may be modified chemically like in viscose. There are different types of plant fibres like jute, flax, cotton, etc. Commercially, fibres are used in the textile industry for weaving the cloth, as a filtering medium, and also for insulation purposes.
Types of Fibre
Fibres obtained from various sources can be categorised as follows:
Plants fibres (Example: Jute, flax, cotton, hemp)
Animals fibres (Example: Silk, wool)
Regenerated and Synthetic fibres
i) Fibres generated from carbohydrate materials (Example: rayon).
ii) Fibres generated from protein materials (Example: Aridil from milk casein).
Mineral fibres (Example: Glass, asbestos)
Examples of Fibre Crops
Cotton
Biological Source
Cotton consists of the epidermal trichomes or hairs of the seeds of cultivated species of the Gossypium (Gossypium herbaceum, Gossypium barbadense ), belonging to the family Malvaceae.
Preparation of Absorbent Cotton
After flowering, the plant bears fruits which are known as capsules. The fruits are 3 to 5 cells. Each capsule contains numerous seeds. The hairs from which seeds are covered are known as bolls. Then these balls are collected and dried and taken to the ginning press. Various devices separate the hairs. Linters are the hairs with a short length which are used for the manufacture of absorbent cotton. While long hairs are utilised for the cloth preparation. After mixing with a soda ash solution, it is put under pressure for about 10-15 hours. It is then treated with a suitable bleaching agent after washing it with water. Then it is dried and carded into flat sheets. Finally, it is packed in wrappers. Afterward, it is sterilised by means of Gamma radiation.
Description
Colour - White (due to bleaching)
Odour - Odourless
Taste - Tasteless
Size Cotton fibres are 2.5 - 4.5 cm, in length, and 25 - 35 diameters.
Chemical Constituents
Raw cotton contains about 90% of cellulose, 7 to 8% of moisture, wax, fat, and remains of protoplasm. Purified cotton or absorbent cotton comes with 6 - 7 % of moisture and is entirely cellulose.
Chemical Tests
First, Cotton fibres are soaked in iodine water and then dried. Then the addition of few ml. of 80% sulfuric acid trichomes which assume the purplish-blue or bluish-green colour
Ammoniacal copper oxide solution dissolves raw cotton fibres with the formation of balloons. While absorbent cotton dissolves completely with uniform swelling.
Cotton is insoluble in dilute sodium hydroxide solution and hydrochloric acid. It is soluble in 66 % of sulfuric acid.
Uses
Cotton is used as a filtering medium in surgical dressings and also as an insulating material. Cotton absorbs blood, mucus, pus and it prevents wounds from infections.
Storage
Absorbent cotton should be stored in a cool place. Cotton is made friable and brittle by the bacterial contamination. The absorbent cotton should be wrapped in wrappers to avoid dust and microbial contamination. Heat and long storage make absorbent cotton non-absorbent.
Jute
Biological Source
It consists of phloem fibres of the stem of various species of the Corchorus (Corchorus olitorius and Corchorus capsularis Linn.) and Family Tiliaceae.
Chemical Constituents
The fibres are yellowish-brown in colour and contain cellulose (53%), hemicellulose (20%), and lignin (10 %).
Chemical Test
The middle lamella is highly lignified and gives a red colour with phloroglucinol and hydrochloric acid.
Uses
It is used in the manufacture of tows, padding splints, filtering, and straining mediums. Jute fibres are used for the preparation of coarse bags (Gunny bags).
Flax
Biological Source
These are pericyclic fibres obtained from the stem of the plant Linum usitatissimum belonging to family Linaceae.
Uses
The fibres were earlier used in the manufacture of lint, but at present cotton has replaced these fibres. It is used in the preparation of rugs, lace, lawn, and filtering medium.
Difference between Natural and Synthetic Fibre
Fibres are used as a raw material to make garments, clothes or any other applicational types of equipment. There are two types of fibres based upon the source of production. Natural fibres that are obtained from plants, animals or minerals and synthetic fibres that are obtained through chemical processes with the help of machines. Some of the examples of natural fibre include cotton, jute, silk, etc. And synthetic fibre includes polyester, Nylon, rayon, etc. However, there are a lot of differences between natural and synthetic fibres which are as follows:
Difference between Natural and Synthetic Fibre
Sample Questions
What are natural fibres?
What are plant fibres? give example
Differentiate between natural fibre and man-made fibre
What are the advantages of using natural fibre over man-made fibre?
Explain the type of fibre and give examples of each.
How is cotton prepared and what are its uses?
This was all about plant fibres. To learn more, access all the free resources available on the Vedantu website for the state board, CBSE, ICSE and competitive examinations.
FAQs on Plant Fibres in Biology Structure Types and Importance
1. What are plant fibres?
Plant fibres are elongated, thick-walled sclerenchyma cells that provide mechanical support and strength to plants. These fibres are composed mainly of cellulose and are found in various plant parts.
- They have narrow lumens and thick secondary cell walls.
- They are usually dead at maturity.
- They are important for both plant support and commercial uses like textiles and ropes.
2. Where are plant fibres found in plants?
Plant fibres are found in the vascular bundles, cortex, pericycle, and sometimes in the fruit wall of plants. Their location depends on the type of fibre.
- Bast fibres – found in the phloem (e.g., jute, flax).
- Leaf fibres – found in leaves (e.g., sisal).
- Surface fibres – found on seeds or fruits (e.g., cotton).
3. What is the function of plant fibres?
The main function of plant fibres is to provide mechanical strength and support to the plant body. They help plants withstand bending, stretching, and external stress.
- Strengthen stems and leaves.
- Protect vascular tissues.
- Help maintain plant shape and upright growth.
4. What are the types of plant fibres?
Plant fibres are classified into different types based on their origin in the plant body. The major types include:
- Bast fibres – obtained from phloem (e.g., jute, hemp).
- Leaf fibres – obtained from leaves (e.g., sisal).
- Seed fibres – obtained from seeds (e.g., cotton).
- Fruit fibres – obtained from fruits (e.g., coir).
5. What is the difference between fibres and sclereids?
The main difference between fibres and sclereids is that fibres are long and slender cells, while sclereids are short and irregularly shaped. Both are types of sclerenchyma tissue.
- Fibres: elongated, tapering ends, mainly for support.
- Sclereids: isodiametric or irregular, found in seed coats and nutshells.
- Fibres form bundles; sclereids are usually scattered.
6. How are plant fibres formed?
Plant fibres are formed by the differentiation of meristematic cells into sclerenchyma cells with thick, lignified secondary walls. The process involves:
- Cell elongation.
- Deposition of secondary cell wall rich in cellulose and often lignin.
- Loss of protoplasm, making the cell dead at maturity.
7. What is bast fibre in plants?
Bast fibre is a type of plant fibre obtained from the phloem tissue of dicot stems. It is widely used in making ropes, textiles, and sacks.
- Examples: jute, flax, hemp.
- Located in the inner bark region.
- Known for flexibility and tensile strength.
8. Why is cotton considered a plant fibre?
Cotton is considered a plant fibre because it consists of elongated epidermal cells from the seed coat of the cotton plant. These fibres are rich in cellulose and are classified as seed fibres.
- Develop from the outer surface of seeds.
- Highly used in textile manufacturing.
- Soft, flexible, and absorbent.
9. Are plant fibres living or dead cells?
Plant fibres are usually dead cells at maturity because they lose their protoplasm after developing thick secondary walls. Their structural role does not require metabolic activity.
- Have thick, lignified walls.
- Possess a narrow lumen.
- Provide rigidity rather than physiological function.
10. What is the economic importance of plant fibres?
Plant fibres have major economic importance because they are used in textiles, ropes, paper, and eco-friendly materials. Their high tensile strength and biodegradability make them valuable natural resources.
- Textile industry – cotton and flax.
- Rope and packaging – jute and hemp.
- Mats and brushes – coir and sisal.
