What is the difference between fibers and sclereids?
Plant cells tend to comprise of parenchyma, collenchyma, and sclerenchyma. These tissues tend to have different structural and functional properties to the plants. Sclerenchyma tissue is meant for offering mechanical support due to the lignin properties. It is further divided into fibres and sclereids.
The lesson discussion provides detailed insight into the difference between fibres and sclereids with a comparison table. You will be able to differentiate the function of sclereids and fibers to the plant cell.
What Are Fibres?
Fibres are thick, elongated and spindle-shaped cells with pointed tips. They normally occur in bundles and there end walls are tapering. These cells are rich in lignin and pits along with the elongated cells.
The core function of the distributed fibers cells in the plant is to offer mechanical support to the plants. The structure of the fibres varies depending on the type of plant. These cells are further classified into:
Xylary Fibres
These are fibres which are linked to xylem. They are further subdivided into libriform fibres, fibre tracheids, septate fibres and mucilage fibres. Libriform fibres are marked by long and simple pits while fibre tracheids consist of short with bordered pits. Septate fibres have cross-walls in the fibre cell while mucilage fibres consist of a gelatinous layer.
Extra-xylary Fibres
These are fibres associated with tissues apart from xylem. They are further subdivided into phloem fibres, pericyclic/perivascular fibres, and cortical fibres. Phloem fibres are linked to phloem tissue while pericyclic fibres are found in dicot stem with close proximity to vascular bundles. Cortical fibres originate from the cortex and found in the stem.
Characteristics of Fibres
- Have tapering end walls
- Tend to be unbranched
- Have elongated cells
- Originated from meristematic cells
- Occur in bundles
What Are Sclereids?
Sclereids are sclerenchyma cells with highly lignified and thick cell walls with a narrow lumen. They have multiple layers to offering mechanical support to the plants. They have variable shapes and have simple pits.
However, they are further divided into five classes depending on the size and shape of the cell. These classes include:
Brachysclereids: They are also known as stone cells. They are located in the cortex, phloem, and pith. They are said to have an elongated shape. They are common in the flesh of fruits such as Guava and endocarp region of apple.
Macroscleroids: They have the rod-shaped appearance and they are known in the formation of palisade cells in the seed coat of legumes plant.
Osteoscleroids: They have columnar shape and are well distributed in the sub-epidermal layer of the seed coats.
Astrosceleroids: They are mostly found in the leaf surface and they are termed as an extension of the cell structure
Trichoscleroids: They have thin walls and branched. They are also located in the leaf surface
Characteristics of Sclereids
- They are broad
- Have blunt end walls
- Occur in loose groups
- Have deep pits which are straight
- Provide stiffness
Comparison Chart: Fibres Vs Sclereids
| Basic Terms | Fibres | Sclereids |
| Description | Have a thick, elongated, spindle shape with pointed tips | Have highly lignified thick cell walls having a narrow lumen |
| Shape | Elongated cells | Broad cells with irregular shape |
| End Walls | Tapering | Blunt |
| Branching | Branched | Either branched or unbranched |
| Origin | From meristematic cells | Parenchyma cells |
| Organization | Occur in bundles | Loose groups |
| Occurrence | Cortex, pericycle, xylem, and phloem | Cortex, pith, pulp of fruits, and fruit walls |
| Function | Provides mechanical strength | Provides stiffness |
Core Differences between Fibres and Sclereids
- Fibres are elongated while sclereids are broad
- The end walls of fibres are tapering while those of sclereids are blunt
- Fibres are generally unbranched while those of sclereids are either branched or unbranched
- Fibres originate from meristematic cells while sclereids originated from parenchyma cells of secondary thickening
- Fibres offer mechanical support while sclereids offer stiffness
- Fibres are found in the cortex, pericycle, xylem, and phloem while sclereids are found cortex, pith, pulp, and fruit walls
- Fibres occur in bundles while sclereids occur as loose groups
- Fibers have a spindle shape while sclereids have an irregular shape
- The pith of fibres is oblique while that of sclereids is straight
Similarities between Fibres and Sclereids
- Both are sclerenchyma cells
- Both cells are lignified
- Both provide mechanical support to plants
- Both are located in the phloem and xylem tissues
Comparison Video
Summary
The core difference between fibres and sclereids is the shape. Fibres have elongated with spindle shape while sclereids are broad with an irregular shape. However, they are both sclerenchyma cells which provide mechanical support to the plant.