The key difference between bordered pit and simple pit is that bordered pit has a secondary wall overarching the pit cavity forming a border while simple pit does not have an arching of the secondary wall and narrowing of the pit towards the lumen.
A pit is a thin depressed portion of the secondary cell wall. Pits are used to exchange fluids and communicate with neighbouring cells. Generally, two pits are located opposite to each other as a complementary pair. There are three main parts of a pit. They are pit chamber, pit aperture, and pit membrane. Pits are a characteristic feature of xylem in vascular plants. During the development of a pit, secondary cell wall may over arch the pit cavity, forming a border. Pits with such borders are called bordered pits. Pits without borders are called simple pits.
CONTENTS
1. Overview and Key Difference
2. What is Bordered Pit
3. What is Simple Pit
4. Similarities Between Bordered Pit and Simple Pit
5. Side by Side Comparison – Bordered Pit vs Simple Pit in Tabular Form
6. Summary
What is Bordered Pit?
A bordered pit is a type of pit that has a border. The border is formed due to the arching of the secondary cell wall over the pit cavity. Therefore, the bordered pit becomes narrow like a funnel towards the lumen of the cell. Bordered pits have pit apertures which are small rounded mouth-like parts. Pit apertures may have different shapes; circular, lenticular, linear or oval. When observed under the microscope, the bordered pit appears as a doughnut.
Figure 01: Bordered Pit
Bordered pits are abundant in vessels of many angiosperms and in the tracheids of many conifers. There are three main types of bordered pits in vessel walls of angiosperms. They are scalariform, opposite and alternate.
What is Simple Pit?
A simple pit is a pit that lacks a border. It is a type of pit found in plant cells such as parenchyma cells, medullary rays, phloem fibres, companion cells, and tracheids of several flowering plants.
Figure 02: Simple Pit Pair
Simple pits do not have arching of the secondary cell wall over the pit cavity. Therefore, there is no narrowing of the pit cavity towards the lumen of the cell. Pit cavity remains the same diameter. Sometimes, simple pit integrates with a bordered pit.
What are the Similarities Between Bordered Pit and Simple Pit?
- Bordered pit and simple pit are two types of depressions on the plant secondary cell walls.
- They exist as pairs; they located opposite to each other as a complementary pair.
- They act as channels for the transport of water and minerals between cells.
- Both have a pit chamber, a pit aperture, and a pit membrane.
What is the Difference Between Bordered Pit and Simple Pit?
The bordered pit has a border formed due to the overarching of the secondary cell wall while simple pit lacks a border. Thus, this is the key difference between bordered pit and simple pit. Moreover, in bordered pits, narrowing of the pit towards the lumen of the cell can be seen while there is no such narrowing in the simple pit.
Below tabulation shows more comparisons related to the difference between bordered pit and simple pit.
Summary – Bordered Pit vs Simple Pit
A pit is a depression of the secondary cell wall of a plant cell. Simple pits and bordered pits are two types of pits. In bordered pits, the secondary cell wall arches over the pit cavity while in simple pits, there is no such arching of the secondary cell wall over the pit cavity. So, this is the key difference between bordered pit and simple pit. Moreover, bordered pits are found in hardwood vessels, tracheids, and fibres while simple pits are found in parenchyma cells, in extraxylary fibres, and in sclereids.
Reference:
1. “Simple & Bordered Pits: Torus Margo Structure | Easy Biology Class”. Easybiologyclass.Com, 2020, Available here.
2. “Pit Pairs: Structure And Types | Biology (777 Words)”. Your Article Library, 2020, Available here.
Image Courtesy:
1. “Image from page 41 of “Botany for high schools and colleges” (1885)” By Internet Archive Book Images (No known copyright restrictions) via Flickr
2. “Simple Pit Pair” By Pagliaccious – Own work (CC BY-SA 4.0) via Commons Wikimedia
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