Xylem and phloem are part of the vascular tissues in vascular plants. Phloem plays a role of transporting food materials referred to as photosynthate from photosynthetic organs to different parts of the plant in a process referred to as translocation. Just like xylem, phloem tissues can be classified as primary phloem and secondary phloem.
The primary phloem is on that originates from procambium and is responsible for primary growth (growth in length) of plants. On the other hand, secondary phloem is one that originates from vascular cambium during secondary growth (growth in girth). The primary phloem is usually located in the primary plant body parts and occurs towards the periphery. It is comprised of Metaphloem and protophloem together with sieve tubes and phloem parenchyma. Both Metaphloem and protophloem contain living and dead cells.
Metaphloem and Protophloem differ extensively both in structure and in terms of cellular components for example the sieve elements of Metaphloem are relatively longer, conspicuous and with a wider lumen when compared to protophloem.
Below get to understand in details, the difference and similarities between Metaphloem and protophloem in a primary vascular bundle of a young stem. The basis of comparison includes: Formation, sieve elements, cellular composition, size of constituent elements, and life cycle among others.
What You Need To Know About Protophloem
- It is the first formed phloem when the plant organ is growing.
- Composed of sieve elements, phloem parenchyma and fibres.
- In the protophloem the sieve elements are generally thin and inconspicuous.
- It is made up of smaller and narrower elements.
- Protophloem is short lived, become non-functional when the plant matures.
- The protoplasts of protophloem are conspicuously vacuolated and without nuclei.
- Protophloem is subjected to stress during elongation and maturation.
- In stem, protophloem is arranged towards the periphery.
- Companion cells are usually absent.
- Sieve areas inconspicuous and absent in gymnosperms.
What You Need To Know About Metaphloem
- It is the later formed phloem which differentiates when the plant organ has completed its growth.
- Composed of sieve elements, companion cells, phloem, parenchyma and phloem fibres.
- In Metaphloem, the sieve elements are wide, long and conspicuous.
- It is made up of longer and broader elements.
- Metaphloem remain functional for longer periods, in plants without secondary growth, the Metaphloem is the only conducting tissue for the food material.
- In Metaphloem, the protoplasts possess one or more nuclei, which usually disappear in mature sieve elements.
- Metaphloem is not subjected to stress during elongation and maturation.
- In stem, Metaphloem is usually arranged towards the inner side.
- Companion cells are usually present.
- Sieve areas are very distinct and well developed.
Protophloem And Metaphloem Diagram
Protophloem Vs Metaphloem In Tabular Form
|BASIS OF COMPARISON||PROTOPHLOEM||METAPHLOEM|
|Formation||It is the first formed phloem when the plant organ is growing.||It is the later formed phloem which differentiates when the plant organ has completed its growth.|
|Cellular Composition||Composed of sieve elements, phloem parenchyma and fibres.||Composed of sieve elements, companion cells, phloem parenchyma and phloem fibres.|
|Sieve Elements||The sieve elements are generally thin and inconspicuous.||The sieve elements are wide, long and conspicuous.|
|Size Of The Constituent Elements||It is made up of smaller and narrower elements.||It is made up of longer and broader elements.|
|Life Cycle||It is short lived, become non-functional when the plant matures.||It remain functional for longer periods, in plants without secondary growth, the metaphloem is the only conducting tissue for the food material.|
|Protoplasts||The protoplasts are conspicuously vacuolated and without nuclei.||The protoplasts possess one or more nuclei, which usually disappear in mature sieve elements.|
|During Elongation And Maturation||It is subjected to stress during elongation and maturation.||It is not subjected to stress during elongation and maturation.|
|Arrangement In Stem||In stem, it is arranged towards the periphery.||In stem, it is usually arranged towards the inner side.|
|Companion Cells||Companion cells are usually absent.||Companion cells are usually present.|
|Sieve Area||Sieve areas inconspicuous and absent in gymnosperms.||Sieve areas are very distinct and well developed.|
What Are Some Of The Similarities Between Metaphloem And Metphloem?
- Both Metaphloem and Protophloem originate from the primary meristem and procambium.
- Both conduct water and food materials.
- Metaphloem and protophloem contain living and dead cells.
- They both complex tissues composed of many types of cells.
- They both develop in the primary vascular bundles.
You May Also Read:
- Difference Between Phloem And Xylem Cells
- Difference Between Parenchyma, Collenchyma and Schlerenchyma
- Difference Between Primary Xylem And Secondary Xylem
- Difference Between Protoxylem and metaxylem