List and explain the elements of phloem tissue
Answers
Explanation:
seive tubes
companion cells
pholem parenchyma
phloem fibres
Explanation:
The Sieve Elements
The sieve elements are elongated and narrow cells that are connected together to form the phloem’s sieve tube structure. They are considered the highly specialized types of cells that are found in plants. These elements lack the nucleus at maturity and are also lacking in organelles such as ribosomes, cytosol, and Golgi apparatus, to maximize the available space for the translocation of materials.
Sieve Plates
Sieve plates are located in between the connections of sieve member cells, which are modified plasmodesmata. They are large and thin in structure, these are the areas of pores that help to facilitate the exchange of materials between the element cells.
The Companion Cells
Each of the sieve element cells is closely associated with a ‘companion cell’ in angiosperms cell’ or an albuminous cell in gymnosperms. Companion cells consist of a nucleus, that is filled with dense cytoplasm. The cytoplasm is made up of numerous ribosomes and mitochondria. Due to this reason the companion cells are responsible for performing several metabolic reactions and other cellular functions.
Phloem Parenchyma
The parenchyma is a collection of cells, which make up the ‘filler’ of plant tissues. They have thin and flexible walls that are made of cellulose. The parenchyma’s main function that is present in the phloem is the storage of starch, fats, and proteins and in the case of some plants, they help in the storage of tannins and resins also.
Phloem Sclerenchyma
The sclerenchyma is the main tissue of the phloem that provides support, stiffness, and strength to the plant. Sclerenchyma comes in two forms: fibers are usually dead upon reaching maturity and are characterized by a thick secondary cell wall.