explain phloem tissue in detail
Answers
Phloem
→ They also consist of both parenchymatous and schlerenchymatous cells.
→ Phloem consists of four types of element which are Sieve tubes, Companion cells, Phloem fibre and Phloem parenchyma.
(i) Sieve tubes
→ Sieve tubes are slender tube like structures made up of elongated, thin walled cells placed end to end.
→ The end walls of sieve tube cells are perforated by numerous pores, called as sieve plates.
→ Nucleus of sieve cell degenerates at maturity. However, cytoplasm persists, because of protoplasmic continuation of sieve tube with companion cell through plasmodesmata.
→ Sieve cells possess slime protein or protein which is concerned with growth and repair of sieve cells.
(ii) Companion cells
→ Companion cells have dense cytoplasm and prominent nuclei.
→ Sieve cells & companion cells are so called sister cells because they originate from single mother cell.
(iii) Phloem fibre
→ They give mechanical support to sieve tubes.
(iv) Phloem parenchyma
→They store food and help in radial conduction of food.
(v) Leptome
→ Main part of phloem involved in conduction of food, which is sieve tube.
→ In xylem, only unidirectional movement is possible while in phloem bidirectional movement can occur.
→ In phloem, except phloem sclerenchyma all elements are living.
Explanation:
Refer to the attachment....
