Answer:
Plant tissues have several types of cells i.e vessel elements and tracheids (in xylem),sieve tube cells and companion cells (in phloem) ,parenchyma cells,collenchyma cells and sclerenchyma cells.
Explanation:
Xylem is made up of vessel elememts and tracheids.
Vessel elements have thick secondary cell walls.They lack end walls and join together to form long tubes.
Tracheids are slender cells with overlapping ends.
Phloem is made up of sieve tube cells and companion cells.
Sieve tube cells are long and their end walls have small pores.
Companion cells make proteins for sieve tube cells.
Parenchyma cells are spherical but flat at point of contact.They have thin primary cell walls and have large vacuole for storage of food.In leaves they are called mesophyll cells and are the sites for photosynthesis.In other parts they are sites of respiration and protein synthesis.
Collenchyma cells are fexible and function to support the organs in which they are found.
Sclerenchyma cells contain rigid secondary cell walls.Their cell walls are hardened with lignin which is the main chemical component of wood.
