Companion cells in plants are associated with

Companion cells are specialized cells derived from $.........$.

Which of the following tissues does not possess specialized thickened cell walls?

Specialised parenchyma cells which store tannins,oils,and crystals of calcium oxalate are called:

Deciduous plants shed their leaves during hot summer or in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes,what anatomical mechanism is involved in the abscission of leaves?

What does callose block?