What is/are true about heartwood?

$I.$ It does not help in water conduction.

$II.$ It is also called alburnum.

$III.$ It is dark in colour but very soft.

$IV.$ It has tracheary elements, which are filled with tannin, resin, etc.

Bark refers to all tissues exterior to the

What is periderm? How does periderm formation take place in dicot stem?

During secondary growth of plants, stem phellogen cuts of cells on both sides. The outer cells gets differentiated into …$A$… and the inner cells gets differentiated into …$B$… cortex

Choose the correct combination of $A$ and $B$ with reference to above statement

The waxy substance associated with cell walls of cork cells is or cork cells are impervious to water because of the presence or what is deposited on cork cells