Anticlinal divisions in an organ cause its growth in

Which of the following is the function of heartwood?

Tissue commonly known as passport point or biological check post is characterised by

Tracheids differ from other tracheary elements in

Vascular tissue is well developed in

$I.$ Found only in sporophytic phase of life cycle

$II.$ May contain enzymes that are biologically active

$III.$ Often contain strengthening polymers

Select the correct option for cell wall