Tyloses,an outgrowth from ray or axial parenchyma cells into the lumen of a vessel,which partially or completely blocks the cavity,are present in:

The wood is,in fact,a

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.

Old trees obtain $O_2$ from

Give a scientific reason: Grafting is not possible in monocots.

Vascular cambium in dicot root develops from