Which of the following tissues originate from ray initials of a cambium
Vascular rays
Tracheids and vessels
Xylem and phloem fibres
Sieve tube and companion cells
Select the wrong statements
$I.$ Primary and secondary phloem gets crushed during secondary growth
$II.$ During secondary growth, primary xylem remains more or less intact
Give differences : Heartwood and Sapwood
Growth rings $(annual\ rings)$ are formed by activity of
Give explantion about heartwood and sap wood.
Definitions / Explanation :
$(i)$ Early wood
$(ii)$ Late wood