Secondary growth, significance , vascular cambium, annual rings, sap & heart wood , Callus
Channel: biology by imran
Date: 2020-04-24

here a complete description about secondary growth in plant is given with animation to covers all of your doubts 

secondary growth
vascular cambium
primary xylem
primary phloem
 secondary xylem
secondary phloem
annual rings
sap wood
heart wood
support of xylem
callus
cork cambium
cork
bark