Secondary xylem and phloem in dicot stem are produced by

What is correct for heartwood?

In this organ,the vascular cambium is initially wavy and later becomes circular.

The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood.
$(a)$ It is also called as the earlywood
$(b)$ In spring season cambium produces xylem elements with narrow vessels
$(c)$ It is lighter in colour
$(d)$ The springwood along with autumnwood shows alternate concentric rings forming annual rings
$(e)$ It has lower density
Choose the correct answer from the options given below:

Seasonal activity of vascular cambium is influenced by many factors,except

Grafting is successful in dicots but not in monocots because the dicots have