What is meant by secondary growth ? Which are its type ?
$\rightarrow$ Primary Growth : With the help of lateral meristematic tissue, length of root and stem grows. It is called primary growth.
$\rightarrow$ Secondary Growth : After completion of primary growth, mainly dicot plants thicken. This increase in thick thickening is called secondary growth.
$\rightarrow$ Types of secondary growth : Two types of lateral meristem take part in secondary growth. Vascular cambium and cork cambium.
Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality ? Explain in detail.
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:
$A$ : Oldest layer of sapwood lies just outside vascular cambium.
$R$ : Sapwood contains actively conducting vessels and occupies central part of stem.
Which tissue gives rise to secondary growth?