SECONDARY
GROWTH IN DICOT STEM.
•The
growth in length of main axis by the activity of apical meristem is called primary
growth.
Increase in thickness of the axis due to the formation of secondary tissue is
called secondary
growth.
•Secondary
growth occurs only in cortical region and it occurs only In dicot stem and
root.
MAIN
STEPS IN SECONDARY GROWTH
1.Formation of cambium ring.
2. Formation of secondary vascular
tissue.
3. Formation of secondary phloem.
4. Formation of secondary xylem.
5. Formation of vascular rays.
6. Formation of Annual ring.
SPRING
WOOD
AND AUTUMN WOOD.
•SPRING WOOD: In the spring season or early summer,
the cambium becomes more active and produces a large number of vessels with
wider cavities. These are called spring wood or early wood.
•The
spring wood is lighter in colour and has a lower density.
•AUTUMN WOOD:
During the autumn or winter season, the cambium becomes less active and
produces vessels with narrow cavities. Tracheids and wood fibres are forms in large
numbers. These wood are called autumn wood late wood.
•
