secondary growth in dicot stem

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.

 

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