Long Answer TypeExplain the process of secondary growth in the stems of woody angiosperms with the help of schematic diagrams. What is its significance?
Draw illustrations to bring out anatomical difference between:
(a) Monocot root and dicot root
(b) Monocot stem and dicot stem
Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or a dicot stem? Give reasons.
Short Answer TypeThe transverse section of a plant material shows the following anatomical features:
(a) the vascular bundles are conjoint, scattered and surrounded by a sclerenchymatous bundle sheaths.
(b) phloem parenchyma is absent. What will you identify it as?
Long Answer TypeShort Answer TypeName the three basic tissue systems in the flowering plants. Give the tissue names under each system.
Long Answer TypeWhat is periderm? How does periderm formation take place in the dicot stems?
Periderm is composed of the phellogen, phellem, and phelloderm.
During secondary growth, the outer epidermal layer and the cortical layer are broken because of the cambium. To replace them, the cells of the cortex turn meristematic, giving rise to cork cambium or phellogen. It is composed of thin-walled, narrow and rectangular cells.
Phellogen cuts off cells on its either side. The cells cut off toward the outside give rise to the phellem or cork. The suberin deposits in its cell wall make it impervious to water. The inner walls give rise to the secondary cortex or phelloderm. The secondary cortex is parenchymatous.
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