27
Give one basic functional difference between phellogen and phelloderm.
Explanation
Phellogen is a meristematic tissue, while phelloderm is a permanent tissue. Phellogen (cork cambium) develops from the cortical cells, sometimes from pericycle cells. These cells actively divide and forms phellem on outerside and phelloderm (cortex cells)innerside on so phelloderm takes its origin from phellogen.
28
Arrange the following in the sequence you would find them in a plant starting from the periphery-phellem, phellogen, phelloderm.
Explanation
Phellem or cork is the outer most layer, followed by phellogen (cork cambium) which in turn is followed by phelloderm (secondary cortex).
29
If one debarks a tree, what parts of the plant is being removed?
Explanation
Debark means the removal of bark, i.e., all tissue exterior to the vascular cambium, including secondary phloem. Bark refers to a number of tissue types, viz., periderm (phellogen, phellem and phelloderm) and secondary phloem.
30
The cross-section of a plant material showed the following features when viewed under the microscope.
(a) The vascular bundles were radially arranged.
(b) Four xylem strands with exarch condition of protoxylem. To which organ should it be assigned?
Explanation
Root is the organ which shows the features given in the question. Vascular bundles are present on separate radii thus called radial arrangement. Protoxylem is towards periphery of root thus making exarch condition.
31
What do hardwood and softwood stand for?
Explanation
Distinguish between softwood and hardwood is as
| Softwood | Hardwood |
|---|---|
| Gymnospermic wood is soft wood It chiefly contains trachieds Vessels are absent. |
Angiospermic wood is hard wood It chiefly contain both trachieds and vessels Trachieds are absent. |