Question

Which type of vascular bundles are found in monocot stem?
A. Collateral, open, endarch
B. Radial, open, diarch
C. Radial, open, mesarch
D. Collateral, closed, endarch

Answer 1

Hint: Like the human body have capillaries and vessels for the transportation of important nutrients and minerals to every cell of the body, the plants also have specialised tissue that involve in the transportation process of the plants.

Complete Answer:
- Vascular tissue is the conductive tissue of plants in which multiple cells are arranged in such a way that it allows the transportation of minerals, water, and photosynthetic products throughout the plants. The xylem and phloem are the two vascular tissues found in the plants. Xylem is a specialized tissue that involves in the water transportation and movement of nutrients from root to the tip of the leaves of a plant.
- The xylem is formed from hollow dead cells. The phloem is the vascular tissue that is involved in the transportation of photosynthetic products throughout the plants. In the phloem tissue, the sieve cells connected through a thin membrane termed as sieve plate. This forms a channel through which sugar is transported throughout the plant.
- The structure of the vascular tissue is different for both monocot and dicot plants, in monocot plants, the xylem and the phloem scattered throughout the tissue and in dicot plants, the xylem and the phloem are arranged in a ring that is also termed as cambium ring.
- The collateral vascular bundles are also observed in dicotyledons plants in which the cambium may or may not be present between the xylem and phloem patches that make the vascular bundle open or close respectively.
- If the cambium is present in between the xylem and the phloem then it is considered as an open collateral bundle and if cambium is not present between xylem and phloem it is considered to be closed.
- Now, the vascular bundles of the monocot stem are irregularly scattered in the ground tissue. The bundles are smaller in the periphery and larger in size towards the center. The smaller bundles are younger, while the larger ones are older. Therefore, the arrangement is described as endarch.
- Every bundle is covered with bundle sheath that is formed from a layer of sclerenchyma cells. The vascular bundle encloses both xylem and phloem. The xylem is present in the inner surface and phloem in the outer surface and cambium is not present in monocot plants. Hence, the vascular bundles in monocot stem are endarch, closed, and collateral.

Thus, the correct answer is ‘D’. Collateral, closed, endarch.

Note: In some monocot plants like palm, a secondary growth technique is used that maintains a scattered arrangement of the vascular tissue. The collateral vascular bundle is observed in all dicot plants except the member of Cucurbitaceae.