Question

The monocot stem lacks
A. Tracheids
B. Sieve tube
C. Cambium
D. None of the above

Answer 1

Hint: Monocot stem is a loop-shaped hollow axial portion of the plant that causes internodes, nodes, branches, leaves, and flowers with roots at the basal end. The size of stems varies by species of monocots, but the size is just ever as big as dicots.

Complete step-by-step answer:
The monocot stem is usually hollow at the centre. Monocot stems have most of their vascular bundles close to the external edge of the stem. The bundles are encircled by the huge parenchyma in the cortex region. There is no pith area in the monocots. In the monocot stem, vascular bundles comprise both xylem and phloem. Phloem lies towards the exterior and the xylem on the inside. Cambium is not present as the whole procambium is consumed in the development of vascular tissues. Thus, the vascular bundles are conjoint, collateral but closed. Phloem comprises companion cells, sieve tubes, and a few phloem fibres. Phloem parenchyma is not present. Xylem is composed of tracheids, vessels, xylem parenchyma, and a few xylem fibres.

Hence the correct answer is Cambium.

Note: The monocot stems do not contain trichomes. It mostly consists of rigid, organised, rectangular cells covered with a waxy substance called cutin. The internal structure of a monocot stem mostly encompasses a well-developed ground tissue, hypodermis, epidermis, and several dispersed vascular bundles. Examples of monocot stems are lilies, onions, tulips, and garlic. The vascular bundles are dispersed irregularly around the ground tissue. The monocot stem contains a sclerenchymatous bundle sheath on the exterior side of a vascular bundle.