Question

An underground stem axis with swollen base and enclosed by dry scale like leaves is called as
A. Rhizome
B. Bulb
C. Sucker
D. Corm

Answer 1

Hint: A stem is the main ascending axis of a plant that develops from the plumule and epicotyl of the embryo. It bears leaves, branches, flowers and fruits. It has nodes and internodes that distinguish it from other underground plant parts.

Complete answer:
Rhizome is a perennial underground main axis of the plant that grows indefinitely below the soil surface producing aerial leaves or shoots above the ground and adventitious roots on the lower side in favorable season. They pronounce during the unfavorable season. Most of the rhizomes are fleshy and store reserve food materials. They are differentiated into nodes and internodes. The nodes bear brown scale leaves that protect axillary buds.
Sucker like runner develops from the nodes of the horizontal or vertical branch of the main stem. But it usually moves horizontally below the soil. It also develops from the axis of the scaly leaves from axillary buds. Adventitious roots develop from the lower side of nodes.
Some of the branches come above the soil obliquely and produce green leaves to form aerial shoots. So the sucker can be rightly called an underground runner, e.g. Chrysanthemum and Mentha. Some authors consider mint as a runner. Sucker is shorter and stouter than a runner.
Bulb is the type of modification in which the stem is reduced to form a disc. The bulb is also unbranched and it stores food. Adventitious roots are present at the base of the reduced stem to keep the bulb vertical in the soil. The branches are absent and the examples of bulb are onion and garlic.
Corm is a condensed, fleshy solid and vertically growing root stock with a large apical bud. It is usually unbranched. The shape of the corm is almost spherical or somewhat flattened from top to bottom due to excessive deposition of food material, for example, Crocus sativus.
So, the correct answer is “Option D”.

Note: Stems of flowering plants attain diverse forms in order to perform their various functions. Basically they are grouped under three broad categories- reduced stem, erect stem and weak stems.