Question

Bulb of Allium cepa (onion) is

• A. underground modified bud with reduced discoid stem and without adventitious roots.
• B. underground shoot with reduced stem and fleshy leaves.
• C. both (1) and (2) correct.
• D. underground root.

Answer 1

Answer: (B)

Some plants adapt as the underground stem modification system in which stem that is derived from stem tissue exists under the soil surface, and one such example is a bulb.
The bulb has a highly condensed disc-like stem with its upper surface ends a terminal bud with fleshy scaly leaves. The adventitious roots arise from the lower region of the bulb with the presence of tunica (covering). A tunicated bulb is covered by a sheath of dry scale leaves, e.g., onion and garlic. In the case of garlic, the bulb consists of a group of bulblets or cloves, each covered by its individual dry scale leaves or tunic. Lily is an example of non-tunicated (no cover) scaly bulb.