A plant with short, vertical underground stem is a

Step 1: Analyze the question The question asks which type of modified underground stem is short and vertical (upright).

Step 2: Explain the concepts Underground stems are modified for food storage and vegetative propagation. The main types are:

• Bulb: A very short, flattened stem with fleshy scale leaves that store food (e.g., onion, garlic). The stem is reduced to a small disc, and the storage is in the leaves.
• Corm: A short, thick, vertical, swollen underground stem that stores food in the stem itself (e.g., cocoyam, gladiolus, crocus).
• Rhizome: A long, horizontal underground stem, often with nodes and internodes (e.g., ginger, spear grass, turmeric).
• Tuber: A swollen tip of an underground stem branch, with "eyes" (e.g., Irish potato, yam, which is often treated as a stem tuber).

Step 3: Apply to the question The key phrases are "short" and "vertical":

• Rhizome is horizontal, so it is out.
• Tuber is a swollen, irregular stem tip, not described as vertical, so it is out.
• Bulb is a short stem, but its food is stored in fleshy leaves, and the stem is reduced to a disc. The description "short, vertical underground stem" better fits a corm.
• Corm is a short, thick, upright underground stem. It fits perfectly.

Step 4: Answer The correct answer is B. corm.

Tip: Remember the direction and shape:

• Rhizome = Runs sideways (horizontal)
• Corm = Compact and upright (short, vertical)
• Bulb = Big fleshy leaves around a tiny stem
• Tuber = Tip of the stem swollen (potato)

Cocoyam is the classic Nigerian example of a corm, so it is easy to remember.