A plant that commonly undergoes vegetative propagation by means of leaves is

Analyze the question: We need a plant that reproduces vegetatively (asexually, without seeds or spores) using its leaves.

Concept: Vegetative propagation is when new plants grow from a part of the parent plant, such as stems, roots, or leaves. Different plants use different organs:

• Stem: sugarcane, cassava (stem cuttings), Irish potato (stem tuber)
• Root: sweet potato (root tuber)
• Leaf: Bryophyllum (also spelled Bryophylum), sometimes called "resurrection plant" or "never-die" plant

Going through the options:

• A. Hibiscus: Usually propagated by stem cuttings or seeds, not leaves.
• B. Bryophylum: The leaf margins have notches that produce tiny plantlets (adventitious buds). These drop to the soil and grow into new plants. This is the classic example of leaf propagation.
• C. Crotalaria: A leguminous plant that reproduces by seeds.
• D. Spirogyra: A filamentous green alga that reproduces by fragmentation (and conjugation sexually). It has no true leaves.

Answer: The correct option is B. Bryophylum.

Exam tip: Memorize the "organ → example" pairs for vegetative propagation:

• Leaf → Bryophyllum
• Stem tuber → Irish potato
• Root tuber → Sweet potato
• Rhizome → Ginger
• Bulb → Onion
• Sucker/stem cutting → Banana, cassava, sugarcane

If you see "leaf" and "vegetative propagation" together, think Bryophyllum immediately.