How Aquatic Plants Survive Underwater: Respiration & Rot Resistance

Question: How do water plants respire underwater? Why don't they rot like terrestrial plants submerged?

Gas Exchange

Submerged plants exchange gases (O₂, CO₂) directly through leaf surfaces via diffusion — slower than air, but sufficient. Many have thin, dissected leaves for surface area.

Rot Resistance

• Aerenchyma: Internal air channels transport O₂ from leaves to roots.
• Anaerobic metabolism: Tolerate low O₂ in roots.
• Antimicrobial compounds: Inhibit decay organisms.
• Root adaptations: Shallow, adventitious roots in oxygenated sediment layer.

Terrestrial plants lack these — roots suffocate, rot fungi invade.

Fascinating evolutionary engineering!