Xylem vs Phloem: Differences in Structure and Function

Xylem

• Transports water and dissolved minerals from roots to leaves (upward)
• Consists of: tracheids, vessels, xylem parenchyma, xylem fibres
• Vessels and tracheids are dead at maturity (no cytoplasm)
• Transport is unidirectional (only upward)
• Driven by transpiration pull (passive, no energy needed)
• Located towards the centre of the vascular bundle

Phloem

• Transports food (sucrose, amino acids) from leaves to all parts (translocation)
• Consists of: sieve tubes, companion cells, phloem parenchyma, phloem fibres
• Sieve tubes are living (but no nucleus — companion cells control them)
• Transport is bidirectional (up and down depending on need)
• Requires metabolic energy (ATP) — active process
• Located towards the outside of the vascular bundle

Key Differences

• What: Xylem = water + minerals, Phloem = food (organic)
• Direction: Xylem = upward only, Phloem = bidirectional
• Cells: Xylem = dead, Phloem = living (sieve tubes)
• Energy: Xylem = passive, Phloem = active (needs ATP)
• Position: Xylem = inner, Phloem = outer in vascular bundle