[IB Plant Science at GHS]

Internal Structure of the Leaf

of a Typical Dicotyledonous Plant

Internal Leaf Structure

a) Cuticle: Waxy layer water proofing upper leaves.

b) Upper epidermis: Upper layer of cells. No chloroplasts. Protection.

c) Palisade Mesophyll: Tightly packed upper layer of chloroplast containing cells.

d) Spongy Mesophyll: Lower layer of chloroplast containing cells. Air spaces around them.

e) Lower Epidermis: Lower external layer of cells in leaf.

f) Vascular Bundle: Bundle of many vessels (xylem and phloem) for transport.

g) Xylem: Living vascular system carrying water & minerals throughout plant.

h) Phloem: Living vascular system carrying dissolved sugars and organic compounds throughout plant.

i) Guard Cells: 2 cells surrounding stomata that control rate of gas & water exchange.

j) Stomata: Opening between guard cells for gas & water exchange. (See Diagram below.)

[External Features of the Leaf]

Long & Slichter