[IB Plant Science at GHS]

External Structure of the Leaf

of a Typical Dicotyledonous Plant

a. Increase surface area for Photosynthesis.

b. Gas exchange (CO2 in, O2 out).

c. Site of transpiration, evaporation of water that helps pull water up from roots.

Leaf Blade: Wide flattened area of leaf for concentrating sunlight on photosynthetic cells.

Petiole: Short stem that attaches leaf to main stem or branch.

Veins: Vascular bundles within leaf for transort.

Node: Growth region of stem where leaves or new branches arise.

Axillary bud: Baby leaf or stem (next years growth).

[Internal Features of the Leaf]