Leaves

leaf

large surface area that is exposed to sunlight and carbon dioxide for photosynthesis

leaf internal structure

• cuticle

• upper epidermis

• palisade mesophyll

• spongy mesophyll

• lower epidermis

• cuticle

• guard cells and stomata

cuticle

prevents water loss

mesophyll

parenchyma specialized for photosynthesis

palisade layer

exposed to direct sunlight

spongy mesophyll

loosely arranged cells in lower part of leaf (air sacs participate in gaseous exchange)

stomata

surrounded by two guard cells which open and close to regulate transpiration

• mostly located on lower epidermis, sometimes only found there (except floating aquatic plants like lilies)

vein

vascular bundle of xylem and phloem, form a network of movement of water, solutes, and photosynthetic products throughout the mesophyll

xylem vessels

transport water and mineral ions

phloem vessels

transport sucrose and amino acids

leaf shape

thin and flat to increase surface area for gas exchange