KEY CONCEPT Leaves absorb light and carry out photosynthesis.

1
KEY CONCEPT Leaves absorb light and carry out
photosynthesis.
2
Most leaves share some similar structures.

• The blade is usually broad and flat.
• collects sunlight for photosynthesis
• connects to the stem by a petiole

3

• Guard cells surround each stoma.

• Stomata open and close when guard cells change
  shape.
• When stomata are open, water evaporates and gas
  exchanges.
• Stomata close at night and when plant loses too
  much water.

4

• Leaves may be simple, compound, or double
  compound.

5

• Leaf veins may be parallel or pinnate.

6

• Leaf margins may be toothed, entire, or lobed.

7

• Mesophyll is between the leafs dermal tissue
  layers.

8
Most leaves are specialized systems for
photosynthesis.

• There are two types of mesophyll cells.
• both types contain chloroplasts
• palisade mesophyll absorbs sunlight
• spongy mesophyll connects to stomata

9

• Leaves have many adaptations.

• for extreme temperatures, ex pine needles
• for water loss,ex cactus spines

• for aquatic environments, ex water lily

• for getting food,ex Venus flytrap