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
blade
petiole

3. Mesophyll is between the leaf’s dermal tissue layers.
cuticle
upper
epidermis
palisade mesophyll
spongy mesophyll
lower epidermis

4. 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.
guard cells
stoma

5. Leaves may be simple, compound, or double compound.
Simple leaf
Compound leaf
Double compound leaf

6. Leaf veins may be parallel or pinnate.
Pinnate veins
Parallel veins

7. Leaf margins may be toothed, entire, or lobed.
Toothed margin
Entire margin
Lobed margin

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
xylem
phloem
cuticle
upper
epidermis
palisade mesophyll
spongy mesophyll
stomata
lower epidermis

9. Leaves have many adaptations.
for extreme temperatures, ex: pine needles

10. Leaves have many adaptations.
for extreme temperatures, ex: pine needles
for water loss, ex: cactus spines

11. Leaves have many adaptations.
for extreme temperatures, ex: pine needles
for water loss, ex: cactus spines
for aquatic environments, ex: water lily

12. 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