KEY CONCEPT Leaves absorb light and carry out photosynthesis.
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
Mesophyll is between the leaf’s dermal tissue layers. cuticle upper epidermis palisade mesophyll spongy mesophyll lower epidermis
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
Leaves may be simple, compound, or double compound. Simple leaf Compound leaf Double compound leaf
Leaf veins may be parallel or pinnate. Pinnate veins Parallel veins
Leaf margins may be toothed, entire, or lobed. Toothed margin Entire margin Lobed margin
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
Leaves have many adaptations. for extreme temperatures, ex: pine needles
Leaves have many adaptations. for extreme temperatures, ex: pine needles for water loss, ex: cactus spines
Leaves have many adaptations. for extreme temperatures, ex: pine needles for water loss, ex: cactus spines for aquatic environments, ex: water lily
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