Leaves Flashcards
What are leaves?
Leaves are a lateral outgrowth from a plant and they are made up of a few basic parts.
Which are these basic parts?
There are two main basic parts that are shared by most leaves:
- Blade > The blade is the flat and broad expanded part of a leaf. It collects sunlight for the plant.
- Petiole > The petiole is a thin stalk that supports the blade of a leaf.
The axillary bud marks where a leaf ends.
What is about the leaf tissues?
Outer covering of a leaf:
Dermal tissue
Internal system of a leaf:
Vascular tissue surrounded by ground tissue
Between the two dermal layers of the dermal tissue of a leaf is a parenchyma tissue called mesophyll. The vascular tissues of xylem and phloem make up the veins that run throughout the mesophyll.
What are stomata?
Stomata are various small apertures in the epidermis of leaves, stems etc. where gas exchange and transpiration take place.
What is special about guard cells?
Guard cells surround each stoma and can open and close by changing shape. Potassium ions (K+) from neighboring cells accumulate in the guard cells. A high concentration of K+ causes water to flow into the guard cells as well.
What are the characteristics of a leaf?
Leaves may be simple with one blade connected to the petiole, but they can also be compound, with many blades on one petiole. Leaflets are multiple leaves. The leaf type, the vein pattern and the shape of the leaf margin (leaf edge) are important to identify leaves.
Which are the two types of mesophyll?
The two types of mesophyll are the spongy mesophyll and the palisade mesophyll:
- Palisade mesophyll > It is under the dermal layer and it has tall, rectangular cells that absorb much of the light that enters the leaf.
- Spongy mesophyll > It is beneath the palisade mesophyll. It has cells that are loosely packaged, creating many air spaces.
What is a cuticle?
A cuticle is a hyaline film covering the surface of plants. It protects the inner tissues and limits evaporation from the plant.
REMEMBER!
Leaves absorb light and carry out photosynthesis!
Most leaves share some similar structures!
Most leaves are specialized systems for photosynthesis!
