leaf structured
A leaf is structured with a blade (lamina) for photosynthesis, attached to the stem by a petiole
External parts
Blade (Lamina): The broad, flat part of the leaf that captures sunlight.
Petiole: The stalk that connects the leaf blade to the stem.
Veins: A network of vascular tissues that transport water, nutrients, and sugars, and provide structural support. The main vein is the midrib.
Stipules: Small, leaf-like appendages that may be found at the base of the petiole.
Apex: The tip of the leaf.
Margin: The edge of the leaf.
Internal parts
Cuticle: A waxy, waterproof layer on the surface of the leaf that reduces water loss.
Epidermis: The outer layer of cells that covers and protects the leaf.
Mesophyll: The inner tissue of the leaf, containing two layers:
Palisade mesophyll: Located at the top, these cells are packed with chloroplasts to maximize light absorption for photosynthesis.
Spongy mesophyll: Located below the palisade layer, this tissue has air spaces that allow for gas exchange between the cells and stomata.
Stomata: Pores, usually on the underside of the leaf, surrounded by guard cells that open and close to regulate the intake of carbon dioxide and the release of oxygen and water vapor.
Vascular bundles: Also called veins, these contain xylem (for water transport) and phloem (for food transport).