Leaves

Functions Photosynthesis needs H2O and CO2

Structures

Structures

Structures Petiole Blade Stalk connecting leaf to stem Broad, flat portion of the leaf

Structures Cuticle Epidermis Waxy, waterproof layer on outer surface Outermost layer Non-photosynthetic and transparent

Structures Mesophyll Middle of leaf Cells contain chloroplasts; photosynthetic cells Vascular bundles (veins) are embedded

Structures Mesophyll

Mesophyll Two types of cells… Palisade cells Layer of columnar cells just beneath the upper epidermis Most photosynthesis occurs here Spongy Cells Layer of irregular shaped cells just above the lower epidermis Spaces between cell to aid in gas exchange

Structures Veins Vascular system in leaves Xylem: Phloem: hollow tubes with thick walls that carry water; in outside part of veins Phloem: carry food materials in solution from the leaves to other parts Inside part of vein

Structures Stromata Adjustable pores which regulate the diffusion of CO2 and H2O

Structures Guard Cells Pair of cells that regulate gas and water exchange with the air

Leaf Questions Read pages 535-540 and answer the following questions on a separate piece of paper: What is the primary role of leaves? What tissue prevents a leaf from injury or drying out? What are the veins of a leaf composed of? What are the three important functions of veins? Distinguish between the spongy layer and the palisade layer. A) What are the stromata? B) What leaf structures adjusts the stromata’s size? C) What is the function of these structures? 7. Compare monocot and dicot leaves.