The Structure of Leaves

Julia Wellons, Sophia Kinnear, Tyler Rathkamp, Andrew Zhang

Structures and Functions

Mesophyll- the green tissue in the interior of the leaf, chloroplasts are concentrated in the cells of the mesophyll

Stoma (Stomata)-these tiny pores are the way by which carbon dioxide enters the leaf, and oxygen exits

Vein- water is absorbed and by the roots and is delivered to the leaves in veins.

Chloroplast- The organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of arguing molecules from carbon dioxide and water.

Thylakoid-a disk shaped membranous sac inside the chloroplast. Thylakoid membranes contain chlorophyll and the enzymes of the light reactions of photosynthesis.

Granum- a stack of Thykaloids

Chlorophyll- a light-absorbing pigment in the chloroplasts that plays a central role in converting solar energy to chemical energy.

Sources of...

Water- water is absorbed by the roots of the plant from the ground, and is delivered to the leaves in veins

Carbon Dioxide- enters through the stomata on the underside of the leaf

Oxygen- Exhaled through the stomata

Leaf Differences

The pigments in leaves include chlorophyll and carotenoids. Chlorophyll absorbs light, while carotenoids have a variety of functions. Most absorb light blue and green light, which chlorophyll is bad at. A special group of carotenoids, called xanthophylls, typically donate electrons and dissipate heat.


The shape of a leaf is determined by balancing the need to dissipate heat and the need to have the largest surface area to capture the most sunlight. Leaves at the top of a tree tend to be thinner and smaller to better dissipate heat, and the thinness also allows light to pass completely through the leaf to let leaves below capture sunlight as well. The leaves at the bottom of a tree tend to be larger and thicker to better capture sunlight.


The climate affects leaves as because the shape of leaves depend on the amount of sunlight a leaf gets and the humidity of the air. Needle shaped leaves, like those of the evergreen, have a smaller amount of surface area to prevent water loss in dry winters, as well as a far thicker cuticle.

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