The Parts of the Leaf
Introduction to Photosynthesis

Up Close with a Leaf…
Important Parts:
Epidermis/Cuticle
Stoma and Guard Cells
Vascular Bundle
Spongy Mesophyll

Epidermis/Cuticle
• The epidermis is an outer layer of cells that protects the plant. It is coated with a cuticle, a waxy covering that surrounds a plant. It helps keep water in the plant – thus preventing it from wilting!
Cuticle
Epidermis

Stoma and Guard Cells
• Stoma are openings on the underside of a leaf that allow gas to pass in and out of the leaf. To prevent water loss stoma are surrounded by guard cells that open and close the stoma.
• On the left is a picture of an open stoma while the right shows a closed stoma.

Vascular Bundles: Composed of two parts
• Xylem cells form tubes that bring water from the roots to the rest of the plant.
• Phloem cells form tubes that bring food from the leaves to the rest of the plant.
Vascular
Bundle

Mesophyll Cells
• Mesophyll cells are cells inside of the leaf that contain numerous chloroplasts

Chloroplasts
• Chloroplasts are the organelle in plant cells responsible for converting light energy into chemical energy.

Chloroplasts: Three important parts
• The thylakoid converts light energy to chemical energy. This is where CHLOROPHYLL is located!
• Thylakoids are stacked like pancakes in stacks known collectively as grana (granum) .
• Area of the chloroplast outside of the thylakoid is called the stroma .
(Notice the ‘r’. Do not mix this up with the stoma .)