## The Surface Area of Leaves

The surface area of leaves plays an important role in plant growth and photosynthesis. Photosynthesis is the process by which plants transform light (light energy) into food (chemical energy). Light, water, and carbon dioxide gas are all necessary for photosynthesis to occur. Light is absorbed by leaves and differences in surface area exposed to light can change the rates of photosynthesis. Cell structures involved in carbon dioxide exchange, called *stomates* or *stomata,* exist in proportion to a leaf’s surface area. Water also evaporates, or *transpires*, through the many stomata on the leaf surface. As such, the rate of transpiration is directly related to the surface area.

One method of measuring the surface area of leaves is known as the *grid method *or the* grid count method.* The grid method is useful for measuring a small quantity of leaves and is known for being highly accurate.

## Grid Method

- Print or draw graph paper with a 1-centimeter grid (search “1 cm grid paper template” for printable options).
- Carefully remove leaf from plant and place on grid paper.
- Trace the leaf’s outline and remove the leaf.

- 4. Count the number of squares that are completely within the outline.

- Estimate the areas partially covered – The simplest way to do this is: count a partial square if it is at least half covered by the leaf; do not count partial squares that are less than half covered.

- Add up the number of squares counted (fully filled + half full squares) and you now have the surface area of the leaf in centimeters squared (cm
^{2}).

*This activity was written by Jane Thaler, a Gallery Presenter in the museum’s LifeLong Learning Department.*