Leaf Transpiration Science Project Idea

How Water Passes Out of the Leaves

Does water pass out equally well from all parts of the leaf? This question may be answered by the following experiment:

Water Evaporation Through Leaves Science Project Experiment

Remove several leaves from a plant. Cover the upper surface of some of the leaves and the lower surfaces of others with a thin layer of Vaseline. Examine after several hours. Which leaves have withered most? Conclusion?

Has the lower surface of the leaf any openings by which moisture escapes? To answer this question examine a bit of the membrane or epidermis stripped from the lower surface of a leaf.

The kidney-shaped cells (guard cells) on each side of the openings (stomata) absorb, in moist weather, moisture from the air and swell up like the inner tube of an automobile tire when filled with air, making the opening or stomata large. In dry weather they lose their moisture, collapse, and make the stomata smaller. Of what advantage is this to the plant? Plants that live in dry regions possess various devices for the prevention of excessive transpiration, such as hairy, or thick-skinned leaves, or the reduction of leaf surface.