How Do Plants Absorb Food Coloring?

Plants can absorb harmful substances in the same way as they do colored water.

A plant's stems contain passageways that allow water to travel from its roots to its leaves and flowers. Adding food coloring to the water illustrates the path it takes on its journey to the flowers, where it eventually deposits its pigments.

How It Works

Water molecules pass directly through the walls of the plant's hair-like roots and immediately make their way up through the xylem, or the tiny pipelines that run the length of its stem. In this way, colored water travels to the plant's leaves and stems and is stored briefly in tiny pores called stomata.

Plant Plumbing

In a system of water displacement, water that moves up into plant through its roots replaces what is lost through transpiration, or the giving off of water into the atmosphere. As colored water reaches the plant's flowers, the water is released by the stomata but the coloring remains in the petals and along some of the leaf veins. Cutting the plant's stem also reveals food coloring around the edges of the xylem.

Effects

Tinting plants with food coloring works best on plants with pale or white flowers, such as Queen Anne's Lace or white carnations. According to the MadSci Network, red or blue coloring works best, and it takes about six to 12 hours for a white flower to show the full effects of the food coloring.

References

• University of Bristol: Water Transport Through Plants
• MadSci Network: Coloring Flowers
• Steve Spangler Science: Color Changing Carnations