What Makes a Plant Bend Toward the Light?

Scientific research indicates that a certain class of plant hormones lead to the growth of plants toward a light source.

Phototropism

The growth of a plant toward a light source is called phototropism.

Postive Phototropism

Positive phototropism refers to plant growth toward a light source.

Negative Phototropism

Negative phototropism refers to plant growth in a direction opposite of a light source.

Explanation

Plants such as grasses typically grow toward a light source because cells on the dark side of the stem grow longer at a quicker rate than the cells on the same side as a light source, due to a skewed distribution of a plant hormone called auxin.

Auxin Definition

The term "auxin" refers to any chemical substance that supports the growth of the coleoptile, which is the sheath that covers a grass seedling shoot. ("Auxin" comes from a Greek word meaning "to increase.")