SC.3.L.14.2: Plants Response to Stimuli

What Are Seeds?

When a seed is produced by a plant, it needs warmth and water to begin growing. If a seed falls to the ground in the cool dry season, it will not start growing until temperatures warm and rains start to fall. The seed responds to the heat and moisture of the rainy season by germinating or beginning to grow.

Inside every seed is a miniature plant ready to grow. The seed contains the parts to make a root and a stem, and some seeds contain the plants first leaves. When the seed germinates, the seed responds to the pull of gravity by growing the root down into the ground. The germinating plant responds to the light of the Sun by lifting the stem and leaves up. The stem and leaves grow up in response to the Sun’s light, and the roots grow down in response to gravity. 

This mangrove seed to the right has already started to grow before it even falls form the tree. The root is already growing down in response to gravity.