Key Ideas

• Every plant is built from three basic parts: roots, stem, and leaves.
• Those parts come in an enormous variety of shapes and sizes. Each variation is called a modification.
• Apparent exceptions usually are not. A pine needle and a lily pad are both leaves, and grass has a stem so short it is easy to miss.
• Roots come in two main patterns: a spreading fibrous network, or a single thick tap root that also stores food.

• Roots: The part of a plant in the soil. Roots anchor the plant and take in what it needs from the ground.
• Stem: The part that holds a plant up and connects the roots to the leaves.
• Leaves: The flat green parts of a plant. Pine needles, blades of grass, lily pads, and cactus spines are all leaves.
• Modification: The same plant part built in a different shape or size.
• Fibrous roots: A spreading network of many fine roots, like a handful of strings.
• Tap root: One thick root driving straight down, reaching deeper water and storing food. A carrot is a tap root.

1. A cactus has spines instead of broad flat leaves, and a desert gets very little rain. Why might a small hard leaf suit a dry place better than a big soft one?
2. Grass in a lawn gets cut every week and keeps growing. If you cut the top off a young tree, it usually does not recover the same way. What might be different about where each one grows from?
3. Guess, before we study it: what do you think each of the three parts is for? Write your guesses down and keep them.

• One healthy starter plant or seedling in its pot. Newspaper, and a magnifier if you have one
• A trip to the kitchen and the yard, and a notebook