From the tallest sequoia to the smallest violet, plants pull water up from the ground through their roots and into the long, thin tubes called xylem. To illustrate this amazing feat, pour fresh water to the halfway point in three glasses and add three or four drops of red food coloring to the first glass, an equal amount of blue food coloring to the second glass and leave the third glass alone. Place a white carnation in each glass, being careful to first make a fresh cut on the end of the stem – dried out stems won’t take up water. Allow them to sit overnight and record your observations the next day.
Sometimes plants take up too much water -- like after a heavy rain – and they shed the excess through their leaves. In transpiration, water is evaporated into the atmosphere, typically through leaf pores called stomata. Do a quick experiment demonstrating this process with any living plant. Cover a leaf with a sandwich bag and secure it to the stem with tape or a twist-tie. Place the plant in a sunny location for two to three hours, making and recording observations every 30 minutes.
Unlike people, plants can make their own food by using sunlight to turn water and carbon dioxide into sugar. But to do this, they need the chlorophyll present in their leaves to absorb sunlight. To determine what happens to a plant deprived of essential sunlight, sandwich each of five leaves on a broad-leaved plant in two pieces of black construction paper. Loosely cover five additional leaves with sandwich bags. For five days in a row, briefly remove both the construction paper and the plastic bags from the leaves. Record your observations and discuss the changes.
Flowers use their spectacular colors, shapes and sweet nectar to attract pollinators. Several flowers like irises, tulips, lilies, gladiolus and the amaryllis have large parts that make them ideal for a dissection project. Use fine-bladed knives to locate the female portion of the flower, called the pistil. Examine it for the tube-like style, ovary and the sticky stigma found on top; it is often covered with pollen. The male stamen is made up of pollen-producing anthers supported by thread-like filaments. “Perfect” flowers like irises contain both the male and female parts.