In the fall and winter, the head can be broken apart or shaken apart to reveal thousands of tiny, wind-dispersed seeds. Instruct the students to smell the soil that the cattails are rooted in. This rotten egg odor is due to the sulfur-containing compounds produced by the anaerobic bacteria that live in the anoxic soil. Discuss the importance of this adaptation to anoxic soil, how oxygen is transported within the lacunae to the roots, and why oxygen is required in the roots. Cut the cattail leaf parallel to the long axis to examine the diaphragm-like structures in the lacunae.
Bulrushes Cut a bulrush leaf perpendicular to it s long axis.
To demonstrate the buoyancy of the bulrush stems, throw one into the water. It will remain afloat because of the gas-filled lacunae. Mention that Native Americans used these buoyant stems to make rafts. Willows Discuss how the willow is still susceptible to watersaturated soil even though it is not found near the ponds. Try to find some air roots on the trunk of the tree and describe how the willow has adapted to the anoxic soil.