About the Cover

Like all mosses, the peat moss shown here lacks a vascular system, so it can’t grow tall enough for the wind to carry its spores. But it elevates its spores a different way. As its spore capsules dry over time, they collapse. The rising gas pressure inside the capsule blows the lid off and thrusts the spores high enough to be transported by air currents. To learn more about ballistic spore and seed dispersal, turn to the Quick Study by Dwight Whitaker. (Image by Esa Ervasti/Alamy.)