Spotlight on Sporophytes

It's a great day for a bog walk. During your stroll, you pause and crouch to admire a beautiful hummock covered in lush sphagnum moss. The feathery moss looks saturated and healthy. Hang on... something seems to be stuck to the tips of some of the moss leaves. You take a closer look. They're brown balls that resemble tiny berries. What are these strange growths?

Mosses do not reproduce with seeds, like flowering plants. Instead, they produce spores. A moss spore is a single cell that can grow into a new plant. It doesn't have the "bonus features" that come with seeds, like food for a sprouting embryo.

To produce spores, mosses send up a sporophyte. Some kinds of mosses have sporophytes that look like wispy antennas dangling little cocoons, or garden-gnome-style elongated caps on sticks. Sphagnum sporophytes are thick stalks topped with a ball-shaped spore case. Each sphagnum spore case contains 20,000 to 240,000 spores!

Can you spot the sporophytes? Photo by Emma Flickinger

To send their spores into the world, sphagnum sporophytes shoot them out like confetti from a cannon at 30 meters per second. The spore case propels the spores using compressed air. When the moss is wet, the spore cases are spherical, but they dry into a cylinder shape. As the spore case changes from a sphere to a cylinder, the air inside is compressed into a smaller space. Eventually, the increasing pressure blows the top off the cylinder and blasts the spores straight upward. The spores are carried by the wind to sprout elsewhere.