A species
Common haircap moss
Polytrichum commune
A moss with no true roots that holds water like a sponge.
You and the common haircap moss last shared an ancestor about 1.8 billion years ago (on 28 July, if life's history were one year).
No true roots, no flowers, no seeds, yet this little plant holds water like a sponge. Common haircap moss is a land plant, so it is a cousin of the bracken fern and the seed plants beside it on the tree. Instead of true roots it sips water up from its base through its stem, and tiny ridges on its leaves trap damp air to slow drying.
It grows in dense, dark green tufts. Its stiff stems are usually about as tall as a finger, though a few grow much taller. Narrow leaves spiral around each stem and look like a star from above. Male plants make yellow to red cups at their tips. After rain splash carries male cells to the female plants, a slender stalk grows on the females. It is topped with a tiny brown box.
Each young box wears a fluffy pale hood that looks like a tiny hairy cap and soon falls off. Then the box opens and lets dust-like specks drift away in the wind to start new tufts. You can find it in bogs, wet woods and along stream edges where the ground stays damp.
A world traveller
It lives across mild and cool parts of the Northern Hemisphere, and also in Mexico, New Zealand, other Pacific islands and Australia.
Moss brooms
In Europe, people once made tiny brooms from this moss and used it to fill beds.
A clue to sour soil
It almost always lives on sour soil, so where it grows the soil is likely sour. In some places it also helps show high mercury.