A species
Bracken fern
Pteridium aquilinum
The fern that spreads widely without seeds
You and the bracken fern last shared an ancestor about 1.8 billion years ago (on 28 July, if life's history were one year).
You might expect such a big, successful plant to make seeds. Bracken fern never does. It is a land plant, a relative of mosses and seed plants, yet it has no flowers, fruit or seeds. Instead it sheds dust-like spores from narrow brown bands tucked just inside the curled edges of its leaves.
Taken as a group, bracken ferns are among the most widespread plants on Earth. They grow on all continents except Antarctica, in many temperate and subtropical places except hot and cold deserts. Look for their bright green coiled fiddleheads in spring. By summer each leaf has its own stalk, about as high as a kitchen bench, spreading into a flat triangle like an umbrella. In cold places, the leaves turn gold to rust-brown in autumn before they die back.
What you see is only half the story. The leaves share thick underground stems that can grow longer than a bus. After fire or clearing, these stems spread fast and form wide patches.
Poisonous all through
All parts are poisonous, fresh or dried in hay. It can harm horses and cattle, and milk from cows that eat it may be unsafe.
A tiny second plant
The big leafy fern is only one stage. Its spores grow into a separate plant so small you could easily miss it.
Once useful, now weedy
People once gathered it for animal bedding, tanning, soap and glass making and fertiliser. Now it is often a hard-to-remove weed.