Stepping into a fern-dominated forest is like stepping back a 100 million years into prehistory. You can almost imagine somewhere in the background a triceritops munching away, with one eye on the alert for t-rex. These plants are that old.

Ferns are among the oldest and most abundant plants on the planet, dating back more than 300 million years. There are nearly 11,000 species of them worldwide, living in just about every climate, every habitat except for the most extreme. There are more than 160 species in Florida, of which the Institute for Regional Conservation lists 124 as present in South Florida.

There are ferns that live in water, on land and in the air — epiphytes. Some grow like trees, some like vines. They can be extremely useful or extremely destructive. One, old world climbing fern, is among biggest environmental rogues in the wilds of South Florida. Another, bracken fern, has been both pest and providence to us humans. And they appeal to our sense of aesthetics, occupying our gardens, our offices and our homes.

So what makes a fern a fern? First, they are vascular plants, meaning they have tissue that transports water and nutrients to their various parts the way animals have blood vessels (and the way most plants do). Secondly, they do not flowers but reproduce by spores that are produced by things called sporangia. Which brings up the language used to describe ferns. Some basics: leaves are called fronds. They can be simple — undivided like strap ferns — or compound — divided, like royal fern. The divisions, or leaflets, are called pinna. Pinna can be further divided — called bipinnate and the divisions called pinnules. If the pinnules can be dvided again, the fern is tri-pinnate. A newly emerging frond is called a fiddlehead and the central stem is called a rachis.