The Evolution of Ferns
To truly appreciate ferns and their significance for the evolution of our Earth, we must first understand how they came to be and what role they played in Earth's early days.
Ferns Evolved over many millions of years to be successful and easy growing plants
Due to their longevity and their unremarkable nature, you might mistake ferns for primitive.
However, ferns are prime examples of finding a winning formula and sticking with it. An example is the interrupted fern, Claytosmunda claytoniana (syn. Osmunda claytoniana), which is found in gardens and wild spaces in eastern Asia and eastern North America.
There are fossils of this exact fern that date back 180 million years. All the way down to the fossilized cells, the modern interrupted fern appears to be virtually unchanged after all those eons. Tyrannosaurus rex would not have only been familiar with this fern, but it had also been flourishing for more than 100 million years before T. rex even appeared on the scene.
There have been several significant changes in the history of plant evolution. The ferns belong to a group of plants called seedless vascular plants, meaning they have one of the most important innovations in plant life (vascular tissue), but lack another important part -- flowers and seeds.
Claytosmunda claytoniana (syn. Osmundo clay-tonian.), the interrupted fern, has remained unchanged for 180 million years.
To understand how ferns evolved, we first have to look at how the simplest of plants came to be and how those plants went on to change and evolve.
FERNS AS A SIMPLE ORGANISMS
Some of the simpler organisms are the single-celled green algae, which generally make their living floating in water and photosynthesizing. Eventually, those single cells began to form larger, multicelled organisms often called seaweed. Algae were likely the first land inhabitants living in a wet film and they are believed to have given rise to the increasingly more complex earliest land plants, liverworts and mosses. These are the earlier, nonvascular plants, which means they lack a vascular system to move water from one part of the plant to another.
For algae living in the water, this is obviously not a problem, but for nonvascular plants on the land, such as mosses, the lack of a vascular system significantly restricts
the size of the plant. Mosses can soak up water like a sponge, but their lack of a system to pump water up from the ground means they can't support tall stems or wide leaves.
As a result, mosses remain low, ground-hugging cushions.
Tall vascular plants and the first ferns began to inhabit the Earth hundreds of millions of years ago.
Plant life started to rise off the ground when the first vascular plants arrived on the scene some 425 million years ago.
Vascular tissue, which consists of tiny tubes running up plant stems, sometime further strengthened with the organic compound lignin, freed plants from clinging to the ground.
Being tall is no great virtue on its own, but when a plant is fighting with other plants for valuable sunlight, height allows it to shade out the competition.
Nonvascular plants, which had been happily forming green carpets basking in the sun, suddenly had to adjust to living in the deep shade of their taller competitors, or extreme conditions in which their tall relatives couldn't survive. Mosses, liverworts, and their kin got pushed to the sidelines over the next several million years as vascular plants quickly dominated the surface of the Earth, towering 100 to 150 feet (30.5 to 46 m) in the air.
It is at this time that the first ferns made their appearance.
This explosion of lignin-reinforced vascular tubes enabled plants to reach soaring heights, creating the first forests.
These massive forests in turn created an important facet of our modern world: coal. The era of seedless forests was also a time of very active plate tectonics.
Continents were crashing into each other, pushing up mountain ranges and burying some of those new forests deep underground, transforming their trunks and foliage into the coal that fueled the Industrial Revolution.
The next big evolutionary change in plants left ferns behind. The first seed plants arrived on the scene some 350 million years ago.
Ferns and other seed-less plants such as mosses reproduce via spores.
Each tiny spore is fragile, requiring constant moisture to germinate and produce another generation of ferns.
Seeds, on the other hand, give a baby plant a start-up package. Inside each seed is an embryo and, almost always, a supply of food; when a seed germinates, it has time to develop an initial root to harvest water before it begins to photosynthesize.
This technique of giving baby plants a head start in life was wildly successful and allowed forests of conifers to dominate the landscape.
The Many Uses of Ferns
Ferns have been put to many uses by humans over our long history.
We've been eating ferns for a long time, and many cultures around the world eat a wide variety of fern species, mostly harvesting the new fronds before they've fully unfolded, at the so-called "fiddlehead" stage. Bracken ferns are of course eaten this way, but quite a few other species are as well.
In Taiwan and elsewhere in Asia, the fronds of the bird's nest fern (the genus Asplenium) are popular as a vegetable. These tropical ferns are popular as houseplants around the world, and their broad, leafy fronds are quite tasty as well. Unfortunately, there is mounting evidence that many ferns, not just bracken fern, are possibly carcinogenic if eaten regularly, despite being tasty. if you want to indulge in fiddleheads, it is best to do so in moderation.The stems of the Equisetum species, commonly called scouring rush or horsetail, contain silica and can be used to scour pots and pans.
They can also be used to file wood and to make reeds for clarinets. One type of aquatic fern, the genus Azolla, is an effective fertilizer. This tiny fern has a symbiotic relationship with a cyanobacterium that converts nitrogen in the atmosphere into a form that plants can use as fertilizer.
Because Azolla, when partnered with its bacterial friend, can produce its own fertilizer, this little fern can become a pest, doubling its mass every few days and quickly covering large water surfaces. But the vigor of Azolla has been put to good use in Asian rice farming. Rice needs a lot of nitrogen to produce maximum yields, so farmers inoculate rice paddies with Azolla, encouraging it to spread rapidly and release its nitrogen bounty to the rice as it decomposes.
Azolla is attracting new attention from researchers, in part because of this humble little fern's history. Around 50 million years ago, the world was a very different place, and much warmer thanks to high levels of greenhouse gases in the atmosphere. The Arctic Ocean was essentially a huge, warm lake—the perfect habitat for Azolla ferns.
We certainly love our ferns @verdantlyfe and you can check out our assortment of ferns by shopping our Fern & Allies Plant Collection.