Upon brief examination, ferns would seem to differ little from most of the plants with which we are familiar. They grow in soil, they have stems and stalks, they produce green leaves; just a regular old plant, right?
But I’m going to ask you re-consider that assumption for a moment to ponder the following question: when have you ever seen a flower on the many varieties of fern that, as hikers, you’ve surely encountered throughout your journeys? I’ll give you a minute to search your memory…
The simple fact of the matter is that ferns don’t produce flowers, at all… a characteristic which distinguishes them from the dominant forms of plant life in the world today. The ordinary plants with which we are most familiar all develop flowers of one form or another. These flowers are basically the sex organs of the plant which are fertilized by pollen in order to produce seeds. Indeed, seeds are what we generally think of as the obvious vehicle by which plants reproduce.
But if ferns don’t produce flowers, and thus don’t produce seeds, how can they possibly persist? The answer to this paradox lies in a vehicle of reproduction which we have become accustomed to associate with an entirely different form of life: mushrooms. Mushrooms don’t produce seeds either, but they too don’t seem to have a problem persisting or spreading their species over large areas of their environment.
Ferns, like mushrooms, produce spores… incredibly tiny reproductive vessels that, unlike seeds, do not contain an embryo. Spores are released from ferns in incredibly large numbers and are generally released into the air in the hopes that they will travel elsewhere to establish new colonies in untapped terrain.
While it may seem strange, this method of reproduction has served ferns rather well over the course of prehistory. There was a time, roughly 300 million years ago, when ferns “ruled the world”, so to speak. They were the most dominant form of leafy vegetation in existence at that time, with some species growing as tall as 100 feet and producing stalks that could measure as much as 5 feet in circumference.
As climate change re-shaped the Earth’s environment, however, many ferns species began to die out and that’s when flowering plants had their opportunity to take center stage. Not only did they take center stage, but over millions of years, they practically stole the show.
Nonetheless, ferns could hardly be called “rare” these days, even if they lost their dominant role to flowering plants millions of years ago. And perhaps this is because their strategy of producing spores, rather than seeds, offers them a few unique opportunities that flowering plants are content to due without.
Seeds are typically much larger than fern spores, which are nearly invisible to the naked eye. The bulk of a seed is comprised of two things: an embryo and a generous supply of food that can be called upon to aid the growth of seedlings. Spores, on the other hand, contain little or no stored food whatsoever. For this very reason, spores can be incredibly light, able to travel enormous distances upon little more than a light, persistent breeze. When Mount Saint Helens erupted, destroying most of the surrounding plant life, a fern native to Japan was amongst the first to re-colonize the area!
On one hand, flowering plants can try their luck in a wide range of environments. Seeds have enough stored fuel to give seedlings a fighting chance even in less than perfect conditions. On the other hand, seeds don’t travel very easily by their lonesome. That’s the reason that all manner of clever means of distribution are employed… clingy burrs, shells resistant to digestive systems, helicopter-like pods that can fly on the wind, or airy seeds covered with tiny filaments that may float long distances before being deposited.
Spores produced by ferns don’t usually need to employ such complex means of distribution. Instead, the minute spores are produced by the millions and allowed to drift away with minimal help from animals or evolved aerodynamics. This simplicity comes with a price, however… spores lack the built-in food sources utilized by seeds. Because of this, truly ideal conditions are required for a spore to flourish, and the striking numbers in which spores are produced by ferns is a reflection of the crap shoot undertaken when sending these colonizers out into the world without supplies.
But spores can persist much longer in harsh or uninviting conditions than seeds, which have a comparatively limited range of viability. Fern spores can literally wait around for the right conditions to come to them, and so even though many spores ultimately strike out in the search for suitable habitat, others are rewarded for their patience.
While ferns may no longer be the “top dog” of the plant world, they have secured an enormously successful niche for themselves that is likely to see them persisting for millions and millions of years to come. Flowering plants, though incredibly efficient in their own right, cannot entirely out-compete the fern’s unique ability to distribute such mass quantities of small, hardy colonists.
The next time you happen upon some ferns along the trail, take a moment to appreciate the intriguing means by which these ancient organisms have persisted throughout the history of life on Earth. Modern ferns are living and reproducing in much the same way that their ancestors did a couple hundred million years ago… long before anything even remotely like a mammal, much less a human, could be found in the world.