What Are Fern Adaptations?

More than 10,000 different species of ferns exist throughout the world today, and these holdovers from hundreds of millions of years ago have made a number of adaptations to ensure their continued survival. Their structures are very different from other types of plants, placing them in a category that is all their own.

If the fronds of the fern are similar in structure and function to the leaves of other types of plants, the rhizomes play the role of the stem or the trunk. Fronds sprout from the rhizomes, which are thick, woody structures that are completely or partially buried underground. The woody rhizomes not only provide support for the fern's fronds, but they also contain the plant tissues that are responsible for moving nutrients throughout the plant as well as storing energy. These types of ferns have adapted their underground rhizomes with survival in mind; they are at least partially protected from severe weather and even forest fires.

Since ferns don't have flowers to bear the seed-producing structure, these plants have had to find other ways to reproduce. Sporangiia are the structures on ferns that produce, hold and disseminate the seeds, called spores. The design and position of these structures vary among the different species of ferns, but often they can be found on one side of the fronds arranged in symmetrical patterns.

The sporangiia of some ferns are protected from the elements by thin coverings, while others depend on the shape of the fronds to shield the spores until they are fully formed. While ferns can produce and shed billions of spores, only a handful will take root in the soil to grow into new plants.

Ferns have adapted a complex life cycle that allow them to function without having adult plants produce both male and female parts and to get a head start on their competition. Many spores never get the chance to develop; spores that do begin to take root do not directly grow into a new fern.

Instead, these spores produce the male and female parts of the fern, which develop only after the spore has had the chance to grow the beginnings of rhizomes and the fern's heart material. Once this root material has been started, male and female structures are created by the spore's process of cell division, and the female egg is fertilized. Fronds only begin to grow from this fertilized egg, and they already have a firm start established with the rhizomes and stems that have already begun to grow.

Many ferns grow in areas of intense competition, from the forest floor to the canopies of trees. Some varieties have developed a symbiotic relationship with a type of fungus known as the mychorrhizae. The fungus grows on the rhizome of the plant and clings to its underground root structure, where it absorbs some of the sugars that the fern takes from the soil.

At the same time, the life processes of the fungi increase the rate at which the fern can absorb nutrients at the same time it filters out some of the contaminants that would otherwise harm the fern. The establishment of the fungi on the root system also makes the fern better able to withstand extreme soil conditions such as drought.