How Do Ferns Reproduce?

by | Botany

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Ferns have captured the imagination of many scientists’, with many aspects of these unique plants becoming a dissertation research subject. Some people have even dedicated their lives to studying the subject, always finding more questions than answers.

So, without diving too deeply into the subject, how do ferns reproduce? In this guide from HerbSpeak, we’ll discuss the answers to that, and much more about the fern’s unique life and reproductive cycle – all in fun, bite-sized pieces.

Ferns Are Some of the Most Ancient Plants

When we look at ferns, it can be difficult to understand the timescale on which the plants have thrived. One of the earliest forms of land plants, ferns are among the first successful plants to have evolved a vascular system. (1)

“Partly because of their considerable age, ferns contain a high amount of diversity, with some groups that look nothing like the more common representatives we usually associate with ferns.”

American Fern Society

This was a great advantage in a world that did not yet know widespread terrestrial plants. Up until that point, mosses, algae, and other non-vascular plants relied on staying close to sources of moisture to reproduce and thrive.

With ferns, however, it was a revolutionary new strategy in progress. Ferns would soon come to dominate much of the landmass on the planet, becoming widespread and diverse, until new land plants began to move in and evolve separately. 

How Do Ferns Reproduce? A Life Cycle

As soon as a spore absorbs moisture, the cells begin dividing and growing, developing into the gametophyte. This creates a moss-like appearance on the surface where the spores landed and contain both female and male reproductive parts required to create a new plant. 

When the conditions are right, these gametophytes release sperm, contained in what is known as the antheridium. These sperm use the surrounding moisture to swim, searching for eggs. These eggs are produced by what is known as the fern’s archegonium, which is located on the gametophyte.

Once the eggs are fertilized, it is free to begin growing as a young fern plant, which then produces a structure known as an immature sporophyte. This sporophyte must mature before it can bear new spores, but this is what we commonly see above ground as the fern’s fronds.

These sporophyte’s (AKA fronds’) individual leaflets are called megaphylls, to add another layer of confusing terminology to the mix. This may be relevant if you are learning botanical identification, but otherwise can be ignored safely.

This sporophyte develops a structure – sometimes small capsules, or an entirely other modified frond – known as the sporangia. This sporangium is what contains the individual spores.

Overall, the video above from creator Professor Dave Explains covers this cycle incredibly well in a little under 5-minutes. If you’re more visually or aurally inclined to learning, I would recommend giving this a watch before continuing.

Are Fern Spores Haploid or Diploid?

Fern spores in particular are haploid, however, this is not the complete answer as ferns as a whole organism live two separate generations in their life cycle. One part haploid, the other, diploid. (2)

When the fern spores are first produced, they are formed as a part of the diploid sporophyte generation. The sporophyte’s job is to produce spores that will result in another generation, but this is just the first stage of the plant’s reproductive cycle.

In other words, the spores are held inside the diploid generation, but themselves are haploid. The fern then goes on to the second reproductive phase to become a haploid generation, where it will release these spores to continue the cycle.

“Ferns are unique in that they have two independently existing generations, the haploid gametophyte and the diploid sporophyte.”

Appl Plain Sci

Overall, the fern’s dormant reproductive cycle is little studied, and there is plenty of research opportunity here for aspiring botanists looking to make their mark on this realm of study.

Are Ferns Male or Female?

In most cases, ferns are either male or female. Most ferns are capable of self-fertilization if they need to be, but this leads to a problem: a lack of genetic diversity.

Instead, ferns have developed a unique way of handling this situation that doesn’t leave its gender up to random chance.

The surrounding established ferns communicate with the younger generations, helping determine whether the plant should be male or female based on how weighted the balance is between the two sexes. (3) In a strategy to reproduce faster, this ensures that there are always eggs and sperm around in a community, mixing genetics around as much as possible for a stronger population.

If there is only a single fern, however, the gametophyte produces its own insurance policy: self-fertilization.

Why Do Ferns Reproduce Without Seeds?

Plant reproduction via seeds is actually a recent evolutionary development. Contrary to popular belief, it is not the only method that plants use to reproduce.

Ferns were alive and thriving far before the flowering plants evolved. In most cases, ferns don’t have a reason to develop a different reproductive strategy because their mixture of spores and vegetative reproduction suit their purposes just fine.

Can a Fern Reproduce Without Water?

After everything we’ve learned, can a fern reproduce without water? No. As vascular plants, ferns require water to function, and that includes during reproduction.

That said, a fern does not need to reproduce in aquatic conditions. While ferns are sensitive to the level of moisture, some are hardier than others. Too dry, and you’ll start losing fern diversity.

Do Ferns Spread Quickly? 

You’ll find that this answer isn’t so easy to answer, as it’s all circumstantial. In short, yes, most ferns do spread quickly in the environment because of how well spores spread as a reproductive strategy in the environment.

The same phenomenon happens with fungus; if the spores can be released, they float along in the air until they collect enough moisture to fall to the earth again, where they then use that moisture to begin growing. If the fern’s spores are not in conditions where they thrive, however, it will inhibit their growth.

In the deciduous forests of the northeastern United States, you’ll often find clearings of ferns, which prompts a lot of people to ask about how quickly ferns spread. These monocultures typically establish themselves after land clearing activities, and form a layer of fast-growing, fast-spreading underbrush that shade a lot of other diverse growth out.

While this isn’t an issue in some areas where other plant species have a foothold to compete, it can become a problem in the micro-region if ferns continue to grow in dense swaths.

It’s worth noting that ferns’ notorious ability to spread quickly doesn’t just come from spores, but primarily their vegetative reproduction. This has caused some ferns to gain an invasive reputation.

Why Are Ferns so Hard to Keep Alive?

Whether you’re managing land or keeping a houseplant, you’ll probably have some difficulty keeping ferns alive. For some of the most ancient forms of plants on the planet, ferns are notoriously finicky.

In most cases, people have difficulty keeping ferns alive because they are looking to keep ferns in a habitat they are not native to, or are not naturalized in. Whether this is a different habitat type, or solitary growth in a container, ferns need to be treated as if they were still in the wild. This means keeping the conditions exactly as the ferns would expect it.

Taking a look at the native habitat of your specific fern species can help. Most ferns like moist and fertile soil in a high shade, high humidity region, but they shouldn’t be overshaded or stay soggy. It’s a delicate balance, but also why many ferns tend to do better in native plant communities than they do by themselves.

When you help establish plants with the complex ecosystem interactions they are used to, you’ll have less work to do in the long-term.

References
References
  1. American Fern Society, About Ferns, https://www.amerfernsoc.org/about-ferns
  2. Quinlan A, Lee PH, Tang TY, Huang YM, Chiou WL, Kuo LY. Providing the missing links in fern life history: Insights from a phenological survey of the gametophyte stage. Appl Plant Sci. 2022 Apr 13;10(2):e11473. doi: 10.1002/aps3.11473. PMID: 35495188; PMCID: PMC9039788.
  3. Tanaka, K., Sex Determination Driven by Community Cooperation, DOI: 10.1126/scisignal.aaa1063

 

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About Destynnie K. Berard
I am a lifelong naturalist who believes a good sense of humor is essential to staying happy. ★ After traveling for years, I settled in New England, falling in love with the diverse landscape the Northeast has to offer, and began pursuing conservation in earnest. ★ My career background is in enterprise marketing and communications, which provides me with a unique perspective of ecological relationships.

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