One Fen, Two Fen, Red Fen, Blue Fen

“Late afternoon in the bog” by Liam Moloney. License CC by 2.0

Say! What a lot of fens there are. Parallels have been drawn between race, ethnicity, and Dr. Seuss’ poem about fish in the past. But to me, wetlands emulate the essence of the poem. Of wetlands there are many types, including bogs, fens, marshes and swamps. A list of wetland types by WWF gets into even more detail. Some I was even unfamiliar with: pocosins, billabongs, and mires to name a few. Let’s delve into the distinctions and why they matter.

nature moss hills bog
Photo by Jaymantri on


Rainfall maintains the water level in most bogs. However, they were originally carved out by glaciers and lakes. Bogs are known for layers of thick, spongy sphagnum moss that cover the ground and absorb impact as you walk. Pocosins are a specific kind of bog with an acidic pH, deep soil, and abundant evergreens.


According to the USDA, fens are wetlands that are groundwater-fed. Fens can be further classified by shape and nutrients. Sedges, grasses, flowers and shrubs are most likely to cover the ground in this situation.

brown frog surrounded by green floating pants on water
Photo by Richard Fletcher on


Marshes are areas of still water that foster a great deal of aquatic plants such as water lilies, duckweed (which you can see floating in the water from the image above), cattails, bulrush and more which are listed on the Wisconsin Wetlands Association website.


A billabong is created when the path of a river is altered, leaving behind a solitary pond.

Swamps and Mires

Swamp versus mire characteristics are unclear, but from what I have gathered, swamps imply still water and the presence of trees. The term “mire” includes any waterlogged area with some sort of vegetation present. Thus, all wetlands qualify as mires.

landmark island
Photo by Tobias Bjørkli on

Why It Matters

Let’s say the government crafts a law to protect wetlands. The law says that no wetlands can be drained for development. Using a term that is too broad might allow land owners to slip through the cracks and use the land for development anyway. By clearly outlining what a wetland is, protecting the environment becomes a little bit simpler.

There are also implications for research. Sometimes wetland characteristics help us to draw conclusions about how the wetland works as a system. By studying similar kinds of wetlands and categorizing them, information can be shared about how fens or bogs work, for example, and can be extrapolated to other places of the world that have similar environments. Scientists can also use observations to produce estimates of how many wetlands there are in a certain country. They can then quantify other more complicated terms like how much CO2 is sequestered in a year or overall CH4 emissions from wetlands.

Ever more terms are used to describe wetlands aside from what I wrote here. Lagoons, estuaries, reservoirs, and the like all help us to put into words what we see in an ecosystem. If there are ones you’ve heard of, don’t hesitate to let me know in the comments!

14 responses to “One Fen, Two Fen, Red Fen, Blue Fen”

  1. These were very interesting facts! I was particularly interested in the Marsh, as I like to learn about plant life. This is silly on my part, but to a certain degree I would use swamps, marshes and such interchangeably to describe watery areas. I now know there are very distinctive differences. Thank you for teaching me more about the world around me!

    Liked by 1 person

    1. Thanks for reading! Yeah, I think these terms are interchangeable when it comes to using words as an art form- like in poetry or something. But when you translate them into science they mean something entirely new

      Liked by 1 person

  2. This was a super helpful post for me. I’ve never completely understood the difference between a marsh and a swamp, except that I knew swamps tended to have more trees; I’ve also never heard of fens or mires before.

    Liked by 1 person

    1. Hey Josh
      Thanks for stopping by, hopefully these terms help you in ecological trivia down the road…a mire is not to be confused with a shire, which is an area separate from the rest of Middle-earth!

      Liked by 1 person

      1. Lol, a Shire is my favorite geographical classification of all!

        Liked by 1 person

  3. Thank you for this interesting article. I was not aware of the various definitions for wetlands.

    Liked by 1 person

  4. Wonderful post. Conserving these water bodies are one of India’s biggest issues. We don’t do enough justice towards conserving them at all, more so now when a lot of cities and towns are running out of water and natural areas!

    Liked by 1 person

    1. In Wisconsin, wet areas can have a lot of ticks and mosquitos so I see why people want to drain them or get rid of them altogether.
      But when we learn how fens and bogs help our ecosystem, we value them more. Thanks for reading, Tamanna!

      Liked by 1 person

      1. That is so true! I hope we are able to create more awareness about them, before we have drained them or converted them for other purposes!

        Liked by 1 person

  5. I’ve always wondered what a billabong was. Now I know!

    Liked by 2 people

  6. Hello Jess! I loved going though your blog. And learned a lot today as well. You’re right, its imperative to know the classifications to truly understand the gov policies.

    Liked by 1 person

    1. Thanks for reading, Mithai 🙂


  7. This is a very informative post, I learned a lot. Thank you.

    Liked by 1 person

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