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!

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