by Roy Lukes

Bogs Are Fragile, Fascinating Places


Quaking bog

A plant community, soggy yet exhilarating, almost as though a person were in a different world, continues to be one of the least visited habitats in this state. Very few members of the small number of groups I have taken into a bog in the past had ever experienced that incredible environment before.

Uncertain footing soon became the byword of each of those memorable outings. A loud gasp, sometimes accompanied by a chuckle, most often meant that someone’s foot had found a concealed hole. As fast as the blink of an eye, the unfortunate one found him or her knee-deep, or even thigh-deep, in black muck.

Bogs, common in northern glaciated regions of the world such as ours, are fragile places having more or less a continuous carpet of sphagnum moss. Little to no drainage occurs there. A visit to a true bog will reveal an enclosed water area whose edges are being invaded by a mat of floating vegetation.

This spongy, water-soaked mat of plants is gradually thickening from both top and bottom. Slowly the peat accumulates consisting largely, or entirely, of organic material. Layers as thick as 50 feet have been built up over the years as slowly as from 100 to 800 years per foot.

What a surprise I received on my first teacher-led visit to a bog around 42 years ago. Eager to examine a plant near the edge of the mat, I suddenly and shockingly broke through up to my waist in water. Luckily others were near to lend a helping hand. An important lesson many of us learned was that the quaking vegetation will support a person’s weight (or nearly so!) if you walk as though tiptoeing on eggs so as not to break any.

Due to the lowness of bogs, the coldest air from the surrounding terrain is constantly settling there. This, coupled with constant wetness, leads to highly acid conditions of the soil as well as the water in nearly all bogs. Tests as low as 3.5 and 4 on the pH scale, approaching the acidity of vinegar, are quite common. These cold and wet factors limit plant growth and decomposition, thereby increasing the acidity. Bear in mind, however, that there are a small number of alkaline bogs in the state which in turn feature entirely different plant communities.

The temperature variation in a bog is unusually great. Push your arm down into the sphagnum moss as far as you can and chances are good that you will discover ice crystals there in June. Leatherleaf, a typical bog shrub, will sometimes be in full bloom while its roots are surrounded by frozen soil. Mid-summer surface temperatures may reach 95 degrees F. while, at the same time, plant roots will be experiencing a definite deficiency of water at temperatures of around 50 degrees F.

Many of the shrubs of the bog are evergreen thereby allowing for the maximum number of days for the manufacture of food. Included in this group are Labrador tea, bog Rosemary, leatherleaf and bog laurel. A few deciduous shrubs grow here too such as blueberries and sweet gale. One of the very tiny trees, resembling a shrub, is the dwarf or bog birch.

Sedges, including cotton sedge (called cotton grass) and saw grass, are a common sight. For a long time I was baffled over calling one of the typical bog sedges "saw grass" when it really wasn’t a grass. A chemistry professor from UW-Janesville, interested in plants, provided me with a temporary answer by asking me, "Wouldn’t it be unfortunate to change the name of saw grass to "saw sedge?" And in July you may want to call it "summer saw sedge!"

Two of the most fascinating groups of bog plants are orchids and carnivorous plants. Orchids of Wisconsin bogs include the heartleaf twayblade, small round-leaved orchid, rose pogonia, grass pink, swamp candles, pink moccasin lady’s-slipper and arethusa.

The study and intricacies of carnivorous plants have attracted botanists to the bogs for centuries. Northern pitcher plant, both the round and the linear-leaved sundews and three species of bladderworts will reward the ‘bog trotter’ in this region.

Round-leaved sundews, small to the point of going unnoticed by many people, abound by the thousands in some bogs. Their leaves contain tiny spines tipped with a glue-like substance along their margins and on their inner surfaces. Unsuspecting insects, trapped like flies on flypaper, set up a response within the leaf whereby it slowly curls around and suffocates them. The spines then release a proteolytic enzyme, very similar to peptic juices found in the human stomach, into this little trap. Nitrogen, nearly lacking in the soil of the bog, is now assimilated from the insects’ bodies.

Bogs are truly fascinating. Henry David Thoreau summed them up perfectly when he said; "Surely one may as profitably be soaked in the juices of the swamp (or bog)…as pick his way dry-shod over sand. Cold and damp – are they not as rich experiences as warmth and dryness?"


This column appeared in the Door County Advocate on 07/09/1999.
© Copyright 1999 Roy Lukes. All rights reserved.