Throughout literary history, bogs have been portrayed as the gloomy retreats of society's outcasts. It was a Danish bog from which the monster Grendel emerged to attack Beowulf's castle; bogs, or heaths, of medieval Britain sheltered the marauding pagans who became known as heathens; and much later, the fiery Hound of the Baskervilles came lunging across the British moors, hungering for victims lost in the treacherous bogs.
While New England's bogs seem tame by comparison, they harbor a number of unusual life forms. A bog is a stagnant pool which lacks the circulation necessary to supply nutrients like phosphorus, nitrogen and lime, or to carry away dead materials. The only source of fresh water is rain, which is almost totally lacking in nutrients. The accumulation of dead plants that sink to the bottom of the bog can make the water as acidic as orange juice.
Residence in a bog, therefore, is limited to those hardy plants that can endure the adverse combination of high acidity, high moisture and low nutrients. Sphagnum moss, commonly called peat moss, is an acid-loving plant that thrives in the bog. Its feathery stems and leaves can absorb as much as one hundred times their own weight in water. Native Americans made use of these water-absorptive qualities by using dry sphagnum for diapers. During World War I, sphagnum was used as surgical dressings in battlefield hospitals.
Because of the acidic, sterile environment of the bog, only about two dozen families of plants are apt to be found there. Many of them are left over from the Ice Age, when Arctic plants accompanied the glacier south, then remained behind after the ice disappeared. Leatherleaf, bog rosemary and sheep laurel have thick, waxy leaves to retain what little moisture is available from the bog. Although bogs are moist, the high acidity of bog water interferes with the plants' ability to absorb it. Labrador tea has a leathery upper leaf and soft orange fuzz underneath to prevent water loss. More familiar members of the plant family, including cranberries and high-bush blueberries, also populate the bog.
Small orchids and carnivorous plants offer some of the more interesting examples of bog life. Carnivorous plants obtain the nitrogen and phosphorus they need by eating insects. The pitcher plant, the largest insectivorous plant in the bog, is a striking example of form following function. Its prominent feature is a six-inch leaf curled in the shape of a pitcher. The hollow cup is partly filled with water and digestive enzymes. The "pouring spout" of the pitcher is a landing platform for insects attracted by its red venation and nectar glands on the outside of the plant. As the insect crawls closer to the edge of the pitcher, it loses its footing on the slippery, downward-sloping hairs and plunges into the liquid. Enzymes or bacteria begin working almost immediately, while the stiff hairs prevent the escape of the unlucky insect.
The sundew, another insectivorous plant, was named for the way its shiny tentacles glisten in the sun. Each tiny leaf is covered with up to two hundred viscid tentacles that capture small insects. When a midge or mosquito lands on one of the red leaves, its feet become ensnared in the globules of sticky liquid Within two minutes, the tentacles, stimulated by the struggles of the insect, begin to curl around the victim. The bending of each tentacle is caused by differential growth-one side of the tentacle grows faster than the other.
Pitcher plants and sundews prey on insects, but there are other plants in the bog that are hazardous to larger animals, especially humans. Occasionally, a bog explorer plunges through a thin spot in the sphagnum mat and emerges the color of peat. The greatest danger, apart from catching cold, lies in grabbing for the wrong tree to break the fall. Larches, swamp maple and black spruce are all accept able, but beware a tall, tree-like shrub with compound leaves and white berries. It is poison sumac, which leaves a rash far more durable and annoying than poison ivy or poison oak. Fortunately, poison sumac only grows in bogs; it is not the familiar sumac that thrives in vacant lots and along the edges of fields.
Few animals live in the bog, although many pass through it in search of food or shelter. Permanent residents include insect-eating birds, bog lemmings, garter snakes, frogs and turtles who feed on large insects. Almost no fish thrive in the acidic water of the bog.
Although the surface of the bog offers little variety of animal or plant life, its layers of peat represent an uninterrupted record of the myriad species of plants that have grown there since the Ice Age. Plant pollen, the fine yellowish spores that fertilize flowers, are very resistant to decay, especially within the airless bog. For thousands of years, pollen grains have blown into the bog and been buried there, creating a vertical history of the kinds of plants that once existed in the surrounding forest. By examining core samples of bog sediments, botanists can reconstruct the plant succession and climactic changes that have occurred in the area around the bog. Thus a Maine bog is not only a relic of the Ice Age and a refuge for migrant Arctic plants, it is a botanical clock as well.
There are many mysteries yet to be unearthed in the bog, but they have nothing to do with the witches, monsters and bogeymen of classical folklore. The real mysteries concern the habits and adaptations of the curious plants that survive there. Maine bogs are included in legislation that restricts the alteration of secrets intact for future bog explorers to uncover.
For further reading: Glob, P.V. The Bog People. Cornell University Press. New York, l969