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  Illinois Prairies   


A prairie is a type of grassland. The name comes from the French word for "meadow." You may have heard of the steppes in Asia, the pampas in South America or the veldt in Africa. These are all grasslands, too. Grasslands cover about one-fourth of the earth's surface and are the largest habitat in North America.

Prairies usually form on level or smoothly rolling landscapes. These areas have a dry or cold season that kills the plants so that they can burn. Most of the prairies in North America developed in places where the amount of rainfall each year is low. The Illinois prairies receive enough rain to support large trees. Frequent fires stop trees from overcrowding prairie plants.


Most of the land in the northern two-thirds of Illinois is flat. The land took this shape after glaciers moved through. These giant walls of ice formed and spread at a time when the climate in North America was much colder than it is now. The massive weight and grinding action of the glaciers pushed the soil and flattened it. Four major glaciers covered parts of Illinois during this period which ended about 12,000 years ago. One of the glaciers, the Illinoian, moved south to Carbondale in southern Illinois. This was as far south as any glacier in the United States reached at this period of glaciation.

The weather conditions in Illinois over thousands of years helped determine that prairies would exist in Illinois. The climate of the prairies is characterized by hot, dry summers and cold winters. When these conditions developed about 8,300 years ago, the tallgrass prairie became a major part of Illinois.

As the climate warmed and the glaciers began to melt, huge amounts of water flowed from them. These moving waters helped to form today's river valleys, especially of the large rivers in Illinois, like the Illinois and Mississippi. The waters also carried lots of sand and gravel. This load of rocky material was dropped to the river bottom when the river current slowed. Eventually the glaciers produced less water and the rivers became smaller. Some of the material carried by the rivers was now out of the water. Along the Illinois, Mississippi, Green and Kankakee Rivers, sand prairies were formed by this process.


Prairies are made of a mixture of grasses and forbs. Forbs are plants with broad leaves like wildflowers. Grasses have narrow leaves. Grasses are the dominant plant type in the prairie. To compete with grasses, some forbs send their roots further into the soil than the grasses so that they may reach water and nutrients that the grasses cannot. Short forbs bloom early in the spring before the grasses start growing, while taller forbs bloom later in the season.

Prairies are classified as wet, mesic or dry. Wet prairies have much water present in the soil. Plants like cordgrass, mountain mint and New England aster grow here. Mesic prairies have a medium amount of water during the year. Big bluestem, black-eyed Susan, compass plant, rattlesnake master and yellow coneflower live in mesic prairies. Dry prairies are inhabited by such plants as little bluestem, leadplant, purple prairie clover and rough blazing star.


In 1820, Illinois had 22 million acres of prairie and 14 million acres of forest. Prairies were mainly in the northern two-thirds of the state with forest in the southern one-third. All but nine current Illinois counties had large areas of prairie. In central Illinois, trees could only be found in scattered sites called "prairie groves." Illinois was the first state that settlers from the East travelled to that had such large areas of grasslands. These settlers are responsible for calling Illinois the "prairie state."

By 1900 most of the Illinois prairie was gone. The development of the self-cleaning steel plow and the richness of the soil meant that most of this land was converted to agricultural practices. By 1978 less than 2,300 acres of high quality prairie remained. Most of the undisturbed prairie sites in Illinois today may be found along railroad rights-of-way, in pioneer cemeteries or on sites unsuitable for farming.


Living on the prairie was not easy. The many biting insects found here made life miserable for everyone. The grasses grew so high that people could not see over them. People got lost because there were few landmarks to guide them. The weather, ranging from droughts to blizzards, was often unpleasant. Yet many settlers remained.

Some prairie sites were given unusual names by the people who settled there. "Froggy Prairie" in Adams County came about from a spelling bee. The frogs on the prairie were calling so loudly during the spelling bee that a teacher had to shout to be heard. A student said that the place was "froggy," and the name stuck.

"Macoupin Prairie" in Greene County comes from the Native American word "macoupin." This was the name they gave to an aquatic plant whose roots were used for food. Today we call the plant the American lotus.

"Crow Prairie" in Putnam County was named for the many crows in the region.


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