Archive - July 2021

Short forbs bloom early in the spring before the grasses start growing, while taller forbs bloom later in the season.

How did the Illinois Prairies Form?
Most of the land in the northern two-thirds of Illinois is flat. The land was shaped by glaciers that 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 weight and grinding action of the glaciers pushed the soil and flattened it. Four major glaciers covered parts of Illinois during this period that ended about 12,000 years ago. Prairies usually form on flat land with a climate that is hot and dry in summer and cold in winter. When these conditions developed about 8,300 years ago, the tallgrass prairie became a major part of Illinois.

What Types of Prairies grow in Illinois?
Prairies are classified as wet, mesic or dry. Wet prairies have much water present in the soil. Plants like cord grass (Spartina pectinata), common mountain mint (Pycnanthemum virginianum) and New England aster (Symphyotrichum novae-angliae) grow here. Mesic prairies have a medium amount of water during the year. Big bluestem (Andropogon gerardii), black-eyed Susan (Rudbeckia hirta), compass-plant (Silphium laciniatum), rattlesnake master (Eryngium yuccifolium) and yellow coneflower (Ratibida pinnata) live in mesic prairies. Dry prairies are inhabited by such plants as little bluestem (Schizachyrium scoparium), leadplant (Amorpha canescens), purple prairie clover (Dalea purpurea) and rough blazing-star (Liatris aspera).

Where are the Prairies in Illinois?
In 1820, Illinois had 22 million acres of prairie land. 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 land. By 1900 most of Illinois’ prairies were gone. The development of the self-cleaning steel plow and the richness of the soil led to the conversion of most of this land to farming 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 railroads, in pioneer cemeteries or on land unsuitable for farming.

How is Fire Important to the Prairie?
Fires occurred often on the prairies. Because the ground was flat and unbroken by roads or other objects, fires moved quickly and covered huge areas. Fire is good for the prairie ecosystem. Fire removes the dead stems and leaves of prairie plants above ground without killing the roots. These plants can grow again after a fire from either their roots or their seeds. Fire helps to stop the growth of shrubs and trees in the prairie by killing the living parts that are above the soil. These plants do not grow back from their roots as easily as grasses. It is believed that frequent fire was the reason that Illinois was covered with mostly prairie instead of forest when the pioneers arrived.

What Types of Plants grow in a Prairie?
Prairie soil is very rich in nutrients that plants need to grow. Bacteria and fungi break down dead organisms, returning nutrients to the soil. Grasses grow so close together on the prairie that the soil is packed with their roots. This prairie “sod” helps to conserve both soil and water. It acts like a sponge when rain falls. Some settlers even used sod to build their house.

Big bluestem is the state prairie grass. This plant may grow to a height of 12 feet!

The compass-plant has leaves in a north-south arrangement to allow the most sunlight to be absorbed. The plant may grow 10 feet tall.

Black-eyed Susan plants are covered with hairlike structures, making them feel rough when touched.

Downy gentian’s (Gentiana puberulenta) flowers are blue-purple. When downy gentian is found today in a natural prairie, it means that the area is undisturbed.

Rattlesnake master was used to make a drink as an antidote to rattlesnake venom. Pioneers believed that if this plant was present then the eastern massasauga (Sistrurus catenatus), a prairie rattlesnake, must be near.

What are Some Animals of the Prairie?
Prairie animals must withstand changing weather, danger from predators, dry conditions and other hazards, like fire. To meet these challenges, many prairie animals can burrow into the soil, run fast, fly or blend into their surroundings. Prairie birds must often nest on the ground since there are few trees available.

• The northern harrier (Circus hudsonius) is an endangered Illinois raptor. This hawk has slim, long wings and a long tail. Its white rump patch makes it easy to identify.
• The monarch butterfly (Danaus plexippus) lives on the prairie. The female lays her eggs on milkweeds, which the larvae use for food when they hatch. The monarch is a migratory butterfly.
• The sedge wren (Cistothorus platensis) builds its nest in the prairie grasses. This tiny bird eats insects and spiders that it finds in the grasses or on the ground.
• The thirteen-lined ground squirrel (Spermophilus tridecemlineatus) eats stems, leaves, seeds and roots of prairie plants and insects. This small rodent lives in burrows it digs in the rich soil. The burrows may be as deep as 1 1/2 feet.
• The American toad (Anaxyrus americanus) is a prairie amphibian. It is active at dusk or at night, seeking insects and worms to eat. Females tend to be larger than males.

Are There Endangered and Threatened Prairie Species?
Because much of the prairie has been destroyed, many of the organisms that depend upon it for their habitat (food, water, shelter, space) have been forced to move to new habitats or have become very scarce themselves. Did you know that bison and elk once lived in Illinois? They were the largest mammals of the Illinois prairie. Many were killed by pioneers and used for food and hides. Others lost their habitat to farming and settlement. With the loss of habitat, these animals vanished from Illinois, although they still lived in other states. They were extirpated from the state. Today the list of threatened or endangered prairie species in Illinois includes plants, butterflies, frogs, snakes, birds and mammals. Without the large continuous grasslands, these organisms will always find survival to be difficult. Prairie restoration efforts help to keep these organisms alive.

What Else Should I know about Prairies?
Illinois was the first state that settlers from the eastern part of the country travelled to that had such large areas of grasslands. These settlers are responsible for calling Illinois the “prairie state.”

The third full week in September is celebrated as “Prairie Week” in Illinois. This annual event occurs thanks to a law passed by the state legislature. The purpose of the observance is to develop in people an appreciation of prairies.

​Click here for educational resources about Illinois prairies!