THE PRAIRIES OF IOWA and the states immediately adjacent to Iowa’s borders are within the tallgrass prairie. The tallgrass prairie is on the eastern edge of the prairie formation or biome. This great belt of grassland stretches from the prairie provinces of Canada south to central Texas and west to the foothills of the Rocky Mountains.
Tallgrass prairie is found all along the eastern side of the prairie formation. The best large expanses still intact are found in the Kansas Flint Hills and south into eastern Oklahoma. The Sand Hills of central Nebraska also have large expanses of mixed prairie-tall, mid, and short grasses mixed depending upon moisture availability and exposure. Prior to European settlement, tallgrass prairie was concentrated in the “prairie peninsula” first described by Transeau in 1935.
The prairie peninsula extends from eastern Nebraska, southwestern Minnesota, and northwestern Missouri across Iowa and noses into the eastern forests of maple and oak across Illinois and southern Wisconsin, into Indiana, and even a bit into Ohio and Michigan. Iowa is the only state completely within the tallgrass prairie formation.
To the west of Iowa, across Kansas, Nebraska, and the Dakotas, the height of the vegetation becomes progressively shorter and is known as the midgrass prairie. Shortgrass prairies are found on the high plains and stretch across Montana, Wyoming, and Colorado toward the mountains.
The tallgrass prairie is very productive because of adequate summer rainfall and warm summer temperatures, although occasional severe drought occurs during the growing season. Grasses, sometimes with seed stalks over 6 feet tall, are common in late summer and fall. Sunflowers and compass plant nearly equal them in height. Hundreds of other species join them to produce a vegetation rich in diversity of color and form.
What should you expect to find when you visit a tallgrass prairie? Be ready for a large number of species at your feet. Be prepared for a tangle of grasses and forbs (flowers or non-grassy herbaceous plants) all around you. Expect to see something that resembles an unkempt hayland with little uniformity, except there are virtually no trees and hardly any shrubs. Get ready for many species to be in bloom anytime during the growing season, from early spring to frost and beyond in the fall. At any one time, most species will not be blooming, but many plants that bloomed prior to your visit will be producing fruits and setting seeds. Others will come into bloom later.
Grasses dominate the prairie. They furnish the matrix within which the other plants grow. Notice that the plants in flower are usually the tallest, overtopping those that are now producing fruits or those that are not yet ready to flower. Those waiting their turn will grow above those flowering when the time comes, making them better able to attract the pollinators or shed pollen to the winds. Be ready to lose yourself in contemplating the richness and variety of the prairie. And be ready to make frequent trips back to see the prairie dressed with other suits of clothes, all through the growing season from spring to fall.
Tallgrass prairie vegetation is dominated by three plant families: the grasses (Poaceae), the daisy or composite family (Asteraceae), and the legume or pea family (Fabaceae). Grasses sometimes predominate in the number of different species but always dominate in annual production. The bulk of the living material on the prairie is furnished by the grasses. Grasses have two basic growth forms. Some form sods by spreading by underground stems (rhizomes) from which upright shoots appear. Slough grass and bluejoint are excellent examples of this habit. Other grasses, particularly those that inhabit drier sites, are bunch grasses, where year-to-year spread is a fringe of growth at the margin of the plant. Prairie dropseed is a good example of this habit. Others like big bluestem and Indian grass are intermediate in sod formation. It is not uncommon to find clumps of big bluestem in a circle, which has resulted from the dying out of the center of a spreading clump while its perimeter continues to spread.
Grasses have very reduced flowers, no petals or other bright colors, and typically many flowers (called florets) in a compact to spreading tuft (inflorescence). They are wind-pollinated, shedding pollen from the stamens into the air; sticky hairy stigmas on the pistil catch the pollen, leading to fertilization and seed set.
Composites such as sunflower and aster are another important group. Typically, the largest number of species on a prairie will be from the composite family. These plants group their flowers into heads, often with only the marginal flowers of the head producing prominent petals. Forms range from the tall and robust saw-tooth sunflower to pussytoes only a few inches tall.
The third family, the legume or pea family, also has many species. Their characteristic sweetpea-type flowers, podlike fruits (seed cases), and compound leaves make them easy to identify. Their nitrogen-fixing capabilities are well known.
The remainder of the prairie flora is found in many other plant families; forty-four additional families are treated in this book. Some of the other important families are the milkweed, buttercup, rose, and figwort families. The next section lists all the species in this book by family.
Iowa’s tallgrass prairie takes different forms in various landscapes. Most of Iowa was covered by upland prairie where moisture and soil conditions were favorable for plant growth. In these conditions big bluestem, Indian grass, and prairie dropseed do well. Where the land is low-lying the soil is moist more of the time, and more moisture-loving plants thrive. Bluejoint, slough grass, and saw-tooth sunflower do well here. On even wetter sites, where the prairie begins to grade into marsh, a sedge meadow often develops. Here sedges, blue flag, and swamp milkweed are characteristic. On hilltops and ridges where the soil is thinner, little bluestem and field gold-enrod predominate. Sandy prairies have a distinct flora, with June grass, sand reed-grass, and hairy puccoon often being prominent. Dry, hilly prairies are found on both the east and west sides of Iowa. In the west the Loess Hills are a chain of hills formed from wind-blown silt stretching from north of Sioux City to below the Missouri border along the floodplain of the Missouri River. Little bluestem, side-oats grama, dalea, soap-weed (yucca), and other species able to withstand drought do well here. In the hilly portion of northeastern Iowa so-called goat prairies are often found on exposed southwest-facing slopes. Again, little bluestem dominates, along with side-oats grama and aromatic aster.
Examples of tallgrass prairie are found across the state. The largest prairies are under protection by the state of Iowa, certain counties, and private organizations. Many small remnants exist on old railroad rights-of-way, pioneer cemeteries, abandoned country school grounds, and other waste places. A partial list of prairies open to the public is given at the end of the book.
Maintaining Iowa’s prairies calls for an active role by their managers. Trees often invade prairies after periodic burning or mowing no longer takes place. Good examples are on the goat prairies of northeastern Iowa, where red cedar has overrun many small prairies. The western portion of the Loess Hills was devoid of trees prior to European settlement, according to early travelers’ reports. Now, trees and brush have invaded nearly to the tops of some of the hills. Consequently, prairie preserves and remnants are usually managed with fire or mowing to combat woody invasion and favor prairie species. Burning is often done on a two- to five-year cycle, usually in the spring, although managers are trying fall and even summer burns as well. Efforts to leave refuges for animals with small populations, such as some butterflies, by burning small sections, burning only portions of critical habitats each year, and varying the season of burn all help to maintain as wide a diversity of species as possible.
Efforts to reconstruct tallgrass prairie have been going on in Iowa since the 1950s. Learning from range reseeding in the Great Plains during the 1930s, from the experiments at the University of Wisconsin Arboretum, and from other sources, prairie enthusiasts have had considerable success. The largest reconstruction attempted in Iowa began in 1993 at Walnut Creek (now Neal Smith) National Wildlife Refuge near Prairie City, Iowa, east of Des Moines. There the federal Fish and Wildlife Service has begun to revegetate up to 8,000 acres of agricultural land with prairie and savanna. In 1997 a prairie learning center was opened, and bison were introduced to the refuge. Many school districts, parks, and other agencies, as well as hundreds of private individuals and many corporations, have done the same on a smaller scale. John Deere Corporation in Cedar Falls and the Iowa Farm Bureau at its headquarters in Des Moines are two examples. At the University of Northern Iowa in Cedar Falls a prairie has been reconstructed, as well as at Cornell College, Grinnell College, Iowa State University, and others. Prairie reconstructions are beginning to be noticed on state and county roadways as well. The Iowa Department of Transportation (DOT) began evaluating use of prairie grasses on highway rights-of-way in the 1950s. A county roadside program originated at the University of Northern Iowa in 1988 aiding county roadside managers in controlling erosion and preventing weedy growth by using prairie species. The Iowa DOT has introduced prairie grasses and flowers on primary highways in many locations across the state. Several seed and plant producers in Iowa and surrounding states have turned to prairie species to furnish materials to a growing number of persons interested in using prairie as an alternative to maintaining large expanses of mowed lawn on their properties.
We seem to have come full circle in our interest in prairies. The farmers who settled Iowa in the 1800s were intent on replacing the prairie with cropfields and pastures. Only after prairies had almost disappeared did we realize that they offered more than academic interest. We found the prairie to be a place of beauty, of utility, of historical interest, and of regeneration for our psyche.
Prairie watching is addictive. The diversity on the landscape, from shoetop to horizon, holds one’s attention to the exclusion of the passing of time and matters of pressing concern. Studying the prairie is satisfying, especially aesthetically, but also intellectually. Reading the landscape through the species present, observing the season of bloom, deciphering the structure of the flowers, recognizing the visiting pollinators, investigating the size and shape of seeds, and experiencing the thrill of germinating seedlings are all part of getting to know prairies.
I prepared the plant descriptions and distributions while on sabbatical leave from Cornell College as a fellow at University House, the University of Iowa. The distribution maps were prepared with a grant from the Living Roadway Trust Fund, Iowa Department of Transportation. The Living Roadway Trust Fund and the Iowa Science Foundation funded the preparation of illustrations.
I wish to thank Dr. Roger “Jake” Landers for introducing me to the tallgrass prairie and my wife, Barbara, and my sons, Dana and Scot, for persevering these many years with the prairie as a constant companion.
—Paul Christiansen
During the two years that I worked on An Illustrated Guide to Iowa Prairie Plants, my “office” consisted of a lawn chair and sketch pad. Traveling to nearly every prairie remnant left in the state, I intended to illustrate all the plants in their natural repose. In the end, several elusive species were drawn from herbarium specimens and photographs.
Paul and I were always amazed at the radical variability among individuals of a species as well as the similarities between certain species; this led to an expansion of the range of measurements and revisions of descriptions. The primary focus of the illustrations and descriptions is to provide anatomical detail to aid in field identification. But we hope that this book will also enhance the appreciation and care for an amazing and amazingly threatened ecosystem: the tallgrass prairie.
I would like to thank Daryl Smith and Larry Eilers for my prairie addiction, Diana Horton and Jennifer Bell of the University of Iowa Herbarium for their immense help, and Paul for inviting me along on this project. Finally, I would like to thank Valerie Cool, who offered much encouragement, patience, and great companionship on many memorable prairie forays.
—Mark Muller