Grasses of the Tallgrass Prairie
(Editor's Note: This article was originally published on September 15, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
A prairie is, first of all, a grassland. At least half of a natural prairie's plants are grasses. The tallgrass prairie takes its name from two grasses that spectacularly dominate the late-summer prairie landscape: Big Bluestem and Indiangrass. These grasses can often reach eight feet or more in height. But there are many shorter varieties of native prairie grass that are also worthy of interest.
Most prairie grasses are hardy warm-season perennials, well adapted to the extremes of their climate — subzero winters and burning dry summers. Their root systems run deep into the soil to enable them to withstand drought and fire. Many of them are clumping plants. After the prairie is burned in the spring, you can see the black hummocks that will soon sprout new green leaves. By midsummer, the prairie has become a sea of grass.
Big Bluestem [Andropogon gerardii]
This grass is a dominant species in the tallgrass prairie, so much that some prairies were called bluestem prairies, where the grass formed a dense sod that excluded other plants. However it also grows in clumps. It is usually the tallest grass in the prairie where it grows, sometimes to nine or ten feet in height. It takes its name from the blue-green color of its stiff, rounded stems. In the fall, the stems and foliage turn an attractive burgandy red.
The shape of the seedheads is quite distinctive, typically with three long spikes. This feature gives it the taxonomic name that means "turkey foot." As a warm-season grass, like most on the prairie, it flowers in late summer.
Indiangrass [Sorghastrum nutans]
This grass is nearly the equal of Big Bluestem in height, and the two species often grow as companions, as they prefer the same growing conditions. The stems and leaves of Indiangrass are lighter than Blue Bluestem and actually even more blue in color. It has a clumping habit of growth and is less of a sod-forming grass than Big Bluestem. Both are warm-season grasses and flower at the same time, in late summer. This is when it is easiest to tell the two species apart, as the form of their seedheads is quite different. The yellow anthers of the Indiangrass flowers can be quite noticeable in a meadow full of this grass. Later in the fall, the color turns an attractive bronze.
Switchgrass [Panicum virgatum]
This grass is of medium height, about four to six feet. It is a common species in the tallgrass prairie, where it tends to form sod rather than clumps. The leaves are somewhat broader than those of the taller grasses. It flowers in late summer, along with Big Bluestem and Indiangrass. The flower heads are very slender and branching, with extremely small, inconspicuous flowers that have a delicate appearance.
Little Bluestem [Schizachyrium scoparium]
This mid-height grass was once classified as a close relative of Big Bluestem, but is now considered to be in a different genus. It has a strong clumping habit with narrow leaves, growing to no more than four feet. It is a very vigorous grass that is common in both the tallgrass and shortgrass prairies and resists drought. The seed spikes are rather inconspicuous.
Prairie Dropseed [Sporobolus heterolepis]
This short bunching grass is one of the dominant species of some tallgrass prairies, as well as the shortgrass region. It is an extremely attractive grass, forming a dense clump of very fine green leaves that have a fountain appearance. Many of the hummocks visible after a prairie burn are Pairie Dropseed. The seedheads rise above the clump on very slender stalks, so fine they are almost invisible.
Sideoats Grama [Bouteloua curtipendula]
This sod-forming shortgrass is more abundant in the drier prairie regions than the tallgrass prairie, where it is often shaded out by taller plants. It is quite drought resistant. The grass itself is not particularly attractive, but it is notable for the way its flowers hang from one side of the stalk, and the seeds that remain for much of the fall after blooming in late summer, earlier than the common tallgrass species.
Canada Wild Rye [Elymus canadensis]
While the most important grass species in the tallgrass prairie are warm-season grasses that bloom in late summer, there are also cool-season varieties. This medium-height grass is more common to disturbed sites than well-established prairies. Its most prominent feature are its gracefully nodding seed spikes, which resemble the cultivated grain, to which it is not closely related.
Prairie Brome [Bromus kalmii]
A cool-season grass, one of the earliest to bloom on the prairie. While native to the northern tallgrass region, it is not one of the most common prarie species, and not very noticeable.
Prairie Cord Grass [Spartina pectinata]
This coarse, warm-season grass colonizes wet and marshy areas where the more common prairie grasses do not thrive. In such conditions, it forms a very dense sod that excludes other plants. The leaves are very tough with serrated edges that can cut the skin.
Blue Joint Grass [Calamagrostis canadensis]
Another species that colonizes areas of moist soil, forming dense clumps. The leaf blades are long and fine. This is a cool-season grass that blooms in early summer.
Gardeners interested in a prairie restoration project or a home pairie garden should definitely consider some of these native species. There are prairie grasses of all sizes, suitable for a variety of growing conditions. Many of them are attractive ornamental grasses. A growing number of vendors are offering plugs that will help your grasses get off to a good start at recreating a prairie in your own garden.
References: Kirt, Russell R., Prairie Plants of the Midwest. Stipes Publishing LLC, Champaign, IL, 1995
Ladd, Doug and Oberle, Frank, Tallgrass Prairie Wildflowers. Morris Book Publishing LLC, Guilford, CT, 2005