The unseen world of little bluestem grasslands.
Text and Photography by Tara Mitchell
Roadsides are a tough place for any form of life. The land is never free of human disturbance, be it from mowing, drainage and guardrail repair, tree cutting, installation of signs and utility posts, or vehicles that don’t stay the course. The soils are often compacted, dry and infertile, and polluted from salt and runoff. Remnants of debris—plastic bags and bottles, fast-food wrappers, coffee cups, pieces of cardboard, toys, and miniature liquor bottles—lie tucked away in the vegetation. On heavily trafficked roads, there is the continuous roar of cars and trucks whizzing by, wearing, irritating, never-ending.
Roadside vegetation is increasingly becoming a jungle of nonnative plants. In some places, there exist impenetrable stands of Japanese knotweed and common reeds. Elsewhere, the ubiquitous jumble of bittersweet, multiflora rose, and honeysuckle eats away at the forest edge. In more suburban areas, barberry, burning bush, and English ivy, having escaped the confines of manicured landscapes, creep unnoticed through the understory, changing the soil chemistry and the ecology of adjacent forests. From the perspective of vegetation, the roadside is a double war zone: man versus nature and plant invaders versus long-established plant communities.
But sometimes, when the soils are dry and infertile and the land is sufficiently exposed to the wind and the beating sun, there exists (when the mowers allow) extraordinary beauty in long stretches of little bluestem grassland. These grasslands may not be particularly noticeable during the summer, but by late August, when the foliage turns a coppery-red hue and the fluffy white seeds glint in the sunlight, the land is transformed. When mixed with the pink haze of purple lovegrass in bloom and a sprinkling of goldenrod, rabbit tobacco, and aster, the combination can be stunning.
Little bluestem (Schizachyrium scoparium), along with big bluestem, Indiangrass, and switchgrass, was one of the dominant warm-season prairie grasses of the Great Plains, an extensive band of grassland that once ran through the Midwest from Canada to Mexico. In New England, little bluestem grows in exposed rocky outcrops, in the acidic, sandy soils of the coastal sand plains and heathlands, and in the dry, neglected lands of roadsides, railroads, and abandoned lots. Without fire, grazing, or mowing, little bluestem, like any grassland, is transitional. Eventually, given sufficient moisture, woody species move in. On the roadsides, where a clear zone of no trees over four-inch caliper is required for safety, mowing prevents succession to forest.
When managed as grassland, little bluestem is an ideal roadside grass. Its qualities are readily visible: It is low-growing, erect, and compact, all valuable aesthetic characteristics. While it is most ornamental in the fall, the summer foliage is an attractive blue-green, often streaked with crimson. Growing in clumps that reach one to three feet in height, depending on soil fertility and moisture, the foliage doesn’t block sight distances or hang over guardrails. As a small clump grass, it is easy to mow at mature height, unlike the taller, denser clumps of switchgrass, big bluestem, and Indiangrass, making it ideal for limited mowing.
But it is what we cannot see that makes little bluestem so important as a roadside grass. Unlike the more shallow-rooted lawn grasses, little bluestem has an extensive, fibrous root system that extends deep into the earth as well as laterally through the upper soil. Aboveground, the widely spaced clumps may give the appearance of sparse vegetation, but underground is a dense network of roots extracting soil and nutrients. The fine branching nature of the roots allows them to penetrate into tiny crevices in rock and compacted soils, giving little bluestem a competitive edge over plants with coarser roots.
This dense root system holds soil in place, preventing sediment from washing into waterways and catch basins. As individual roots seek moisture and nutrients, they create passageways in the soil, allowing water and oxygen—key ingredients for life—to infiltrate. When these roots die, the organic matter left behind increases, and thus the water-holding capacity of the land increases over time. With more water infiltrating and being absorbed within the grassland, less water ends up in roadways and drainage systems.
Highly functional as a roadside grass, little bluestem also provides an important ecological function in that it paves the way for change in the land. As living and dead roots increase, more food becomes available for organisms such as fungi, ants, worms, and ground beetles. The activity of these organisms creates and releases more nutrients that are then available for plant uptake. Over time, infertile land, once uninhabitable, becomes available for colonization by new species.
At first glance, many little bluestem stands appear to be fairly pure, containing few other plant species. But walking slowly through the grasses along the roadsides of Massachusetts, where I am a landscape designer with the Massachusetts Department of Transportation, I find hidden within the depths a surprising amount of diversity. One of the most common and important forbs, and among the earliest to show up, is roundhead lespedeza (Lespedeza capitata). Like little bluestem, roundhead lespedeza is well-adapted to dry soils. However, instead of relying on an extensive root system, roundhead lespedeza sends down a long taproot to access moisture and nutrients deep in the earth. Like other plants in the Fabaceae family (legumes), roundhead lespedeza has a symbiotic relationship with nitrogen-fixing bacteria, giving it a competitive advantage in nutrient-poor soils. When the roots and foliage of roundhead lespedeza die, nitrogen is added to the soil. Thus, roundhead lespedeza is an important participant in the gradual transition of grassland to forest.
Other typical forbs include goldenrod, rabbit tobacco, yarrow, and aster. Depending on moisture and level of disturbance, a variety of less conspicuous flowers can be found in the understory. Often these are weedy, nonnative species, but in one instance I found forked bluecurls (Trichostema dichotomum), a native species that I had never seen before. Named for its lovely, delicate blue flowers with distinct curled stamens, forked bluecurls is an annual in the mint family.
Purple lovegrass (Eragrostis spectabilis) and poverty oatgrass (Danthonia spicata), both low-growing grasses, are typical, growing in the hollows between the bluestem clumps. Purple lovegrass, in particular, is well-adapted to roadside conditions and is the only grass able to thrive in the frequently mowed, infertile, and polluted soils adjacent to the pavement.
Easy to overlook, mosses and lichens find their niche on the soil surface. Lying dormant during hot, dry periods, these species spring to life when the rains come. They absorb and retain water like sponges and maintain humidity within the grassland. Mosses and lichens are essential to the process of succession, and they provide a moist substrate for the seeds of wildflowers and woody plants.
Left to its own devices, a little bluestem grassland will eventually evolve into densely layered compositions of sweet fern, lowbush blueberry, eastern red cedar, pine, oak, and birch typical along many New England roadways. Over the course of thousands of years, this tight-knit and fairly selective community of plants has figured out the perfect formula for creating a complex, evolving, and enduring system of life from the most basic components of barren land.
Grassland is the domain of insects. Within the dense forest of blades, short lives are lived with a frenzy of intensity. With few wildflowers, little bluestem stands are the realm of grazers and predators rather than pollinators. As I walk through a well-established stand on a September morning, it is quickly evident to me that grasshoppers dominate the grassland. With every step, they leap ahead of me, their raspy chorus rising above the sound of the traffic. Like plankton in the sea, these ancient herbivores form an abundant food source that supports numerous other species.
Most obvious on that list are the variety of garden spiders (Argiope), members of the orb weaver spider family (Araneidae). These large, brightly colored, yellow and black spiders with their classic, circular webs are easy to spot and identify. The thick zigzag pattern that typically runs through the web (the stabilimentum) provides another clue. Walking carefully so as to avoid undoing their morning’s work, I come across dozens of webs, each with a spider intent on some stage of the life and death process: constructing her web, struggling with a freshly entangled grasshopper, wrapping victims, or simply waiting for the action to begin.
Beneath my boots, made visible only by the hundreds of small anthills, a separate but related universe churns away. I never see ants on the roadside, but their little hills are common in dry soils. Ants are like farmers. As they build and maintain their underground nests, they redistribute organic matter and nutrients within the soil profile, moving topsoil down and mineral soil up, essentially tilling the soil. In the process, they move seeds, thus planting and determining the future composition of the grassland.
Grasslands are home not only to a host of insects living within the foliage and roots, but also to fungi. There are beneficial fungi—mycorrhizal fungi that colonize plant roots, providing nutrients and moisture—and then there are fungal predators. If I didn’t already know a bit about fungi, I might have missed a parasitic presence, possibly Entomophaga grylli. The fungus was perhaps gone, but the ghostly shell of its host remained, clinging to the top of a blade of grass. Entomophaga grylli is parasitic on grasshoppers and has evolved the amazing ability to induce its grasshopper host to climb to the top of the plant. There the grasshopper clings until it dies, allowing the fungal spores optimum dispersal across the grasslands upon leaving the corpse.
With so much life visible on my brief stop, it’s hard to imagine how many thousands of insects and other creatures exist without witness. If not for a close-up photo of a grasshopper, I would not have known of the existence of scelionid wasps, small wasps that are parasitic on grasshoppers and their eggs—unfortunate for the grasshopper, but, like the fungal parasites, necessary to keep the grassland system in balance. In addition to being the home of countless insects, grasslands provide a source of food and nesting material to unknown numbers of visitors passing through, from pollinating bees and butterflies to damselflies and dragonflies, aerial predators that zip and hover about the grasses in search of prey. With dusk, the scene will change as crickets take the place of grasshoppers and unknown insects of the night surface.
Grasslands are evolving systems. They change over time, in generally predictable ways, to forest. But now, larger global factors are bringing unprecedented shifts. Climate change promises both wetter and drier conditions. With too much rain or extreme drought, little bluestem and the species it supports may disappear. By my observations, the tightly knit little bluestem plant community is resistant to invasive plants. But it is not immune. Spotted knapweed has invaded many roadside stands and is spreading rapidly. Knapweed reduces species diversity and consequently diminishes soil stabilization, water-holding capacity, and carbon cycling in the land. With new threats and an increasingly altered environment, long-established plant communities and systems, once self-reliant, will be more dependent upon humans for their continued existence.
Driving along the highway, we may look upon little bluestem grasslands as just another stretch of grass—weeds, if they haven’t been mowed into lawn. But they protect our infrastructure—our roadways and waterways—and thus our own system of life. As we develop and pave more and more land, we need vegetation that can survive on poor soils and in harsh, exposed conditions. And to survive, little bluestem needs to mature through the season so that it can absorb sufficient energy from the sun to support its extensive root system and produce the seeds that ensure the continuation of the grassland into the future. The sooner we shift to practices that preserve and protect these lands and systems, the better off we will be, for so much depends upon these forests of blades.
Tara Mitchell is a landscape designer at the Massachusetts Department of Transportation’s Highway Division.