The Grass Beneath the Game: From Botanical Drawings to the NFL Field

As Pittsburgh prepares to welcome the NFL Draft, attention turns to the spectacle on the field, but also to the field itself. At Acrisure Stadium, a transition from Kentucky bluegrass to a newly engineered bermudagrass reflects ongoing innovations in how we design and maintain playing surfaces in cold-weather climates.

Long before these modern turf systems, scientists and illustrators were documenting the grasses that form the foundation of today’s landscapes, from stadium fields to campus lawns. Drawing on the Hunt Institute for Botanical Documentation’s extensive collections, Curator of Art & Research Scholar Lydia Rosenberg explores the botanical history and structure of these familiar yet highly engineered plants.

In this guest essay, she connects historic grass illustrations and agricultural research to the fields and lawns beneath our feet, revealing how centuries of study still shape the landscapes around us today.

Since the former Heinz Field, now Acrisure Stadium, opened in 2001, it has used plants – real, living grasses – to cover the field. For the last 25 years, the primary species of grass used to make the field has been the familiar and ubiquitous Kentucky bluegrass, a grass also present in the mixture used on CMU’s campus lawnscapes. In February, Acrisure Stadium announced its intention to replace bluegrass with a new mixture called Tahoma 31 bermudagrass, a cold-hardy cultivated grass turf developed at Oklahoma State University that has been adopted by other fields like those at the Philadelphia Eagles and Chicago Bears stadiums. Since Acrisure plans to make this change before the next season begins, coinciding with the NFL Draft in Pittsburgh and the reappearance of weather fine enough for lounging on the lawn, it is timely to look into the species of grasses from which these cultivated and engineered green expanses are developed.

In The Manual of the Grasses of the United States (1935), Albert Spear Hitchcock (1865-1935) who in his various roles at the USDA, lead an incredible and highly successful effort to collect, identify and document as many grasses of the world as possible, notes in the first lines of his book, the significance of grasses for human life. “Of all the plants of the earth the grasses are of the greatest use to the human race […] The grasses furnish the principal breadstuffs of the world and a large part of the food of domestic animals; they are also used in the industrial arts and extensively as greensward and ornamentals in parks and gardens.” Hitchcock, A. S. Manual of the Grasses of the United States. U.S. Department of Agriculture Miscellaneous Publication No. 200. Washington, DC: Government Printing Office, 1935.

The black and white illustrations in this article were made during or before Hitchcock’s time at the USDA and are part of a large collection of 2,713 drawings of grasses on indefinite loan from the Smithsonian Institution to Carnegie Mellon University’s Hunt Institute for Botanical Documentation. All of the drawings are digitized and in the public domain and can be found in various grass-related publications, many produced during Hitchcock’s tenure at the USDA.

Hitchcock writes in the same volume that “the grasses of the world (about 510 genera) have been grouped into 14 tribes, all of which are represented in the United States.” With so many genera, let alone our species count and the cultivars and hybrids, what makes a certain grass better for a football field than another?

Both bluegrass and bermudagrass are dominant in the “field” so-to-speak of lawns, sports field surfaces and pasture alike, and there are others commonly used on playing surfaces such as tall fescues and rye grasses. A lot depends on the climate, the game, and of course the budget and labor to maintain it. Here in Pittsburgh, and in other regions with cold weather patterns, varieties are required that can survive the cold temperatures. At Acrisure Stadium, the field is heated from below, allowing the grass to stay around 62 degrees and maintain its rich green color through below-freezing temperatures. But what makes these varieties and others like them, including those used in the latest, Tahoma 31 bermudagrass, so successful is actually part of the way the plant naturally grows. Bluegrass and bermudagrass share a rhizomatic root structure, sending out underground networks that create a dense sod which helps the grass spread evenly and recover from heavy traffic. What is remarkable about these grasses and makes them such successful field fodder is that the plant grows from the base of the stem, as opposed to growing from the tip of the stem, an evolutionary mechanism that allows grazing animals to eat the green leaves without damaging the anatomical element required for growth. So if the grass is the right variety, “Mo” CMU’s mower robot can trim the grass as low as that point, known as the “intercalary meristem” which in the case of Kentucky Bluegrass can be as low as ¾ of an inch according to Cornell University’s College of Agriculture and Life Sciences.

Thanks to our friends at the university’s Facilities Management Services, we were able to learn about the blends used at CMU, which contain a mix of Tall Fescue (Festuca arundinacea Schreb.) and Kentucky Bluegrass. The new blend being used in the 2026-2027 season of Steeler’s football will be, as mentioned, Tahoma 31 bermudagrass, a hybrid grass engineered for its cold hardiness. For a closer 'touch-the-grass' moment, examine the historic descriptions and illustrations of the native grass species from which our engineered lawns and fields are derived.

Kentucky Bluegrass or just Bluegrass is known in the botanical world as Poa pratensis L. It has found great success in use for landscaping, lawns, and sport surfaces, as well as making an excellent grass for pasture- grazing animals.

“Botanical Name: Poa pratensis L. The genus Poa includes the species of bluegrass of which there are about 100, found in all the cooler parts of the world. Only a few of these have been brought into cultivation, the species under consideration being by far the most important. Poa is a word used by the ancient Greeks for grass in general, but Linnaeus adopted the name for the genus as now understood. The term pratensis means growing in meadows.” Hitchcock, Albert Spear. 1921. A manual of farm grasses. Washington: Hitchcock.

Bermudagrass, sometimes called “wire grass” has a similar use history to bluegrass and seems to share essentially similar use values although it is notable that one synonym (a name that refers to the same plant species) is Capriola meaning goat in Latin.

“Botanical Name.—Capriola dactylon (L.) Kuntze; Cynodon dactylon Pers.; Panicum dactylon L. There is but one common species of the genus and this is widely distributed in the warm regions of both hemispheres. The name Capriola comes from a Latin word for goat, probably given because goats feed on the grass. The specific name dactylon is a reference to the inflorescence, from the Greek word for finger, the spikes spreading from one point like the fingers on the hand. The other generic name, Cynodon, in common use, means dog-tooth, given probably because of the old pointed sheaths on the stolons and rootstocks. The giant Bermuda is Capriola dactylon var. maritima.” Hitchcock, Albert Spear. 1921. A manual of farm grasses. Washington: Hitchcock.

So next time you stain your knee catching a pass in the end zone, or lay out a picnic blanket on the lawn, enjoy the robust support only certain grass species can offer.

Located on the fifth floor of Hunt Library, the Hunt Institute for Botanical Documentation at Carnegie Mellon University preserves and shares one of the world’s leading collections of botanical art and literature, making these materials accessible for research and public exploration. The current exhibition is "To Make a Prairie: Pollination and Human Understanding," running March 17 through June 30.