North America Native Plant

Knot Grass

Botanical name: Setaria reverchonii firmula

USDA symbol: SEREF

Life cycle: perennial

Habit: grass

Native status: Native to the lower 48 states  

Synonyms: Panicum firmulum Hitchc. & Chase (PAFI10)  âš˜  Setaria firmula (Hitchc. & Chase) Pilg. (SEFI)   

Knot Grass: A Little-Known Native Texas Prairie Gem If you’re on the hunt for authentic native grasses to complete your prairie garden or naturalized landscape, you might have stumbled across knot grass (Setaria reverchonii firmula). This perennial grass is one of those quiet natives that doesn’t make a big fuss ...

Knot Grass: A Little-Known Native Texas Prairie Gem

If you’re on the hunt for authentic native grasses to complete your prairie garden or naturalized landscape, you might have stumbled across knot grass (Setaria reverchonii firmula). This perennial grass is one of those quiet natives that doesn’t make a big fuss but has been quietly holding down fort in Texas and Oklahoma prairies for ages.

What Exactly Is Knot Grass?

Knot grass belongs to the Setaria genus, which includes various bristlegrass species. As a true native to the American Southwest, this perennial grass has earned its place in the local ecosystem over thousands of years. You might also see it referenced by its scientific synonyms Panicum firmulum or Setaria firmula in older botanical references.

Like other members of the grass family, knot grass is what botanists call a graminoid – essentially a grass or grass-like plant that forms the backbone of prairie ecosystems.

Where Does Knot Grass Call Home?

This grassland native has a fairly limited range, naturally occurring in Oklahoma and Texas. If you live in these areas, you’re looking at a plant that’s perfectly adapted to your local conditions and climate.

Should You Plant Knot Grass in Your Garden?

Here’s where things get a bit tricky – knot grass is one of those native species that hasn’t made it big in the gardening world yet. While it’s definitely a legitimate native choice for Texas and Oklahoma gardeners, detailed growing information is surprisingly scarce.

The Good News:

  • It’s a true native, so you’re supporting local ecosystems
  • As a perennial, it should return year after year once established
  • Native grasses typically require less water and maintenance than non-natives
  • Perfect for prairie restoration or naturalized areas

The Challenge:

  • Limited availability in nurseries
  • Scarce detailed growing information
  • May be difficult to source seeds or plants

Growing Knot Grass Successfully

While specific care instructions for knot grass are limited, we can make educated guesses based on its native habitat and related species:

Growing Conditions

Since this grass naturally occurs in Texas and Oklahoma prairies, it likely prefers:

  • Full sun exposure
  • Well-draining soils
  • Moderate to low water requirements once established
  • USDA hardiness zones 6-9 (based on its natural range)

Best Uses in the Landscape

Knot grass would likely work well in:

  • Prairie gardens and native plant landscapes
  • Naturalized areas where you want authentic regional flora
  • Wildlife habitat restoration projects
  • Areas where you want low-maintenance, drought-tolerant groundcover

Wildlife and Ecosystem Benefits

While specific wildlife benefits for knot grass aren’t well-documented, native grasses generally provide important ecosystem services. They offer habitat and food sources for various insects, birds, and small mammals. The seeds likely feed birds, and the grass structure provides nesting materials and shelter.

The Bottom Line

Knot grass represents an interesting choice for the adventurous native plant gardener in Texas or Oklahoma. While it may not be the showiest grass in your garden, it offers the satisfaction of growing something truly local and authentic to your region.

If you’re serious about prairie restoration or creating habitat for local wildlife, tracking down this native grass could be worth the effort. Just be prepared to do some detective work to find seeds or plants, and don’t expect to find detailed growing guides at your local garden center.

For those wanting native grass alternatives that are easier to source and grow, consider other regional natives like buffalo grass, little bluestem, or sideoats grama, which offer similar benefits with more readily available growing information.

Knot Grass

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Commelinidae

Order

Cyperales

Family

Poaceae Barnhart - Grass family

Genus

Setaria P. Beauv. - bristlegrass

Species

Setaria reverchonii (Vasey) Pilg. - Reverchon's bristlegrass

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA