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Native Plant Society of Texas

Purple Threeawn

Aristida purpurea

Other common name(s):

Purple 3-awn, Purple Three-awn, Red Threeawn

Family:

Poaceae (Grass Family)

Plant Ecoregion Distribution Map

This map uses data from the US EPA. EPA  servers have been offline frequently so maps may not display. We are working on a solution.

Central Great Plains, Chihuahuan Deserts, Cross Timbers, East Central Texas Plains, Edwards Plateau, Gulf Coast Prairies and Marshes, High Plains, Southern Texas Plains, Southwestern Tablelands, Texas Blackland Prairies
Broken Red Plains, Limestone Plains, Red Prairie
Chihuahuan Basins and Playas, Chihuahuan Desert Grasslands, Chihuahuan Montane Woodlands, Low Mountains and Bajadas, Stockton Plateau
Carbonate Cross Timbers, Eastern Cross Timbers, Grand Prairie, Limestone Cut Plain, Western Cross Timbers
Bastrop Lost Pines, Floodplains and Low Terraces2, Northern Post Oak Savanna, Northern Prairie Outliers, San Antonio Prairie, Southern Post Oak Savanna
Balcones Canyonlands, Edwards Plateau Woodland, Llano Uplift, Semiarid Edwards Plateau
Coastal Sand Plain, Floodplains and Low Terraces4, Laguna Madre Barrier Island and Coastal Marshes, Lower Rio Grande Alluvial Floodplain, Lower Rio Grande Valley, Mid-Coast Barrier Islands and Coastal Marshes, Southern Subhumid Gulf Coastal Prairies, Texas-Louisiana Coastal Marshes
Arid Llano Estacado, Canadian/Cimarron High Plains, Llano Estacado, Rolling Sand Plains, Shinnery Sands
Northern Nueces Alluvial Plains, Rio Grande Floodplain and Terraces, Semiarid Edwards Bajada, Texas-Tamaulipan Thornscrub
Canadian/Cimarron Breaks, Caprock Canyons Badlands Breaks, Flat Tablelands and Valleys, Semiarid Canadian Breaks
Floodplains and Low Terraces1, Northern Blackland Prairie, Southern Blackland Prairie

Plant Characteristics

Growth Form

Grass & Sedge

Height

1
to
2
ft.

Spread

1
to
2
ft.

Leaf Retention

Semi Evergreen

Lifespan

Perennial

Habitat and Care Requirements

Soil Type(s)

Sand, Rocky, Dry

Light Requirement

Sun

Water Requirement

Low

Native Habitat

Grassland

Bloom and Attraction

Bloom Color

Purple

Bloom Season

Spring, Summer, Fall

Seasonal Interest

Seeds, Nectar, Larval Host, Nesting Material

Wildlife Benefit

Butterflies, Birds

Maintenance

Drought tolerant. Purple three-awn is an early successional species. This low-growing prairie grass is good for erosion control on banks and provides a root matrix for many wildflower species. Native habitat: rocky or sandy plains and slopes, Found commonly along roadsides from 1,000-7,000 ft. Easily self-seeds.

Description

Blooms April-October. Erect, small warm-season, bunchgrass. Leaves are rolled, thread-like and often have curved blades. Leaf retention depends on the region. The seedhead is narrow and nodding with lax, purplish branches. Three long, bristles occur from each flower. Awns can cause abscesses to the mouths and nostrils of grazing animals and injury to skin when caught on fur. Larval Host: Skippers, Satyrs.

References

Learn about how to propagate Texas native plants.

Material Treatment Method Collection References
Seed No Treatment Can be direct sown into the soil outddoors. Best time to sow seeds is during July. It takes about 4 months to grow. Seeds grow roots fast. After 30 days, the roots are approximately 19 inches. Establishment occurs during the warm temperatures of the summer time and with the help of fall time rain. Seeds are extremely accessible, can be collected straight from the flowering of the grass. Seeds can be collected once the grass has established flowers (dried). Seeds are hand collected into woven bags from small lots. Storage is done through cold storage at about 33-38 degrees Fahrenheit. https://courses.washington.edu/esrm412/protocols/2017/ARPU9.pdf

About the Region

2026 Fall Symposium Logo

This low-elevations region of Texas extends inland from the barrier islands, about 60 or so miles, and stretches from Brownsville to Louisiana. In total, it covers about 9.5 million acres, with a high point of 150 feet in elevation. More than 1000 species of plants can be found in this region. On the southern end, species more common in Mexico (such as Sabal mexicana) and Central America occur.

The barrier islands provide us with dune systems, and clay flats to the inland side, which have species found in these areas alone. Many plants here, such as Ipomoea pes-caprae (beach morning glory), can be found throughout tropical regions of the globe. I’ve encountered the same species on the beaches of Guam.

Once inland, vast marshes and wet prairies occur. Occasionally, oak (Quercus fusiformis) groves can be found. Common grasses include species of Bothriochloa, Paspalum, and Sporobolus; eastern gamagrass (Tripsacum dactyloides); and switchgrass (Panicum species). Many rivers and creeks cut through the Gulf Prairies, and along these riparian areas various species of trees, Sabal minor, and other plants adapted to clay soils can be found. Due to overgrazing, farming, and fire suppression, woody species such as mesquite (Prosopis glandulosa) and huisache (Acacia farnesiana), and invasive species such as chinaberry (Melia azedarach), Brazilian pepper (Schinus terebinthifolius), and Chinese tallow (Sapium sebiferum) have increased and displaced our native flora.

Source: Wildflowers of Texas by Michael Eason