SafePlants

Purple Three-Awn (Aristida purpurea)

Aristida purpurea, commonly known as purple three-awn, is a species of grass native to North America. Other common names include red threeawn, purple 3-awn and fendler threeawn.

Considerations for Pets

• The plant has three-awned seed heads, which could potentially cause minor physical irritation if they come into contact with a pet's skin or eyes.

Taxonomy and Nomenclature

• Scientific Name: Aristida purpurea Nutt.
• Family: Poaceae (Grass family)
• Synonyms: Alternative scientific names include Aristida.
• Taxonomic Notes: Aristida purpurea has been considered a complex of about eight species, but has been reduced to one species with seven varieties.

Distribution and Habitat

• Native to North America.
• Fairly widespread.
• Found in the deserts around Las Vegas.
• Commonly found in fair-poor condition rangelands, particularly in south Texas.
• Also found on the Edwards Plateau, where limestone meets gravels.
• It can be spotted in small patches throughout Southern California.

Ecological Role

• Capable of increasing on rangelands, forming near monocultures, and creating a stable state. This suggests it can be invasive under certain conditions.
• Often found in overgrazed or disturbed areas.

Morphological Characteristics

• Perennial bunchgrass.
• Grows in individual clumps.
• Height: Typically 12 to 24 inches tall, or 1 to 2 feet tall. Some sources mention up to 30 inches.
• Culms (stems): Erect, tufted, 6 to 30 inches tall, glabrous, hollow.
• Leaves: Fine-textured, mostly basal, rolled inward or flat, 1 to 12 inches long, less than 1/10 inch wide. Leaves can grow up to 5 inches long.
• Flowers: Attractive purple flower heads (inflorescences) that form a cloud of purple in summer. Reddish-purple nodding, narrow panicles. The seed head carries the seed and has a 3-spoked (3-awned) pinwheel shape.
• Stems and flowers can have a purple tint, especially where it grows abundantly.
• Densely tufted.

Interactions with Other Organisms

• A plant pathogenic urediniomycete fungus has been described from three-awn grass.

Additional Information

• Forage value depends largely on the other species present. Provides poor grazing for wildlife and fair grazing for livestock.
• Popular among horticulturalists for use in gardens.
• Sunset zones / USDA zones: 8-10.

Quirky Facts

• One source playfully suggests that when viewing the purple inflorescences (grass flowers), a dreamer can imagine that the earth has purple hair.