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Aristida purpurea var. purpurea (Purple threeawn)
San Antonio River Authority

Aristida purpurea var. purpurea

Aristida purpurea Nutt. var. purpurea

Purple Threeawn, Red Threeawn

Poaceae (Grass Family)

Synonym(s): Aristida purpurea var. laxiflora, Aristida roemeriana


USDA Native Status: L48 (N)

Vegetatively similar to Aristida purpurea, culms erect and 15-70 cm. tall. Panicles: narrow but loose, 5-18 cm. long with small, delicate spikelets.


From the Image Gallery

1 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Grass/Grass-like
Root Type: Fibrous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Leaf Shape: Linear
Leaf Venation: Parallel
Inflorescence: Panicle
Fruit Type: Caryopsis
Size Notes: Up to about 28 inches tall.
Autumn Foliage: yes
Fruit: Reddish purple.

Bloom Information

Bloom Color: Green , Purple , Brown
Bloom Time: Feb , Mar , Apr , May , Jun , Jul , Aug , Sep
Bloom Notes: Best appearance of flower when backlit by sunlight


USA: AR , AZ , CA , CO , KS , LA , NM , NV , OK , TX , UT
Native Distribution: Texas north to Utah, Colorado and Kansas, south to northern Mexico.
Native Habitat: Dry hills and plains, sandy or clayey soils.

Growing Conditions

Water Use: Low
Light Requirement: Sun
Soil Moisture: Moist
Cold Tolerant: yes
Heat Tolerant: yes
Conditions Comments: Native clumping grass with fine textured leaves and purple flowers that are showy when the sunlight illuminates them in the summer and fall. It is drought tolerant and cold hardy to about 10 degrees F. Looks its best when grown with moisture and better garden soils. Wait to prune off dormant foliage unitl spring to enjoy winter structure. Combines well with annuals and perennials and adds softmess to the garden. The seeds have sharp points and will embed themselves into your socks.


Use Ornamental: Beautiful garden grass with delicate, showy purple seed heads.
Use Wildlife: Seeds for birds.
Conspicuous Flowers: yes
Interesting Foliage: yes
Attracts: Butterflies
Larval Host: The Grass Family is an essential larval food for most branded skippers and most of the satyrs.
Deer Resistant: Moderate

Value to Beneficial Insects

Provides Nesting Materials/Structure for Native Bees

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.


Propagation Material: Seeds
Description: Seed in spring
Seed Treatment: No special pre-treatment.
Commercially Avail: yes
Maintenance: If plant becomes ratty in appearance, cut back to 4" to refresh. Remove seed heads before they mature if seedlings are not desired.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Lady Bird Johnson Wildflower Center - Austin, TX
NPSOT - Austin Chapter - Austin, TX

Herbarium Specimen(s)

NPSOT 0805 Collected May 29, 1994 in Comal County by Mary Beth White

1 specimen(s) available in the Digital Herbarium

Web Reference

Webref 30 - Calflora (2018) Calflora
Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Aristida purpurea var. purpurea in USDA Plants
FNA: Find Aristida purpurea var. purpurea in the Flora of North America (if available)
Google: Search Google for Aristida purpurea var. purpurea


Record Modified: 2022-11-23
Research By: MWJ

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