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Purple Three Awn
Aristida purpurea

About Purple Three Awn (Aristida purpurea) Aristida purpurea is a species of grass native to North America which is known by the common name purple three-awn. This grass is fairly widespread and can be found across the western two thirds of the United States, much of southern Canada and parts of northern Mexico. It is most abundant on the plains. In California it is found primarily from Mono County southwards, in desert, mountain and coastal habitats. This is a perennial grass, growing erect to under a meter in height, and the flower glumes often assume a light brown to reddish-purple color. There are several recognized varieties with overlapping geographical ranges. This is not considered to be a good graze for livestock because the awns are sharp and the protein content of the grass is low. However, it makes an attractive landscape grass that is a good substitute for invasive, non-native grasses.
Plant Description
Plant Type

Max. Height
1.6 - 3.3 ft (0.49 - 1 m)

Max. Width
2 ft (0.6 m)




Flower Color
Cream, Purple, Red, Brown

Flowering Season
Spring, Winter

Native Status

Natural Setting
Site Type
Sandy or rocky soils, slopes, plains


Elevation ?
92' - 7251'

Annual Precip. ?
2.6" - 34.1"

Summer Precip. ?
0.15" - 3.28"

Coldest Month ?
32.9° F - 63.2° F

Hottest Month ?
61.8° F - 88.8° F

Humidity ?
1.19 vpd - 42.80 vpd

Soil Description
Tolerates a variety of soils

Soil PH
6.5 - 7.5

Fast, Medium

Cold Tolerance(° F)
Tolerates cold to -20° F

Companion Plants
Can be used with a very wide variety of other plants from the mountains, deserts or coast. Examples include Creosote Bush (Larrea tridentata), Sagebrush (Artemisia sp.), Joshua Tree (Yucca brevifolia), Brittlebush (Encelia sp.), Buckwheat (Eriogonum sp.), and various cactus and succulent species.

Landscaping Information
Ease of Care
Very Easy

Water Requirement ?
Very Low
Extremely Low
Very Low
Moderate - High

Moderately Popular

Max. Summer Water ?
No Summer Water
Keep moist

Avoid cutting back the plant if possible. Remove old seed heads by gently pulling.

Propagation ?
By seed. This plant readily seeds itself and like other grasses it can be mildly invasive in the garden. New young plants can be easily removed by pulling.

Common uses

Nursery Availability
Commonly Available

Other Names
Common Names
Purple Three-awn, Purple Threeawn

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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