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Erioneuron pilosum (Hairy woollygrass)
Anderson, Wynn

Erioneuron pilosum

Erioneuron pilosum (Buckley) Nash

Hairy Woollygrass, Hairy Tridens

Poaceae (Grass Family)

Synonym(s): Tridens pilosus, Uralepis pilosa

USDA Symbol: ERPI5

USDA Native Status: L48 (N)

Blades: Thick, narrow, flat, glabrous or hispidulous, 2-8 cm. long, 1-2.5 mm broad. Thick white margin, pointed tip. Culms: 10-30 cm. tall, typically with only 1 node elevated above the basal clusters of leaves. Inflorescence: Contracted panicle or raceme mostly 2-3 cm. long and 10-16 cm broad with 4-9 large, pale spikelets. Fruits: Caryopsis 1.3-1.5 mm. long.


From the Image Gallery

13 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
Leaf Pubescence: Glabrous
Inflorescence: Panicle
Fruit Type: Caryopsis
Size Notes: This is a low, to about 1 foot tall, tufted perennial with a lovely fluffy inflorescence that is nice in a short grass prairie garden.

Bloom Information

Bloom Color: Brown
Bloom Time: Apr , May , Jun , Jul , Aug , Sep , Oct


USA: AZ , CA , CO , KS , NM , NV , OK , TX , UT
Native Distribution: Abundant in far West Texas and the Edwards plateau on prairies and other disturbed areas.
Native Habitat: Well-drained limestone, sand, caliche in open rangelands, pastures, poor areas.

Growing Conditions

Water Use: Low
Light Requirement: Sun
Soil Moisture: Dry
Drought Tolerance: High
Heat Tolerant: yes
Soil Description: Limestone-based, Sandy Sandy Loam, Medium Loam, Clay Loam Clay
Conditions Comments: Hairy tridens conforms to a short-grass prairie garden. It provides a good matrix in which to establish wildflowers. Winecup, four-nerve daisy, and blue-eyed grass combine well in plantings with hairy tridens because the grass provides an interesting contrast with its texture.


Use Ornamental: Attractive.
Use Wildlife: Seeds-granivorous birds; Small mammals-nesting material; Poor forage plant for livestock and wildlife.
Use Other: Some value in retarding soil erosion in dry regions subject to occasional heavy rains.
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: High


Propagation Material: Seeds
Seed Treatment: No special pre-treatment.
Commercially Avail: yes

From the National Organizations Directory

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

Fredericksburg Nature Center - Fredericksburg, TX
Lady Bird Johnson Wildflower Center - Austin, TX
Patsy Glenn Refuge, c/o Wimberley Birding Society - Wimberley, TX
Jacob's Well Natural Area - Wimberley, TX

Herbarium Specimen(s)

NPSOT 1056 Collected Aug 10, 1995 in Comal County by Mary Beth White
NPSOT 0951 Collected Sep 1, 1994 in Bexar County by Harry Cliffe

2 specimen(s) available in the Digital Herbarium

Wildflower Center Seed Bank

LBJWC-29 Collected 2006-05-16 in Travis County by Lady Bird Johnson Wildflower Center

1 collection(s) available in the Wildflower Center Seed Bank


Bibref 291 - Texas Wildscapes: Gardening for Wildlife (1999) Damude, N. & K.C. Bender

Search More Titles in Bibliography

Web Reference

Webref 3 - Flora of North America (2014) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.

Additional resources

USDA: Find Erioneuron pilosum in USDA Plants
FNA: Find Erioneuron pilosum in the Flora of North America (if available)
Google: Search Google for Erioneuron pilosum


Record Modified: 2021-09-18
Research By: TWC Staff

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