Students for Stewardship The Cork Board
← Back to the library

Grease Grass

Tridens flavus (TRY-dens FLA-vus)

Family: Poaceae Native Herbaceous (3-15 ft)

A native ornamental warm-season bunchgrass in the Poaceae family. It has attractive reddish-purple seed heads that appear in the late summer and persist into fall and are especially impactful when planted en masse. It is a salt-tolerant grass and is often seen growing along roadside ditches. Its seed heads are oily, hence the common name grease grass, and are a food source for birds and mammals. Purple Top is a perennial warm-season grass that grows 3-5 feet tall and 3 feet wide. It has a rich hue to its foliage as it develops each spring. Shortly after the foliage matures, the flower spikes develop as purple panicles that bloom from August to November. Deer resistance is high. This is a larval host plant that supports various skipper larvae and the Common Wood-Nymph ( Cercyonis pegala ) which has one brood from late May to October. Adult Common Wood-Nymph butterflies feed on rotting plant matter. This species is also the larval host of a number of butterflies and moths, including Polites origenes (Crossline Skipper), Pompeius verna (Little Glassywing), and Poanes viator (Broad-winged Skipper). The plant provides excellent cover year-round. Seasons of Interest: Bloom: Summer-Fall, August-October; Fruit/Seed/Nut: Fall/Winter Insects, Diseases, or Other Plant Problems:

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 49 attributes.

How it fits the guild

Guild layer 4 - Herbaceous (3-15 ft)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Full plant profile

Growing Conditions
Plant type
Native Plant; Ornamental Grasses and Sedges; Perennial
Life cycle
Perennial
USDA zones
4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Light
Dappled Sunlight (Shade through upper canopy all day) | Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; High Organic Matter; Loam (Silt); Sand; Shallow Rocky
Soil drainage
Good Drainage | Moist | Occasionally Dry
Available space
12 inches-3 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 3 ft. 0 in. - 5 ft. 0 in. | Width: 1 ft. 0 in. - 3 ft. 0 in.
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Clumping; Erect
Texture
Coarse
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Linear
Leaf margin
Entire
Leaf feel
Rough
Leaf size
> 6 inches long, < 1 inch wide
Hairs present
Yes
Leaf detail
Linear green leaves are shallowly grooved to flat and up to 16 inches long and 10 mm wide. Leaves tightly sheath the stem.
Flower color
Brown/Copper; Cream/Tan; Gold/Yellow; Purple/Lavender
Flower value
Good Cut; Long-lasting; Showy
Flower form
Panicle
Flower detail
Purple panicles of spikelets appear July to October.
Bloom time
Fall; Summer
Fruit type
Caryopsis
Fruit detail
Fruits display from September to November.
Wildlife & Ecology
Native status
Native
Origin
North America, NC
Distribution
AL , AR , CT , DC , DE , FL , GA , IA , IL , IN , KS , KY , LA , MA , MD , MI , MN , MO , MS , NC , NE , NH , NJ , NM , NY , OH , OK , PA , RI , SC , TN , TX , VA , VT , WI , WV
Wildlife value
Seed heads are a food source for birds and mammals. This is a larval host plant that supports various skipper larvae and Common Wood-Nymph (Cercyonis pegala) which have one brood from late May to October. Adult Common Wood-Nymph butterflies feed on rotting plant matter. This species is also the larval host of a number of butterflies and moths, including Polites origenes (Crossline Skipper), Pompeius verna (Little Glassywing), and Poanes viator (Broad-winged Skipper). It provides excellent cover year-round.
Attracts
Butterflies; Moths; Songbirds
Host plant for
a number of butterflies and moths, including Polites origenes (Crossline Skipper), Pompeius verna (Little Glassywing), and Poanes viator (Broad-winged Skipper)
Food & Medicine
Harvest time
Fall
Fruit type
Caryopsis
Landscape Use
Landscape location
Meadow; Naturalized Area; Woodland
Landscape theme
Native Garden; Winter Garden
Garden tags
#purple #salt tolerant #moth caterpillar host #deer resistant #native garden #larval host plant #NC native #native ornamental grass #bird friendly #butterfly friendly #Piedmont Mountains FACU #food source herbage #food source hard mast fruit #Coastal FACU #mammals #food source fall #Audubon #common wood-nymph butterfly #perennial #wildlife friendly #skipper butterflies #pollinator plant #NC Native Pollinator Plant #winter cover
Problems & Resistance
Resistant to
Deer; Salt
Particularly resistant to
Salt, Deer, Drought, Erosion, Dry Soil, Air Pollution
Propagation
Division; Seed

Planted at Hunnicutt

Nobody’s planted this one yet.