Grass Category
Pasture Weed / Native Forb
Hardiness Zones
USDA Hardiness Zones 5 to 9
Grass Family
Asteraceae (Compositae), not technically a grass despite grassy-looking foliage
Variety / Cultivar
Wild type (No specific cultivars commonly designated)
About This Grass
An erect, branching summer annual plant with narrow, thread-like leaves and bright yellow, button-like composite flowers. Typically grows 6 to 24 inches tall. It has a strong bitter odor and taste when crushed, making it unpalatable to livestock.
Blade Characteristics
Leaves are alternate, simple, linear to thread-like (finely linear), entire or slightly toothed, light green to gray-green, glabrous, very narrow (less than 2mm wide), resembling grass blades at a distance.
Root System
Shallow, fibrous root system typical of annual weeds; establishes rapidly from seed in disturbed soils.
Growing Information
Origin Region
Native to North America (South-Central and Southeastern United States), common in pastures and disturbed soils
Growth Habit
Bunch-type (clump-forming annual forb with multiple erect branching stems)
Sunlight & Water Needs
Requires full sun and well-draining soils; highly drought tolerant once established; thrives in overgrazed or disturbed soils.
Mowing & Maintenance
High maintenance weed in pastures; hand pulling or herbicide application is recommended; mowing can prevent seed set if done before flowering.
Special Characteristics
Highly toxic to livestock if ingested in large quantities due to sesquiterpene lactones; taints milk with a bitter taste; highly invasive in overgrazed pastures.
Ecological Information
Native annual forb that acts as an indicator of overgrazing and poor pasture management. Provides little to no wildlife food value due to extreme bitterness, but flowers are visited by various generalist pollinators.