Horseweed (marestail)
Erigeron canadensis · Warm-season, annual broadleaf weed, C3/C4 intermediate
AI-generated identification · may be incorrect
Grass Category
Invasive/Weed Grass or Agricultural Weed
Hardiness Zones
USDA Hardiness Zones 2 to 10
Grass Family
Asteraceae (Note: This plant is actually a broadleaf weed in the daisy family, not a true grass, though commonly found in similar habitats)
Variety / Cultivar
Wild type
About This Grass
An upright, single-stemmed annual weed that can grow from 1 to 6 feet tall. It features numerous small, crowded, linear to lance-shaped leaves and produces a large, branching panicle of small flower heads with white or pinkish ray florets and yellow disk florets that turn fuzzy and brown at maturity.
Blade Characteristics
Leaves are alternate, simple, narrow, lance-shaped, 1 to 4 inches long, with entire or slightly toothed margins, hairy surfaces, and no true grass ligules or auricles
Root System
Taproot system with fibrous lateral roots; establishes quickly in disturbed soils
Growing Information
Origin Region
Native to North America, now widespread globally in temperate and subtropical regions
Growth Habit
Erect, unbranched stem initially forming a low rosette of leaves before bolting upright
Sunlight & Water Needs
Requires full sun; highly adaptable to varying moisture levels with good drought tolerance once established; thrives in well-drained disturbed soils
Mowing & Maintenance
Controlled primarily by mowing, pulling, or broadleaf herbicides; cannot survive frequent close mowing
Special Characteristics
High seed production, wind-dispersed seeds, known for developing resistance to glyphosate and other common herbicides, highly competitive in no-till systems
Ecological Information
Pioneer species in disturbed areas, abandoned fields, and crop lands; provides minimal wildlife value compared to native grasses; often considered a troublesome agricultural weed