Dogfennel (Identified as Weed, not True Grass)
Eupatorium capillifolium · Summer Perennial, C3 Dicot (Often mistaken for grass in vegetative state due to fine leaves)
Grass Family
Asteraceae (Sunflower family), not Poaceae (Grass family)
Grass Category
Invasive/Weed Grass (Non-graminoid weed)
Variety / Cultivar
None (Wild/Weed species)
Hardiness Zones
USDA Zones 3-10; dies back to the ground after a heavy frost and regrows from the woody crown in spring.
About This Grass
An upright, herbaceous perennial that grows 3-6 feet tall if unmowed. It has a feathery, fern-like appearance with finely dissected leaves and a strong, resinous odor when crushed. Stems are hairy and become woody at the base.
Blade Characteristics
Not true grass blades; leaves are finely dissected into thread-like segments, less than 1mm wide. Architecture is alternate/spiral, light to medium green, with no ligule or auricles.
Root System
Large, woody taproot with shallow lateral rhizomes; very difficult to pull by hand once established; low thatch, high drought tolerance.
Growing Information
Origin Region
Native to North America, primarily Southeastern United States; thrives in disturbed Soils and pastures.
Growth Habit
Clumping/Bunch-type from a woody base; spreads via wind-dispersed seeds and short rhizomes.
Sunlight & Water Needs
Full sun to partial shade; highly drought tolerant; thrives in poor, sandy, or disturbed acidic soils (pH 5.0-6.5).
Mowing & Maintenance
Not maintained as turf; in pastures/lawns, it requires frequent mowing to prevent woody stem development. Highly resistant to standard mowing due to basal regrowth.
Special Characteristics
Contains pyrrolizidine alkaloids (toxic to livestock); highly invasive in overgrazed pastures; notable for its scent and feathery texture.
Ecological Information
Native to US; provides cover for small mammals and is a host for certain moths (e.g., Euchaetes egle), but generally considered a nuisance weed in managed landscapes.