Dog Fennel
Eupatorium capillifolium
Dog fennel is a tall, feathery-leaved native weed of the southeastern United States that forms dense stands in old fields and roadsides and has an aromatic, somewhat unpleasant scent.
- Light
- Full sun
- Water
- Low to moderate; drought-tolerant
- Difficulty
- Easy
Got a plant like this?
Identify any plant from a photo, free.
Overview
Dog fennel (Eupatorium capillifolium) is a tall perennial wildflower in the aster family, native to the southeastern and eastern United States. Its finely dissected, fern-like foliage gives it a soft, feathery, almost cypress-like look, earning names like 'cypressweed.'
It is a familiar colonizer of old fields, pastures and roadsides, where it can form dense stands several meters tall by late summer. Aromatic but ill-scented, it is generally regarded as a weed.
How to identify it
A tall, much-branched perennial reaching 1–3 m (3–10 ft) by season's end.
- Leaves: finely divided into thread-like (capillary) segments, giving a feathery, fern- or dill-like appearance
- Stems: erect, multiple, often hairy, branching toward the top
- Flowers: numerous tiny, dull greenish-white heads in branched sprays in late summer and fall
- Odor: aromatic when crushed, with a scent many find unpleasant
Care & growing
Not cultivated; managed as a pasture and field weed.
- Light: full sun
- Water: drought-tolerant; tolerates a range of moisture
- Soil: thrives on poor, sandy, disturbed and abandoned ground
- Temperature: warm-season perennial, dying back in winter and regrowing from the crown
- Propagation: by abundant wind-borne seed and from the perennial root crown
Control by mowing before seed set, maintaining vigorous pasture, and using herbicides on heavy infestations.
Habitat & origin
Native to the southeastern and eastern United States, dog fennel is widespread across the Coastal Plain and beyond. It colonizes old fields, overgrazed pastures, roadsides, fence lines and other disturbed, poor soils.
It is one of the most conspicuous weeds of abandoned agricultural land in the South, often forming pure stands.
Frequently asked questions
Is dog fennel the same as the herb fennel?
No. Culinary fennel is Foeniculum vulgare; dog fennel (Eupatorium capillifolium) is an unrelated aster-family weed that merely has similarly feathery leaves.
How do I control dog fennel in a pasture?
Mow before it sets seed, keep grass competitive and well-managed, and spot-treat dense stands with appropriate herbicides.
Why is it called dog fennel?
The name reflects its feathery fennel-like foliage combined with its rank, unpleasant smell — a 'false' or worthless fennel.
How tall does dog fennel grow?
By the end of the season it can reach 1–3 m (3–10 ft) tall, forming dense, much-branched stands topped with sprays of tiny greenish-white flower heads.
Dog Fennel guides
In-depth guides for identifying, growing, and caring for Dog Fennel.
