Eupatorium capillifolium, or dog fennel (also written "dogfennel"), is a North American perennial herbaceous plant in the family Asteraceae, native to the eastern and south-central United States.

[7][8] Dog fennel thrives on roadsides,[6] in fields and reduced tillage crops, as well as areas that have burned or otherwise been disturbed.

It is native to the southern and eastern United States, from Massachusetts south to Florida, and west to Missouri and Texas,[9][10] and also Cuba and the Bahamas.

[11] Dog fennel is eaten by Florida's scarlet-bodied wasp moth, Cosmosoma myrodora.

[12] Dog fennel contains liver-damaging pyrrolizidine alkaloids, so livestock are known to eat all the turf around a stand of it.