This herbaceous perennial shrub blooms prolifically from July to October with white, slightly rounded flower clusters that are a crucial food source for a variety of insects.  It grows 2 to 5 feet tall and appears naturally in wetlands and other moist locations. It thrives when sited in moist, rich soils and full or part sun.  Common boneset tolerates sandy and clay soils as long as there is enough moisture retention, and it withstands temporary flooding.  It spreads easily in an upright, clumping form and often appears naturally with goldenrods, ironweeds, and other species that can be fairly aggressive.   
 
Common boneset is a member of the Eupatorium genus, which contains approximately 25 species of thoroughworts and bonesets.  The terms thoroughwort and boneset are often used interchangeably; for example, other names for common boneset include American boneset and American thoroughwort.  Many of the species look very similar, but common boneset is easily identified by its opposite, stalkless leaves that are fused together and “pierced” by the central stem (perfoliatum means “through the foliage”).  All Eupatoriums are hugely popular with late-season pollinators.   
 
Native habitats include moist locations, including marshes, wet fields, shores, thickets, and stream banks.  It’s used in wetland restorations and is ideal for rain gardens, wildflower gardens, edges of ponds, and other moist areas.   
 
Plant Characteristics: 
Grows 3-5’ tall. 
 
Prefers full sun or part shade. 
 
Prefers moist, rich soils but will grow in a variety of soils with some moisture. 
 
Clusters of flower heads are 2-8” wide; flower heads contain 9-23 florets.  Bloom period is between July and October. Small, dry achenes with hair-like bristles for wind dispersion appear September to November. 
 
Narrow, wrinkled leaves are 8” long, triangular, light or yellowish green, finely toothed, and tapered to a pointed tip. 
 
Central stem is unbranched and covered with long white hairs.  A few flowering side stems grow near the top of the plant. 
 
Wildlife Value: 
Host plant to 32 species of Lepidoptera larvae, including the moths clymene, way-lined emerald (both pictured here), red groundling and red-humped caterpillar. The nectar and pollen are collected by butterflies, bees, wasps, and pollinating flies.  Birds such as swamp sparrow eat the seeds.  Mammals usually avoid the bitter foliage. 
 
Medicinal, Edible, and Other Uses: 
Traditionally, boneset was grown in medical herb gardens and used to treat flu, fevers, colds, and other maladies. Native Americans used Eupatorium species to treat many ailments. Common boneset has also been used as a diaphoretic and anti-inflammatory. Some research suggests that the plant may act as a general immune system stimulant. 
 
It is thought that pioneers called the plant “boneset” because they used it to treat fevers that made one’s bones ache. 
 
All parts of the plant are bitter and have some toxicity.