Common Boneset (Thoroughwort)

Eupatorium perfoliatum
Family

Asteraceae (daisies)

Description

A tall perennial with noticeable, spreading hairs. Flowerheads in flat-topped clusters with 9 to 23 florets in a head, dull white. Blooms July–October. Leaves to 8 inches long, triangular, tapering to a sharply pointed tip, finely toothed, opposite and perfoliate (opposite pairs with bases fused around the stem).

Similar species There are 11 Eupatorium species in Missouri. The most common ones can usually be separated by flower color (white or gray versus pale pink or pale purple) and by a combination of leaf characteristics.

Size

Height: usually 4, but sometimes up to 6 feet.

common_boneset_flower_clusters_8-31-15.jpg

Photo of common boneset plant flower clusters.
Common Boneset (Thoroughwort) Flower Clusters
The flowerheads of common boneset form flat-topped clusters with 9–23 dull white florets in a head. Blooms July–October.

common_boneset_leaves_8-31-15.jpg

Photo of common boneset plant showing leaves and stems.
Common Boneset (Thoroughwort) Leaves
The leaves of common boneset are hairy, narrowly triangular, and in opposite pairs fused around the stem.

common_boneset_flowers_8-31-15.jpg

Photo of common boneset plant closeup of flowers.
Common Boneset (Thoroughwort) Flowers
Like its relatives, common boneset has clusters of flowerheads that each bear a number of whitish disk florets, but no ray florets.

common_boneset_plant_8-31-15.jpg

Photo of common boneset plant in bloom.
Common Boneset (Thoroughwort)
Common boneset is scattered nearly statewide and generally occurs in moist situations.
Habitat and conservation

Generally occurs in moist situations: banks of streams and rivers, margins of ponds, lakes, and sinkhole ponds, bases and ledges of bluffs, fens, borders of sloughs, bottomland prairies, moist depressions of upland prairies, marshes, bottomland forests, and rarely openings of rich upland forests; also margins of fields and moist roadsides.

Distribution in Missouri

Scattered nearly statewide, but apparently absent from much of the western part of the Glaciated Plains of northwestern Missouri.

Human connections

Native Americans used eupatorium species to treat many ailments. Many say the fused, opposite leaves led to the notion that this plant could help heal and strengthen bones. Others say that pioneers called these plants “boneset” because they used them to treat fevers that made one’s bones ache.

Ecosystem connections

Many kinds of insects drink nectar from the flowers, and plants like this, that bloom late in the season, are crucial for insects that mature at that time. Because of the foliage’s bitterness, mammals don’t usually eat this plant. Thus it can become increasingly abundant in pastures.