Bitterweed (Bitter Sneezeweed)

Photo of blooming bitterweed plant shown from top.
Scientific Name
Helenium amarum
Asteraceae (daisies, sunflowers)

Much-branched annual. Flowerheads few to many on naked stems above the foliage, yellow, the 5–10 ray florets reflexed and notched; the disk bowl-shaped, pointing skyward, yellow. Blooms June–October. Leaves profuse, linear (very narrow), to 1½ inches long with smaller leaves arising from axils of larger ones. Plant contains bitter, toxic substances, and cattle forced to graze on it in overgrazed pastures produce bitter milk, thus the name bitterweed.

Similar species: Four species of Helenium grow in Missouri. The others are discussed elsewhere in this guide. All have rounded disks and yellow, fan-shaped, drooping ray flowers. This is the only one that is annual, has profuse, linear leaves, and lacks wings of leafy tissue on the stems.

Other Common Names
Yellow Dog-Fennel

Height: usually to 1 foot, but rarely to 2 feet.

Where To Find
image of Bitterweed Bitter Sneezeweed Yellow Dog Fennel Distribution Map

Scattered to common, mostly south of the Missouri River.

Occurs on banks of streams and rivers, openings of dry upland forests, and disturbed portions of upland prairies; also pastures, farmyards, railroads, roadsides, and open, disturbed areas. It forms dense populations along mowed roadsides and in overgrazed pastures. The weediest sneezeweed in Missouri, bitterweed’s home range is in Texas and Louisiana. It was first collected in our state in about 1879, and over the next 20 years it increased its range rapidly.

The dried and powdered flowers were historically used as snuff. Sneezeweeds contain toxic, bitter substances. In the West, they cause “spewing disease” in cattle, with vomiting, diarrhea, and death. Grazing animals avoid these plants. Pastures full of sneezeweeds have probably been overgrazed.

Bees, wasps, butterflies, beetles, and other insects collect nectar and pollen from the flowers. The larvae of some moths bore into the stems and roots, and weevil larvae bore into the immature seeds. Prairie-chicken are known to eat the seedheads. Most mammals avoid eating the bitter foliage.

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Similar Species
About Wildflowers, Grasses and Other Nonwoody Plants in Missouri
A very simple way of thinking about the green world is to divide the vascular plants into two groups: woody and nonwoody (or herbaceous). But this is an artificial division; many plant families include some species that are woody and some that are not. The diversity of nonwoody vascular plants is staggering! Think of all the ferns, grasses, sedges, lilies, peas, sunflowers, nightshades, milkweeds, mustards, mints, and mallows — weeds and wildflowers — and many more!