Autumn sneezeweed is a late-blooming perennial with conspicuously winged stems. The flowerheads have yellow, domed disks. The ray flowers are fan-shaped, yellow, and notched.
Autumn sneezeweed is a perennial wildflower with branching, winged stems.
The flowerheads are many, all yellow, with 10–18 ray that are florets fan-shaped, notched, and reflexed downward. The large disk (receptacle) is dome-shaped.
Blooms August–November.
The leaves are alternate, well-developed along the stem, with the basal and lower stem leaves usually somewhat smaller than the median ones and absent at flowering time; usually oblanceolate to elliptic to lance-shaped, entire or with teeth (often above the midpoint); the leaf tissue extending down the stem as wings.
Similar species: Three other heleniums grow in Missouri:
Bitterweed is an annual, has profuse, linear (grasslike) leaves, and lacks wings of leafy tissue on the stems.
Purple-headed sneezeweed is Missouri's only sneezeweed with purple or brownish (not yellow) disk florets.
Virginia sneezeweed is the rarest of Missouri's sneezeweeds, occurring only in the south-central Ozarks. It's the species most similar to autumn sneezeweed, and a species of conservation concern.
- It lives in wetter soils and blooms earlier (July–September).
- Its leaves are distinctive: alternate or mostly basal, with the basal and lower stem leaves to 7 inches long, significantly larger than the middle and upper stem leaves (which are only to about 5 inches long and are smaller and smaller up the stem); the basal and lower leaves are usually persistent at flowering time and are wider toward the outer tip, and unlobed or with shallow, rounded lobes.
Height: to 6 feet.
Scattered nearly statewide except Southeast Lowlands and the northwestern section of the state.
Habitat and Conservation
Occurs on banks of streams, rivers, and spring branches, margins of ponds, lakes, and sinkhole ponds, sloughs, fens, and seeps, marshes, bottomland prairies, moist depressions of upland prairies, and bottomland forests; also pastures, ditches, railroads, roadsides, and moist, open, disturbed areas.
Status
Native Missouri wildflower.
Human Connections
Sneezeweeds were used historically by Native Americans and pioneers as snuff. Inhaling the dried, powdered disk florets caused violent, prolonged sneezing, and people did this as a way of alleviating colds, stuffy noses, headache, and other maladies.
Ecosystem Connections
Numerous bees, wasps, flies, butterflies, and beetles visit the flowers for nectar and pollen.
Aphids suck the sap, and moth caterpillars bore in the stems.
Sneezeweeds contain toxic, bitter substances, and grazing mammals, including cattle, avoid eating them.
Autumn sneezeweed was part of a decades-long botanical mystery. Collections made by Julian Steyermark in Howell County in 1960 of unusual but similar plants were long thought to be oddball hybrids of autumn sneezeweed and purple-headed sneezeweed.
- But in 2000, DNA testing proved they were not descendants of those species; instead, they were Virginia sneezeweed, until then known only as an endangered plant growing along sinkhole ponds in the Shenandoah Valley of Virginia.
- Population research and conservation efforts since then seem to be helping to increase the survival chances for that species.
