Purple-headed sneezeweed is a perennial wildflower with branching, winged stems. The flowerheads are many, with 8–13 yellow ray florets that are fan-shaped, notched, and reflexed downward. The large disk is brownish or purplish and dome-shaped to nearly spherical. Blooms June–November. Leaves, at flowering time, are mostly on the middle parts of the stem, having withered away on the lower parts; leaves are alternate, narrowly lance-shaped, with or without a few teeth; the leaf tissue extending down the stem as wings.
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 has purplish or brownish disk florets.
Height: 8 inches to nearly 4 feet.
Scattered, mostly south of the Missouri River.
Habitat and Conservation
Occurs on banks of streams, rivers, and spring branches, margins of sinkhole ponds, sloughs, swamps, bottomland prairies, moist depressions of upland prairies, bottomland forests, and seepy ledges of bluffs; also pastures, old fields, ditches, railroads, roadsides, and moist, open, disturbed areas.
Native Missouri wildflower.
Missouri has more than 320 aster-family species, and this is the only one with its unique combination of traits — domed, purple head; winged stems; fan-shaped yellow ray flowers — isn’t it amazing that we can learn to know each plant, kind of how we get to know our friends?
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.
Collections in Howell County in 1960 of unusual but similar plants were long considered hybrids of autumn sneezeweed and purple-headed sneezeweed. But in 2000 DNA testing proved they were not descendants of those species, and showed they were instead a different species, the federally threatened and state endangered Virginia sneezeweed. Population research and conservation efforts since then seem to be helping to increase the survival chances for that species.