Helenium flexuosum aka Purplehead Sneezeweed

Helenium flexuosum is a perennial in the aster family. Common names include purple-headed sneezeweed and southern sneezeweed. Its native range covers eastern Canada and central and eastern America. It grows beside streams and in other wet places. These include swamps, damp meadows, and low spots in prairies. It also grows in pastures, old fields, and roadside ground. In disturbed sites, it can become weedy.

Plants form upright clumps with a medium growth rate. They reach 1–3 feet [0.30–0.91 metres] tall. Their spread is 1–2 feet [0.30–0.61 metres]. A single main stem branches near the top. The green stem has wings along its lower section. Dark green leaves grow in an alternate pattern. Each leaf is simple and shaped like a lance. The basal leaves reach about eight inches long. Upper leaves are smaller and have fewer teeth. The leaves bear hairs and small gland dots.

Flowers bloom from August to October and attract butterflies and other pollinators. Yellow rays droop around a rounded, dark purple-brown centre. Each ray ends in three lobes. The flower heads look like daisies with raised centres. Missouri Botanical Garden gives their width as about 1.5 inches. NC State lists a broader range of 1–3 inches. The dry fruits are achenes. NC State records fruit display from June through October. The flowers also suit cutting for indoor use.

Grow this plant in full sun and moist to wet soil. It prefers rich soil and does not tolerate dry ground. Clay, loam, and sand can all support it. It grows in USDA zones 5–9. Too much fertiliser can make the stems grow too tall. Cutting back in late spring or early summer encourages branching. Removing old flowers can bring more blooms. Divide clumps every three or four years to keep them vigorous. It suits borders, rain gardens, and pond or stream edges. Meadows and native gardens also provide suitable settings.

Deer and rabbits tend to leave this plant alone. Serious pest and disease problems are uncommon. Powdery mildew, leaf spot, and rust can affect the leaves. Flowers, leaves, and seeds are poisonous to people when eaten. Large amounts may cause vomiting, breathing trouble, and convulsions. NC State rates the poison risk as low. Historical uses included powders to trigger sneezing and leaf infusions as laxatives. Those records do not establish safe use as food or medicine.