Eupatorium rotundifolium aka Roundleaf Thoroughwort

Eupatorium rotundifolium is a perennial wildflower in the aster family, Asteraceae. Its common names include roundleaf thoroughwort and false horehound. It comes from the central and eastern United States, including North Carolina. In the wild, it grows in woods, savannas, and bogs. This range of habitats reflects its tolerance of wet and dry soil.

The plant grows upright and reaches about 3 feet [0.9 metres]. Some plants grow taller, though the source gives no upper limit. It dies back to ground level in winter. Rounded leaf rosettes emerge again in spring. A short rhizome sends up a single, straight stem. This stem may branch near the top as it grows. The stems bear hairs and may be green or cream to tan. They have no scent.

The simple leaves range from green to gray-green. Most grow in opposite pairs, though some grow alternately. They lack leaf stalks and have low, rounded teeth. Leaf shapes range from rounded to egg-shaped or triangular. Three strong veins spread from the base of each leaf. Leaves measure about 0.08–0.25 feet [0.025–0.076 metres] long. Their shape and stalkless attachment help identify this species.

White flower heads appear in summer and fall. Each small head holds five disk florets. The heads form an umbel up to 0.5 feet [0.15 metres] across. These flower clusters stand near the tops of the stems. Native bees and butterflies visit the flowers in large numbers. The fruit is an achene, and birds eat the seeds. Its flowers and seeds give it value in wildlife gardens.

Grow roundleaf thoroughwort in full sun or partial shade. It suits sandy soil with a near-neutral pH. Moist soil suits it, but it also tolerates brief wet or dry spells. Long droughts can scorch the leaves, despite its tolerance of dry soil. It grows fast and is hardy in USDA zones 4–8. The source lists medium maintenance and recommends raising plants from seed. Use it in groups in meadows, woodland plantings, and native gardens. It also fits rain gardens and plantings made for pollinators. Deer and rabbits tend to leave it alone. No serious insect or disease problems are reported.