Eupatorium hyssopifolium aka Hyssop Leaf Thoroughwort

Eupatorium hyssopifolium is a perennial in the aster family. Its common names include hyssop-leaved boneset and hyssop-leaved thoroughwort. It comes from the eastern and central United States. Wild plants grow in dry woods, fields, and disturbed ground. They also occur in salt meadows and sandy or gravelly sites. This plant forms upright clumps and loses its leaves each year. Garden plants reach about 1–3 feet [0.3–0.9 metres] tall. RHS gives an upper height of 3.3 feet [1 metre]. Clumps spread 1–2 feet [0.3–0.6 metres], sometimes reaching 3.3 feet [1 metre].

The straight stems range from dark purple to brown. Fine hairs cover their surface. Narrow green or grey-green leaves give the plant a light texture. Leaves attach straight to the stems, without leaf stalks. They grow in rings of three or four. Most have smooth edges, though some have small teeth. The leaf edges may curl inward. These slim leaves help distinguish the plant among meadow flowers.

Small white flowers open from midsummer into autumn. Each head contains tubular disc flowers, with no ray florets. Dense, flat-topped clusters span about 0.4–0.8 feet [0.13–0.25 metres]. Bees and butterflies visit the flowers. The plant also hosts the Clymene moth. Its small, dry fruits are achenes with fine white hairs. Birds use the seed heads, which can remain through winter.

Grow this plant in sun or partial shade. Good drainage matters, but it accepts sand, loam, and clay. NC State favours dry, sandy soil and notes drought tolerance. RHS recommends moist soil that drains well. It accepts acid, neutral, and alkaline soils. Hardiness ratings cover USDA zones 4–8 and RHS H5. Growth is fast, and care needs are low. Divide clumps in spring, or sow seed in spring or autumn. Cut back the stems when the growing season ends.

Use it in meadows, wildlife beds, borders, or group plantings. It also suits dry slopes and gardens with native grasses. Deer, rabbits, salt, and urban conditions pose few problems. Aphids and slugs may attack, but serious disease is uncommon. Rhizomes and self-sown seed can extend a planting. Remove spent flowers to limit seedlings. No edible uses or known hazards are recorded by Plants For A Future. That does not establish that eating it is safe. The same source records external folk use for bites and stings. It also records use as a floor herb to deter insects.