Eupatorium hyssopifolium is a perennial herb, 30-140 cm tall, stems solitary, hairy, upper leaves with dense clusters of suppressed axillary branches.
Leaves in whorls of 3-4, almost stalkless, blades linear, 5-10 cm long, 0.5-1 cm wide, sprinkled with tiny translucent dots, margin entire.
Flowers dull white, 5 per head, bracteate base about 0.5 cm tall, cylindrical, finely gray-hairy; inflorescence rounded; blooms Aug.-Oct.
Fruit dry, 1-seeded, 5-angled plumed achene; wind dispersed; winter plant with persistent, star-shaped flower-head bases (receptacle), about 0.7 cm wide (M. Gargiullo personal observation). Seeds eaten by some birds (Martin et al. 1951).
Wetland status: UPL.
Frequency in NYC: Infrequent.
Habitat: Dry sand or soil, open areas.