Helianthus decapetalus is a perennial herb, colonial from rhizomes, stem 0.5-1.5 m tall, smooth below hairy inflorescence.
Leaves opposite below, usually alternate above (in inflorescence), stalk 2-6 cm long, blade 8-20 cm long, 3-8 cm wide, tip long-pointed, base abruptly narrowed, extending down stalk, thin, pale below, somewhat rough textured, margin sharply toothed, 3-veined at base.
Flower head about 4 cm wide, rays yellow, 8-15, 2 cm long, not fertile, disk yellow 1-2 cm wide, basal bracts loose, often curled back, tips long-pointed and often longer than disk, margins hairy; blooms and fruits Aug.-Oct.
Fruit dry, 1seeded achene, crowned by deciduous scales, surrounded by chaffy bracts of the floral base. Seeds eaten by numerous birds and small mammals (Martin et al. 1951).
Wetland status: FACU.
Frequency in NYC: Infrequent. May be locally common.
Habitat: Upland woods.
Note: May closely resemble Verbesina alternifolia.