Vernonia noveboracensis (L.) Willd.

Plants 8–12(–20) dm. Stems puberulent, glabrescent. Leaves mostly cauline; blades ± lanceolate, 9–15(–25+) cm × 15–45(–60+) mm, l/w = (3.3–)4–6+, abaxially scabrellous, tomentose, or pannose, resin-gland-dotted, adaxially scabrellous, often resin-gland-dotted. Heads in corymbiform to paniculiform arrays. Peduncles 2–35 mm. Involucres ± hemispheric, 6–10 × 7–10 mm. Phyllaries 35–60+ in 4–6+ series, sparsely tomentulose, glabrescent, margins ciliolate, the outer lanceolate to subulate, 1–3 mm, inner oblong, 7–9+ mm, tips subulate to filiform. Florets 30–45(–65). Cypselae 3.5–4+ mm; pappi fuscous to purplish, outer scales 20, 0.2–0.6+ mm, contrasting with 30–40+, 5–7+ mm inner bristles. 2n = 34.

Serratula noveboracensis Linnaeus, Sp. Pl. 2: 818. 1753; Vernonia harperi Gleason; V. noveboracensis var. tomentosa Britton