Fl. Bor.-Amer. 1: 298. 1833.
Plants 30–75(–200) cm. Stems proximally piloso-hirsute (hairs 6–15+ mm), distally piloso-hirsute (hairs 3–10+ mm), sometimes stellate-pubescent as well. Leaves: basal 3–8+, cauline (3–)6–12+; blades oblanceolate, 45–80(–250+) × 12–30(–40+) mm, lengths 4–7+ times widths, bases cuneate, margins entire, apices rounded to acute, faces piloso-hirsute (hairs 3–8+ mm). Heads 10–20+ in paniculiform to nearly racemiform arrays. Peduncles stellate-pubescent and stipitate-glandular, sometimes piloso-hirsute as well. Calyculi: bractlets 9–13+. Involucres campanulate, 6–8(–10) mm. Phyllaries 12–21+, apices acuminate, abaxial faces stellate-pubescent and stipitate-glandular. Florets 30–40(–60); corollas yellow, ca. 7 mm. Cypselae urceolate, 3–4+ mm; pappi of 35–40+, stramineous to sordid bristles in 2+ series, 5.5–6.5 mm.
Phenology: Flowering Jul–Sep.
Habitat: Fields, prairies, roadsides
Elevation: 100–400 m
Ont., Ark., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Mo., Nebr., Ohio, Okla., Tenn., Tex., Wis.
Hieracium longipilum may be no longer present in Quebec.