Prosp. Hist. Pl. Dauphiné, 34. 1779.
Plants 15–40(–70+) cm. Stems proximally usually piloso-hirsute (hairs 2–4+ mm), rarely glabrous, distally usually glabrous, sometimes piloso-hirsute (hairs 1–3+ mm), stellate-pubescent, and/or stipitate-glandular. Leaves: basal 3–8(–20+), cauline 0–2(–4+); blades oblanceolate to lanceolate, 30–100(–150+) × 8–20+ mm, lengths 2.5–8+ times widths, bases cuneate, margins entire or denticulate, apices rounded to acute, faces glabrous or piloso-hirsute (on midribs and at margins, hairs 1–4+ mm). Heads (3–)10–30+ in subumbelliform or corymbiform arrays. Peduncles piloso-hirsute (hairs 1–2+ mm), stellate-pubescent, and stipitate-glandular. Calyculi: bractlets 3–12+. Involucres campanulate, 5–7 mm. Phyllaries 12–18+, apices acute to acuminate, abaxial faces piloso-hirsute (hairs 0.5–1.5+), stellate-pubescent, and stipitate-glandular. Florets (40–)60–80+; corollas yellow, 6–9 mm. Cypselae columnar, 1.5–2 mm; pappi of 25–40+,white bristles in 1 series, 3–4 mm.
Phenology: Flowering (May–)Jun–Aug(–Sep).
Habitat: Disturbed sites
Elevation: 10–300(–1500) m
Introduced; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Conn., Del., Ga., Ill., Ind., Iowa, Maine, Md., Mass., Mich., Minn., Mont., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Vt., Va., Wash., W.Va., Wis., Europe.
Plants called Hieracium praealtum Villars ex Gochnat (at least those called H. praealtum var. decipiens W. D. J. Koch) reputedly differ from members of H. piloselloides in having blades of their proximal leaves stellate-pubescent abaxially (M. L. Fernald 1950); such plants may be found in the flora and may merit taxonomic recognition.