Plants 5-12(-20+) cm. Stems proximally piloso-hirsute (hairs 2-4+ mm) and stellate-pubescent, distally piloso-hirsute (hairs 1-4 mm), stellate-pubescent, and stipitate-glandular. Leaves: basal 8-12+, cauline 0(-2+); blades spatulate to oblanceolate, 20-45(-130+) × 8-20(-25+) mm, lengths 2-3+ times widths, bases cuneate, margins entire, apices rounded to acute, abaxial faces piloso-hirsute (hairs 1-4+ mm) and stellate-pubescent, adaxial piloso-hirsute (hairs 1-4+ mm). Heads 2-4+ in ± umbelliform to corymbiform arrays. Peduncles piloso-hirsute, stellate-pubescent, and stipitate-glandular. Calyculi: bractlets 13-15+. Involucres hemispheric, (9-)12-13 mm. Phyllaries 30-40, apices acuminate, abaxial faces stellate-pubescent, sometimes, piloso-hirsute and stipitate-glandular as well. Florets 90-120+; corollas yellow (often each with abaxial red stripe), 6-10+ mm. Cypselae columnar, 1-2.5 mm; pappi of 25-40+, white bristles in 1 series, 4-5+ mm. Flowering May. Disturbed sites, roadsides, forest edges; introduced; 10-300(-600+) m; B.C., N.B., N.S., P.E.I., Que.; Conn., Ind., Maine, Mass., Mich., N.H., N.Y., Ohio, Pa., Vt., Va.; Europe. The type of Hieracium flagellare may have resulted from a cross between plants of H. caespitosum and H. pilosella (A. Cronquist 1980).
