Plants ca. 65 cm. Stems proximally piloso-hirsute (hairs 2-3+ mm), distally glabrous or stellate-pubescent, sometimes piloso-hirsute as well (hairs 1-2 mm). Leaves: basal 0, cauline 12-20+; blades ± lanceolate, 30-80 × 10-25 mm, lengths 2-4+ times widths, bases cuneate, margins usually toothed, apices acute to acuminate, abaxial faces piloso-hirsute, adaxial glabrous or ± scabrellous (especially distal margins). Heads 25-30+ in corymbiform arrays. Peduncles stellate-pubescent. Calyculi: bractlets 21+. Involucres campanulate, 8-9 mm. Phyllaries 21+, apices ± rounded, abaxial faces stellate-pubescent and stipitate-glandular. Florets 40-60+; corollas yellow, ca. 10 mm. Cypselae columnar, 2.5-3 mm; pappi of ca. 60+, stramineous bristles in ± 2 series, ca. 6 mm. Flowering Aug-Sep. Disturbed sites (grasslands, open woods); introduced; 10+ m; B.C., N.S.; Conn., Maine, Mass., N.J., N.Y., Pa., Wis.; Europe.
Similar to no. 12 [Hieracium kalmii L.], the lvs avg a little larger; lower part of the stem and lower surfaces of the lvs sparsely to densely provided with long, firm, bulbous-based hairs, not at all stellate, the upper surface of the lvs similarly hairy or more often glabrous; infl generally narrow, the lower branches and peduncles elongate but closely ascending; 2n=18, 27. Native of Europe; established as a weed from Mass. to Pa. Aug.-Oct.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.