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. Flowering Jul-Sep. Fields, prairies, roadsides; 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.
From Flora of Indiana (1940) by Charles C. Deam
This species has been reported from the dune area, Lower Wabash Valley, and from Parke, St. Joseph, Steuben, and Vigo Counties. I have seen the Parke County specimen and it should be referred to Hieracium Gronovii. This hawkweed is a weed in sandy fallow fields in the vicinity of Heaton Lake, Elkhart County, and in several fields in northeastern St. Joseph County. It is probably more widely distributed. I noted it as frequent in the old Beaver Lake Basin about 3 miles south of Lake Village, Newton County.
Plant with a short stout caudex or crown; stem 6-20 dm, densely long-hairy below, the hairs mostly 1 cm or more, sometimes 2 cm, becoming glabrous or nearly so above; lvs pubescent like the stem, or the hairs shorter; basal and lower cauline lvs rather numerous, oblanceolate or narrowly elliptic, 9-30 נ1.5-4.5 cm, crowded, the lowest ones often deciduous, the others progressively reduced upwards, the upper half of the stem commonly naked or merely bracteate; infl elongate, cylindric, the branches and peduncles stellate, long-stipitate-glandular and sometimes sparsely setose; invol 7-10 mm, stellate-puberulent and hispid with blackish, mostly gland-tipped hairs; fls 40-90; achenes 3-4.5 mm, narrowed above. Dry prairies, open woods, and fields, especially in sandy soil; Mich. and Ind. to Minn., Kans., and Okla. July, Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.