This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Hieracium murorum L. Sp. Pl. 802. 1753.
Stem pubescent or glabrate, simple, or with 1 or 2 branches, 1°-2 1/2° high. Basal leaves thin, ovate or oblong, obtuse or acute, cordate or truncate at the base, or abruptly narrowed into petioles, coarsely dentate or laciniate, at least near the base, 2'-4 long, 1'-2' wide, the petioles villous; stem leaves 1 or 2, short-petioled or sessile, sometimes none; heads 2-several, corymbose, about 1' broad; peduncles ascending, usually glandular; involucre 4"-5" high, its bracts linear-lanceolate, acute, glandular-pubescent, imbricated in 2 or 3 series; achenes columnar, truncate; pappus of slender nearly white bristles.
Woodlands near Brooklyn, N. Y., Northampton, Mass., and about Quebec. Adventive or fugitive from Europe. French or golden lungwort. June-Aug.
Similar to the preceding species, sometimes taller and slightly glaucous; stem 2-5-leaved, pubescent or glabrate. Basal leaves oblong or lanceolate, acute at both ends, or some of them obtuse at the apex, coarsely dentate or denticulate, petioled, 2'-5' long, 1/2'-1 1/2' wide, often mottled; stem leaves similar, short-petioled or sessile; petioles more or less pubescent; heads several, corymbose, smaller than those of H. murorum or as large; peduncles mostly glandular, straight; bracts of the involucre imbricated in 2 or 3 series, linear, acuminate, mostly glandular; achenes columnar, truncate; pappus copious.
Labrador and Newfoundland to Quebec, and in southern New York and New Jersey. Naturalized from Europe. Also in Greenland, northern Europe and Asia. July-Sept.
H. canadense Michx. Fl. Bor. Am. 2: 86. 1803.
Stem erect, firm, glabrate or pubescent, leafy, 1°-5° high. Leaves numerous, ovate, oblong-lanceolate, ovate-oblong, or lanceolate, acute or acuminate at the apex, rounded, sessile, and, at least the upper ones, clasping at the base, 1-3' long, 3"-12" wide, serrate or incised, the margins sometimes ciliolate, glabrous or pubescent beneath, the lowest somewhat spatulate and petioled; no tuft of basal leaves at flowering time; heads usually numerous, corymbose-paniculate, about 1' broad; involucre about 6" high, pubescent or puberulent, its bracts imbricated in 2-3 series, the outer spreading; flowers yellow; achenes columnar, truncate; pappus copious, brown.