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..
Serratula glauca L. Sp. Pl. 818. 1753.
Slender, glabrous or finely puberulent, 2°-5° high. Leaves thin, the lower broadly oval or slightly obovate, sharply serrate, acute or acuminate, 4'-7' long, 1'- 2 1/2' wide, the upper narrower and more finely toothed; inflorescence loosely branched; heads slender-peduncled, 10-20-flowered; involucre campanulate, 3"-4" broad; bracts ovate, with filiform tips, ap-pressed; achenes minutely hispidulous; pappus yellowish.
In woods, Pennsylvania and Maryland to Georgia and Alabama. Southern plants previously referred to this species prove to be distinct. Aug.-Sept.
Vernonia altissima var. marginata Torr. Ann.
Lyc. N. Y. 2: 210. 1827. Vernonia marginata Raf. Atl. Journ. 1: 146.
1832. Vernonia Jamesii T. & G. Fl. N. A. 2: 58. 1841. Cacalia marginata Kuntze, Rev. Gen. Pl. 968.
Glabrous or very nearly so, 1°-3° high. Leaves linear or linear-lanceolate, minutely denticulate, 1-nerved, firm, punctate, 2-5' long, 1 1/4"-3" wide, acuminate; inflorescence rather loose; heads slender-peduncled; involucre campanulate or turbinate, 15-30-flowered, 4"-6" broad; bracts ovate or oval, acute, mucro-nate or obtusish, purplish, somewhat pubescent, appressed; achenes nearly glabrous, or somewhat pubescent; pappus brownish.
Prairies, Nebraska and Kansas to Texas and New Mexico. Autumn.
Vernonia altissima Nutt. Gen. 2: 134. 1818. Vernonia maxima Small, Bull. Torr. Club 27: 280. 1900.
Glabrous or nearly so, 5°-10° high. Leaves thin, lanceolate, sometimes broadly so, usually long-acuminate, finely serrate, 4'-12' long, 1/2'-1 1/2' wide, glabrous on both surfaces, or puberulent beneath; inflorescence at length loosely branched and open; heads short-peduncled or some of them sessile; involucre campanulate or turbinate, 2"-3" broad, 15-30-flowered; bracts obtuse or mucronate, more or less ciliate, appressed; achenes slightly hispidulous; pappus purplish.
Vernonia fasciculata Michx.' Fl. Bor. Am. 2: 94. 1803.
Cacalia fasciculata Kuntze, Rev. Gen. Pl. 970. 1891.
Glabrous, or puberulent above, 2°-6° high. Leaves firm, lanceolate or linear-lanceolate, long-acuminate, 3'-6' long, 2"-4" wide, glabrous or nearly so on both surfaces; inflorescence usually compact; heads short-peduncled, or some of them sessile; involucre campanulate, 2"-3" broad, 20-30-flowered; bracts all appressed, ovate or oval, acute, ciliate, or sometimes pubescent; achenes glabrous, or a little pubescent; pappus purple.
In moist soil or on prairies, Ohio to Minnesota, Nebraska, Kansas and Oklahoma. Southern plants formerly referred to this species prove to be distinct. July-Sept.
Vernonia corymbosa Schwein., ranging from Manitoba to western Nebraska, has broader leaves but is otherwise similar.