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..
Helianthus subrhomboideus Rydb. Mem. N. Y. Bot. Gard. 1: 419. 1900.
Stem simple, sparingly hirsute, usually tinged with red. Leaves opposite, firm, very scabrous, 3-nerved, slightly serrate, the basal ones broadly ovate to obovate-spatulate, those of the stem rhomboid-ov.ate to rhomboid-lanceolate, short-petioled, 2'- 4' long, the uppermost very small; heads 1-3, 1'- 3/4 in diameter; bracts of the involucre oblong, acutish, densely white-ciliate; disk purple.
Plains, Manitoba and Saskatchewan to South Dakota, Nebraska, Montana and New Mexico. Adventive, New Jersey to New Hampshire. July-Sept. Included in H. scaberrimus in our first edition.
Perennial; stems appressed-pubescent or sometimes nearly glabrous, slender, mostly simple, 1°-3° high. Leaves mostly basal, or below the middle of the stem, firm, ovate or oblong-lanceolate, obtuse or obtusish at the apex, narrowed at the base, 3-5-nerved, serrulate or entire, scabrous above, pubescent beneath, with slender petioles about as long as the blades; stem usually bearing 1 or 2 pairs of small distant leaves; heads several or solitary, 1 1/2' - 2 1/2' broad; involucre hemispheric, its bracts lanceolate or ovate-lanceolate, acute or acuminate, generally ciliate, appressed; receptacle convex, its chaff acute; disk yellow; rays 12-15; achenes truncate and pubescent at the summit; pappus of 2 lanceolate-subulate awns. In dry soil, Ohio to Minnesota, south to Florida and Missouri. Aug.-Sept. Helianthus Dowellianus M. A. Curtis, which differs in being stouter, the stem leafy, the leaves merely puberulent, and ranges from the District of Columbia to Georgia, appears to be a race of this species.
Helianthus laevigatus T. & G. Fl. N. A. 2: 330. 1842.
Stems slender, from a perennial root, simple or little branched, glabrous, or somewhat glaucous, 2°- 6° high. Leaves nearly all opposite, firm, glabrous, lanceolate, short-petioled, or the upper sessile, serrulate or entire, pale beneath, acuminate, nar-nowed at the base, 3'- 6' long, 1/2' - 1 1/2' wide, the margins sometimes roughish-ciliate; heads few or solitary, 1' - 1 1/2' broad; involucre campanulate, its bracts lanceolate or ovate-lanceolate, firm, ciliolate, the tips of the outer ones spreading; rays 5-10; disk yellow; chaff linear; achenes slightly pubescent at the summit; pappus of 2 lanceolate or ovate owns, with or without 2 intermediate scales.
In dry soil, mountains of Virginia, West Virginia and North Carolina. Aug.-Oct.