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..
Taller, sometimes 9° high, glabrous or nearly so, or crisp-pubescent above. Leaves pinnately 3-5-divided, the veins straight and prominent; heads larger, 7"-12" broad, stout-peduncled; outer invo-lucral bracts linear to linear-spatulate, ciliate, the inner mostly ovate or narrowly triangular, pubescent at apex; ray-flowers usually present, small, yellow; achenes very flat, 3"-41/2" long, 2"-2 1/2" wide, brown or greenish brown, the margins downwardly barbed above, upwardly hairy below; awns 2, half as long as the achene or more, downwardly barbed.
In moist soil, Quebec to British Columbia, New York, North Carolina, Missouri, Colorado and California. Aug.-Sept. Included in the preceding species in our first edition.
Didens bipinnata L. Sp. Pl. 832. 1753.
Annual; stem quadrangular, erect, freely branched, rather slender, 1°-5° high. Leaves thin, acuminate, petioled, 1-3-pinnately dissected into ovate or oblong, toothed or lobed segments, the lower often 8' long; heads usually numerous, long-peduncled, 2"-4" broad; involucre narrow, its outer bracts linear, ascending, nearly as long as the broader erect inner ones; rays 3-4, yellow, short, sometimes none; achenes linear, 4-angled, slightly pubescent, narrowed upward into a beak, 5"-9' long, the outer ones commonly shorter and thicker than the inner; pappus of 2-4 (usually 4), downwardly barbed, slightly unequal, spreading awns, much shorter than the achene.
In various situations, often a weed in cultivated fields, Rhode Island to Florida, Ohio, Nebraska, Kansas and Arizona. Introduced as a weed into southern Europe and Asia. July-Oct.
Coreopsis coronata L. Sp. Pl. Ed. 2, 1281. 1763.
Coreopsis aurea Ait. Hort. Kew. 3: 252. 1789.
Bidens coronata Fisch.; Steudel, Nom. Ed. 2, 202. 1840.
Annual, glabrous or nearly so throughout; stem branched, 1°-3° high. Lower leaves petioled, 3-5' long, 3-divided, the terminal segment lanceolate, acute or acuminate, serrate, much larger than the serrate or entire lateral ones; upper leaves much smaller, 3-parted, 3-lobed or undivided, sessile or short-petioled, entire or serrate; leaves rarely all undivided; heads numerous, slender-peduncled, 1'-2' broad; involucre hemispheric, its outer bracts linear-oblong, obtuse, equalling or slightly exceeding the broader inner ones; rays 6-10, obtuse; achenes broadly cuneate, slightly pubescent, 1"-2" long; pappus of 2 chaffy blunt divergent somewhat laciniate teeth, rarely with 2 shorter intermediate ones.
In wet places, Virginia to Florida and Alabama. July-Sept.