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..
Coreopsis rosea Nutt. Gen. 2: 179. 1818.
Perennial by slender rootstocks; stems at length much branched, slender, strict, glabrous, 6'-24' high. Leaves opposite, linear, glabrous, entire, obscurely 1-nerved, 1'-2 1/2' long, 1/2'-1" wide, sessile, or the lower petioled; heads slender-peduncled, several or numerous, 6"-12" broad; disk yellow; rays 4-8, pink or rose-colored (occasionally white), oblong to obovate, slightly 3-toothed or sometimes entire; inner bracts of the hemispheric involucre ovate-oblong, acutish or obtuse, glabrous, much longer than the lanceolate outer ones; achenes oblong or linear-oblong, thin, not winged, nearly straight, slightly ribbed on the inner face; pappus a very short truncate crown.
In open swamps, eastern Massachusetts to Georgia, near the coast. July-Aug.