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..
Erect or diffuse branching pubescent or hirsute herbs, with opposite leaves, and small peduncled terminal and axillary heads of tubular and radiate whitish flowers. Involucre hemispheric or broadly campanulate, its bracts imbricated in about 2 series, nearly equal, of the outer longer. Receptacle flat or convex, chaffy, the chaff awn-like, subtending the achenes. Ray-flowers pistillate, fertile. Disk-flowers perfect, mostly fertile, their corollas tubular, 4-toothed or rarely 5-toothed. Anthers entire or minutely 2-toothed at the base. Style-branches of the disk-flowers with obtuse or triangular tips. Achenes thick, those of the rays 3-sided or 4-sided, those of the disk compressed. Pappus none, or of a few short teeth. [Name changed from Verbena.]
About 4 species, mostly of tropical distribution, the following typical.
Verbesina alba L. Sp. Pl. 902. 1753.
Eclipta erecta L. Mant. 2: 286. 1771.
Eclipta procumbens Michx. Fl. Bor. Am. 2: 129. 1803.
Eclipta alba Hassk. Pl. Jav. Rar. 528. 1848.
Annual, rough with appressed pubescence, erect or diffuse, 6'-3° high. Leaves lanceolate, oblong-lanceolate or linear-lanceolate, acute or acuminate, denticulate or entire, narrowed to a sessile base, or the lower peti-oled, 1'-5' long, 2"-10" wide; heads commonly numerous, 3"-6" broad, nearly sessile, or slender-peduncled; rays short, nearly white; anthers brown; achenes 4-toothed, or at length truncate.
Along streams, and in waste places, Massachusetts to Illinois, Nebraska, Florida, Texas and Mexico. Naturalized from the south in its northeastern range and widely distributed in warm regions as a weed. July-Oct.