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, much branched, glabrous herbs, with small alternate entire leaves, and very numerous small heads of both tubular and radiate yellow flowers, solitary or clustered at the ends of the branches. Involucre ovoid or hemispheric, its bracts coriaceous, imbricated in few series. Receptacle naked. Ray-flowers pistillate. Disk-flowers perfect, but sterile, or staminate. Pappus of the ray-flowers obsolete or coroniform, that of the disk-flowers of 5-20 subulate scales or bristles somewhat united at the base. Achenes pubescent. [Greek, chaff-around.]
Two known species, natives of the south-central United States, the following typical.
Brachyris dracunculoides DC. Mem. Soc. Phys. Gen.
7: Part 2, 265. pl. 1. 1836. Amphiachyris dracunculoides Nutt. Trans. Am. Phil.
Soc. (II.) 7: 313. 1841.
Annual, slender, much branched, 6'-18' high, the branches ascending. Leaves linear, 6"-18" long, 1"-2" wide, acutish, the uppermost almost filiform; heads solitary at the ends of short branches, 10-30-flowered, about 2" high; involucre hemispheric, its bracts oval, obtuse; rays 5-10, about as long as the involucre; disk-flowers mostly staminate, their ovaries abortive, their pappus of 5-8 subulate aristate scales, united into a short cup at the base.
In dry soil, Missouri and Kansas to Texas and New Mexico. Found adventive at Easton, Penna. Sept.-Oct.