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..
An annual caulescent herb, with smooth and glaucous foliage, and alternate broad thickish. entire or slightly serrate, 1-ribbed, clasping leaves. Heads radiate, showy. Involucre flat, many-flowered, of few narrow, somewhat foliaceous bracts. Receptacle slender, with early deciduous chaffy scales. Ray-flowers few, neutral, the rays yellow or often brownish-purple at the base. Disk-flowers perfect, fertile, brownish, their corollas 5-lobed. Style-branches with small pubescent appendages. Achenes terete or nearly so, not angled, striate and minutely transversely wrinkled. Pappus wanting. [Greek, dragon-like, referring to the appendaged style-branches.]
A monotypic genus of the southeastern United States.
Rudbeckia amplexicaulis Vahl, Act. Havn. 2: 29. pl. 4.
1783. Dracopis amplexicaulis Cass.; DC. Prodr. 5: 558. 1836.
Annual; glabrous throughout, somewhat glaucous; stem branched, grooved, 1°-2° high, the branches ascending. Leaves entire or sparingly toothed, 1 -ribbed, reticulate-veined, the lower oblong to spatulate, sessile, the upper ovate, ovate-oblong, or lanceolate, acute, cordate-clasping; heads solitary at the ends of the branches, long-peduncled, about 2' broad; bracts of the involucre few, lanceolate, acuminate; rays yellow, or sometimes brown at the base; disk ovoid-oblong, often becoming 1' high; achenes not angled, obliquely attached to the elongated receptacle; chaff at length deciduous.
In wet soil, Missouri to Oklahoma, Louisiana and Texas. June-Aug.