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 perennial mostly branched herbs, with opposite, sessile or connate-perfoliate, broad dentate leaves, and large peduncled heads of tubular and radiate yellow flowers. Involucrte depressed-hemispheric, its principal bracts 4, large and foliaceous, inserted in 1 series; inner bracts 6-15, small, subtending the pistillate ray-flowers. Receptacle conic, chaffy, the chaff concave, enwrapping the perfect fertile disk-flowers, the corollas of which are slender and S-toothed. Anthers entire or minutely 2-toothed at the base. Style-branches of the disk-flowers hispid, tipped with elongated appendages. Achenes thick, 4-sided, truncate at the summit. Pappus none, or of several short scales. [Greek, 4-angled-case, referring to the involucre.]
Four known species, natives of the southern United States and northern Mexico, the following typical.
Tetragonotheca helianthoides L. Sp. Pl. 903. 1753.
Viscidly pubescent; stem brancned or simple, 1°-2 1/2° high Leaves ovate, ovate-oblong, or somewhat rhomboid, thin, coarsely and unequally dentate, pinnately veined, acute at the apex, narrowed at the sessile or somewhat clasping base, 2'-6' long, i'-j' wide; heads usually few, 11/2'-3' broad; involucre 4-angled in the bud, its principal bracts broadly ovate, acute; rays 6-10, strongly parallel-nerved, 2-3-toothed; corolla-tube villous below; achenes 4-sided, or nearly terete; pappus none.
In dry soil, Virginia to Tennessee, Florida and Alabama. May-June. Sometimes flowering again in autumn.