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..
[Zinnia L. Syst. Ed. 10, 1221. I759-]
Annual or perennal herbs, some species shrubby, with opposite, entire, or sparingly serrate, mostly narrow and sessile leaves, and large or middle-sized heads of both tubular and radiate flowers. Ray-flowers pistillate, yellow, or variegated, persistent on the achene. Disk-flowers perfect, fertile; corolla cylindraceous, its lobes villous. Involucre campanulate to nearly cylindric, its bracts obtuse, dry, firm, appressed, imbricated in 3 series or more, the outer gradually shorter. Receptacle conic or cylindric, chaffy, the chaff subtending and enwrapping the disk-flowers. Style-branches elongated, not appendages. Achenes of the ray-flowers somewhat 3-angled, those of the disk flattened. Pappus of few awns or teeth. [In honor of Paul Crassus, an Italian botanist of the sixteenth century.]
About 12 species, natives of the United States and Mexico. Type species: Chrysogonum peru-vianum L.
Crassina grandiflora Kuntze, Rev. Gen. Pl. 331. 1891.
Perennial, woody at the base, tufted, much branched, rough, 4'-6' high. Leaves rather rigid, linear to linear-lanceolate, entire, 6"-15" long, 1 1/2" wide, or less, connate at the base, acute or acutish, crowded; heads numerous, peduncled, terminating the branches, io"-i8" broad; rays 4 or 5, broad, yellow, rounded, or emarginate, their achenes with a pappus of 2 or 4 awns; involucre campanulate-cylindric, 3"-4" high; style-branches of the disk flowers subulate.
In dry soil, Kansas and Colorado to Texas, Mexico and Arizona. June-Sept.