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..
Perennial or biennial herbs, sometimes woody at the base, with alternate sessile or clasping leaves, usually spinulose-dentate, and rather large heads of both discoid and radiate yellow flowers, solitary at the ends of the branches (rays rarely wanting). Involucre hemispheric or depressed, its bracts imbricated in several or many series, usually subulate-tipped. Receptacle flat or convex, naked, foveolate. Ray-flowers fertile. Disk-flowers perfect, or sometimes only staminate. Anthers obtuse and entire at the base. Style-branches narrow, flattened, their appendages linear or lanceolate. Achenes short, thick, sometimes compressed, glabrous, 4-5-ribbed. Pappus of 2-8 soon deciduous awns or bristles. [Named for Prof. H. Grindel, of Riga, 1776-1836.]
About 30 species, natives of western North America, Peru and Chile. Besides the following, some 15 others occur in the western and southwestern parts of North America. Known as Gum-plant or Tar-weed. Type species: Grindelia inuloides Willd.
Leaves spatulate or oblong, obtuse or obtusish; achenes truncate; bracts squarrose.
1. G. squarrosa.
Leaves linear or linear-oblong, acute; achenes 1-2-toothed; bracts not squarrose.
2. G. lanceolata.
Glabrous, erect or ascending, branched, 10'-2° high. Leaves oblong or oblong-spatulate, obtuse, more or less clasping at the base, sharply spinulose-dentate, sometimes laciniate, 1/2'-1 1/2' long, 3"-6" wide; heads io"-i,5" broad, very glutinous; bracts of the involucre linear-lanceolate, subulate-tipped, strongly squarrose; achenes truncate, those of the outer flowers usually thicker than those of the inner; rays up to 1' long or wanting; pappus of 2 or 3 awns.
In dry soil, Illinois and Minnesota to Manitoba, Missouri, Texas, Arizona and Mexico. Adventive in southern New Jersey, Pennsylvania and New York. June-Sept.
Slender, erect, glabrous, branched, about 2° high. Leaves lanceolate or linear, acute at the apex, sessile or clasping at the base, spinulose-dentate, laciniate, or the upper entire, 1'-2' long, 2"-5" wide; heads nearly as large as those of the preceding species; bracts of the involucre linear-subulate, the inner erect, the outer spreading; achenes 1-2-toothed; pappus of 1 or 2 awns.
In dry soil, Tennessee to Missouri, Kansas, Louisiana and Texas. July-Sept.