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, mostly tomentose or woolly herbs, with alternate and basal leaves, and large heads of both tubular and radiate yellow flowers. Involucre hemispheric or campanulate, its bracts imbricated in several series, the outer often foliaceous. Receptacle flat or convex, areolate or foveolate, not chaffy. Ray-flowers pistillate, their ligules 3-toothed. Disk-flowers perfect, their corollas tubular, 5-toothed. Anthers sagittate at the base, the auricles caudate. Style-branches of the disk-flowers linear, obtuse. Achenes 4-5-ribbed; pappus of capillary rough bristles in our species. [The ancient Latin name.]
About 90 species, natives of Europe, Asia and Africa, the following typical.
Inula Helenium L. Sp. Pl. 881. 1753.
Stems tufted from large thick roots, simple or rarely somewhat branched, 2°-6° high, densely pubescent above. Leaves large, broadly oblong, rough above, densely pubescent beneath, denticulate, the basal ones acute at each end, long-petioled, 10-20' long, 4'-8' wide; stem leaves sessile, or cordate-clasping at the base, acute at the apex, smaller; heads solitary or few, terminal, stout-peduncled, 2-4' broad; involucre hemispheric, nearly 1' high, its outer bracts ovate, foliaceous, pubescent; rays numerous, linear; achenes glabrous, 4-sided.
Along roadsides and in fields, Nova Scotia to Ontario and Minnesota, south to North Carolina and Missouri. Naturalized from Europe. Native also in Asia. Scabwort. Horse-elder. Yellow star-wort. Elfdock. Elfwort. Wild sunflower.