Heliopsis Pers.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 143

51. Heliopsis Pers. 2

Perennials. Leaves opposite. Capitula solitary, large. Involucral bracts in 2-3 rows. Receptacle conical, with numerous scales. Ligulate florets in 1 row, female, yellow. Tubular florets hermaphrodite. Achenes obtusely 3- to 4-angled; pappus absent or a small, more or less toothed rim.

Literature: T. R. Fisher, Ohio Jour. Sci. 57: 171-191 (1957).