Species Crosses in Helianthus: III. Delimitation of "Sections"

The genus Helianthus comprises 108 species, according to Watson (1929), although only about 70 would be recognized in a more conservative treatment.Asa Gray (1884) subdivided the genus into "annuals" and "perennials."It is perhaps significant that he failed to give Latin designations to his sections.Watson (1929) resorted to purely artificial groupings, the Rubri, in which the lobes of the disk corollas are red or purple, and the Flavi, in which the lobes are yellowish.The artificiality of this treatment is apparent when it is realized that several species are known in which both colors of disk corollas occur.However, it is true that the red Heiser, Charles Bixler.1965."Species Crosses in Helianthus: III.Delimitation of "Sections"."