| Abstract: | Heiser , CHARLES B., Jr . (Indiana U., Bloomington), and Dale M. Smith . The origin of Helianthus multiflorus. Amer. Jour. Bot. 47(10): 860–865. Illus. 1960.—The cultivated ornamental sunflower, Helianthus multiflorus L., has been known since 1591 when it was described from Europe by Tabernaemontanus. Both Gray and Bailey concluded that it was a variety of H. decapetalus. The plant is invariably sterile and Dod was first to suggest a hybrid origin from H. annuus and H. decapetalus. Helianthus multiflorus has been found to be triploid (2n = 51) and at meiosis generally shows 17 bivalents and 17 univalents. Morphologically, the plant is similar to H. decapetalus (n = 34) but differs from it in the more hispid stem, broader leaves and phyllaries, and other characters, all of which could have been derived from H. annuus (n = 17). The artificial hybrid between H. decapetalus and H. annuus, while not readily obtained, has been secured, and the hybrid is rather similar to H. multiflorus. It is concluded that this taxon most likely originated in Europe from spontaneous hybridization between H. decapetalus and H. annuus, following the introduction of these species from North America. |
