Tithonia is a genus of flowering plants in the tribe Heliantheae within the family Asteraceae.Jussieu, Antoine Laurent de. 1789. Genera Plantarum 189 in Latin
Tithonia has a center of distribution in Mexico but with one species extending into the Southwestern United States and several native to Central America. Two species, T. diversifolia and T. rotundifolia, are widely cultivated and have escaped to become weeds in tropical and subtropical areas around the world. T. rotundifolia makes a nice fresh cut flower, flowering in mid- to late-summer in the Northern hemisphere. The distinguishing feature of the genus is the peduncle, which is fistulose (meaning hollow and flaring toward the apex). The plants are coarse annual or perennial herbs or shrubs, and one species, T. koelzii, is a small tree.
Species Plants of the World Online includes:Plants of the World Online: Tithonia Desf. ex Juss. (retrieved 14 August 2023)Flann, C (ed) 2009+ Global Compositae Checklist Tithonia brachypappa B.L.Rob. - San Luis Potosí Tithonia calva Sch.Bip. - Durango, Sinaloa Tithonia diversifolia (Hemsl.) A.Gray – tree marigold - Mexico, Central America; naturalized in Asia, Australia, Africa, South America, Florida, Texas, various oceanic islands Tithonia fruticosa Canby & Rose - Chihuahua, Durango, Sonora, Sinaloa Tithonia hondurensis La Duke - Belize, Honduras Tithonia koelzii McVaugh - Jalisco Tithonia longiradiata (Bertol.) S.F.Blake - Mexico, Central America (synonym T. pittieri (Greenm.) S.F.Blake) Tithonia paneroi (B.L.Turner) E.E.Schill. & Panero Tithonia pedunculata Cronquist - Oaxaca Tithonia rotundifolia (Mill.) S.F.Blake - Mexico, Central America; naturalized in Florida, Louisiana, South America (synonym T. tagetiflora Desf.) Tithonia thurberi Gray – Arizona sunflower weed - Chihuahua, Sonora, Arizona (Pima County) Tithonia tubaeformis (Jacq.) Cass. - Mexico, Central America; naturalized in Argentina (synonym T. helianthoides Bernh.) Formerly included see Comaclinium, Enceliopsis, Lasianthaea, Viguiera
References
La Duke, J. C. 1982. Revision of Tithonia. Rhodora 84: 453–522.
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