Tithonia

Tithonia is a genus of flowering plants in the tribe Heliantheae within the family Asteraceae.

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:

1. Tithonia brachypappa <small>B.L.Rob.</small> - San Luis Potosí
2. Tithonia calva <small>Sch.Bip.</small> - Durango, Sinaloa
3. Tithonia diversifolia <small>(Hemsl.) A.Gray</small> &ndash; tree marigold - Mexico, Central America; naturalized in Asia, Australia, Africa, South America, Florida, Texas, various oceanic islands
4. Tithonia fruticosa <small>Canby & Rose</small> - Chihuahua, Durango, Sonora, Sinaloa
5. Tithonia hondurensis <small>La Duke</small> - Belize, Honduras
6. Tithonia koelzii <small>McVaugh</small> - Jalisco
7. Tithonia longiradiata <small>(Bertol.) S.F.Blake</small> - Mexico, Central America (synonym T. pittieri <small>(Greenm.) S.F.Blake</small>)
8. Tithonia paneroi <small>(B.L.Turner) E.E.Schill. & Panero</small>
9. Tithonia pedunculata <small>Cronquist</small> - Oaxaca
10. Tithonia rotundifolia <small> (Mill.) S.F.Blake</small> - Mexico, Central America; naturalized in Florida, Louisiana, South America (synonym T. tagetiflora <small>Desf.</small>)
11. Tithonia thurberi <small>Gray</small> &ndash; Arizona sunflower weed - Chihuahua, Sonora, Arizona (Pima County)
12. Tithonia tubaeformis <small>(Jacq.) Cass.</small> - Mexico, Central America; naturalized in Argentina (synonym T. helianthoides <small>Bernh.</small>)

Formerly included

see Comaclinium, Enceliopsis, Lasianthaea, Viguiera

References

• La Duke, J. C. 1982. Revision of Tithonia. Rhodora 84: 453–522.

External links