Tithonia
The Tithonia Germanized, sometimes called Tithonien, are a genus in the subfamily of herbaceous within the sunflower family ( Asteraceae). The botanical genus name refers to Tithonos from Greek mythology, the son of Laomedon and the lover of Eos (the Roman equivalent Aurora is so Tithonia species are also sometimes called favorite of Aurora ). In the genus Tithonia there are about nine to eleven species. The varieties fewer species are used as ornamental plants and, regardless of what kind they are called Mexican sunflowers.
Description
Tithonia species grow as annuals to perennial herbaceous plants, or if there are woody species form: rarely subshrubs, shrubs and trees. You can reach depending on the type usually stature heights of about 0.70 to 5, rarely up to 7 meters. The upright stems are often branched. The upper area often against constantly and otherwise mostly alternate on the stems arranged distributed leaves are petiolate or sessile. The leaf blade is easy with a rare, usually three or five leaf veins starting at or near the Spreitenbasis. The leaf margin is smooth or sometimes three to five lobes. The leaf surfaces are smooth to hairy differently depending on the type.
The long -stalked little head shaped buds appear singly and terminally. The flower heads have diameters from 1 to up to over 2 centimeters. In two to five rows are 12 to more than 28 bracts; they are different in shape and size almost equal to strong. The inflorescence floors are hemispherical to convex. There are chaff leaves present. The flower heads contain eight to 30 ray florets and usually 40 to 120, rarely up to 200 florets. The ungeschlechtigen, sterile, zygomorphic ray florets ( = ray florets ) are yellow to orange ( also in breeding red). The hermaphrodite, fertile florets ( = disc florets ) are usually yellow with five corolla lobes. The black, brown or straw-colored anthers have ovoid appendage. The two stigma lobes have appendages.
The three -, four -edged or biconvex achenes are brown or black. The pappus is crown shaped and consists of two more or less overgrown shed or he is missing.
Systematics and distribution
The natural distribution of the genus Tithonia ranges from the southwestern United States through Mexico to Central America. Some species (especially Tithonia diversifolia ) are invasive plants in many areas of the world, for example in the southeastern United States, the Caribbean, South America and the Old World.
The first publication of the genus Tithonia was made in 1789 by René Desfontaines in Antoine -Laurent de Jussieu: Genera Plantarum, p 189 The genus belongs to the subtribe Tithonia Helianthinae from the tribe Heliantheae in the subfamily of herbaceous within the sunflower family ( Asteraceae). A synonym for Tithonia Desf. ex Juss. is Mirasolia ( Sch.Bip. ) Benth.
In the genus Tithonia there are about ten to eleven species. Here is a list of all types:
- Tithonia calva Sch.Bip.
- Mexican sunflower ( Tithonia diversifolia ( Hemsl. ) Gray ): The natural range is probably Florida, Texas and Mexico. It is an invasive plant in many parts of the world. Your common name in Cuba due to their use is " Margaritoneladasa " or " Arnica de la Tierra ". In Colombia, it is called because of their color " Mirasol " or " Botón de Oro ".
- Torch Flower, Mexican sunflower or Round-leaved Tithonia ( Tithonia rotundifolia (Mill.) SFBlake ): As an ornamental plant, it is usually cultivated as an annual. Your Spanish common name is " clavel de muerto " - translated as " clove of the Dead". The natural range is probably Florida, Louisiana and Mexico. It is an invasive plant in many parts of the world.
- Tithonia fruticosa S.Canby & Rose
- Tithonia hondurensis La Duke
- Tithonia humilis Kuntze
- Tithonia longiradiata ( Bertol. ) S.F.Blake
- Tithonia pedunculata Cronquist
- Tithonia recurrent A.Gray ex Hemsl.
- Tithonia thurberi A.Gray: It grows in waste places, in canyons and rivers at altitudes between 900 and 1000 meters in Arizona and the Mexican state of Sonora.
- Tithonia tubiformis ( Jacq. ) Cass.
No longer belongs to the genus:
- Tithonia argophylla DCEaton ⇒ Enceliopsis argophylla ( DCEaton ) A.Nelson
Swell
- John C. La Duke: Tithonia. In: Flora of North America Editorial Committee ( eds.): Flora of North America North of Mexico. Volume 21: Magnoliophyta: unranked, part 8: Asteraceae, part 3 ( Heliantheae, Eupatorieae ), Oxford University Press, New York / Oxford et al 2006, ISBN 0-19-530565-5, p 138, online.
- John C. La Duke: Revision of Tithonia. In: Rhodora. Volume 84, No. 840, 1982, pp. 453-522, online.
- Eduardo Morales: Estimating phylogenetic inertia in Tithonia ( Asteraceae): A comparative approach. In: Evolution. Volume 54, No. 2, 2000, pp. 475-484, DOI: 10.1111/j.0014-3820.2000.tb00050.x.