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Senecio Sunset Western Garden Book, 1995:606–607 is a genus of flowering plants in the daisy family (Asteraceae) that includes ragworts and groundsels.
Variously circumscribed taxonomically, the genus Senecio is one of the largest genera of flowering plants. Plants of the World Online currently accepts 1482 species.
In its current circumscription, the genus contains species that are annual plant or perennial herbs, shrubs, small trees, aquatics or climbers.
As no morphological Synapomorphy are known to determine which species belong to the genus or not, no exact species number is known. The genus has an almost worldwide distribution and evolved in the mid- to late Miocene.
The following genera are currently accepted by Plants of the World Online, and contain species that are or have been included within Senecio.
Formerly in Senecio (partial list)
Description
Morphology
The are normally rayed with the heads borne in branched clusters, and usually completely yellow, but green, purple, white and blue flowers are known as well.
Chemistry
Pyrrolizidine alkaloids are found in all Senecio species. These alkaloids serve as a natural to deter or even kill animals that would eat them. Livestock generally do not find them palatable. Senecio species are used as food plants by the of some Lepidoptera species that have developed tolerance for these alkaloids.
Taxonomy
The traditional circumscription of Senecio is artificial, being polyphyletic, even in its new circumscription which is based on genetic data. Despite the separation of many species into other genera, the genus still contains species and is one of the largest genera of flowering plants.
Phylogeny
As of 2007, many genera and the whole tribe were in need of revision. Many species currently placed in the genus need to be transferred to other or new genera, and others have been retransferred to Senecio. In its new delimitation the genus is still not Monophyly.
Etymology
The scientific name, , derives from the latin 'senex' which means "old man".
Selected species
Distribution
The genus Senecio is distributed almost worldwide. It is one of the few genera occurring in all five regions with a Mediterranean climate. Furthermore, species are found in mountainous regions, including tropical alpine-like areas.
See also
External links
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