Senecio

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Senecio
Illustration Senecio vulgaris0.jpg
Senecio vulgaris, an illustration from 1885.
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Asteroideae
Tribe: Senecioneae
Genus: Senecio
L.
Type species
Senecio vulgaris
Species

Some 1,250; see text

Synonyms[1]

Dendrosenecio
Jacobaea L.
Vendredia Baill.
Culcitium Humb. & Bonpl

Senecio /sɪˈnʃi./[2] 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.

Description[edit]

Morphology[edit]

The flower heads 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.

In its current circumscription, the genus contains species that are annual or perennial herbs, shrubs, small trees, aquatics or climbers. The only species which are trees are the species formerly belonging to Robinsonia occurring on the Juan Fernández Islands.[3]

Chemistry[edit]

Pyrrolizidine alkaloids are found in all Senecio species. These alkaloids serve as a natural biocides to deter or even kill animals that would eat them. Livestock generally do not find them palatable.[4] Senecio species are used as food plants by the larvae of some Lepidoptera species that have developed tolerance for these alkaloids.

Taxonomy[edit]

The traditional circumscription of Senecio is artificial, being polyphyletic, even in its new circumscription which is based on genetic data.[5][6] Despite the separation of many species into other genera, the genus still contains c. 1,250 species and is one of the largest genera of flowering plants.[7]

As no morphological synapomorphies 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[5] and evolved in the mid- to late Miocene.[8]

Phylogeny[edit]

Many genera and the whole tribe are 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 monophyletic.[5]

Genera that have been included are the following:[5]

Synonyms[edit]

Some of the popular succulent species that were included within Senecio, such as Senecio serpens (pictured) and Senecio rowleyanus, are now placed in the Curio genus.

The following genera contain species that are or have been included within Senecio.[5]

Etymology[edit]

The scientific name, Senecio, means "old man".

Selected species[edit]

S. barbertonicus Succulent Bush Senecio
S. haworthii Woolly Senecio
Senecio elegans (redpurple ragwort)

Formerly in Senecio

Distribution[edit]

The genus Senecio is distributed almost worldwide.[5] 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[edit]

References[edit]

  1. ^ a b c Germplasm Resources Information Network (GRIN) (2007-05-04). "Genus: Senecio L." Taxonomy for Plants. USDA, ARS, National Genetic Resources Program, National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved 2008-02-27.
  2. ^ Sunset Western Garden Book, 1995:606–607
  3. ^ Pelser, Pieter B.; Tepe, Eric J.; Kennedy, Aaron H.; Watson, Linda E. (2013-06-10). "The fate of Robinsonia (Asteraceae): sunk in Senecio , but still monophyletic?". Phytotaxa. 5 (1): 31–46. doi:10.11646/phytotaxa.5.1.2. ISSN 1179-3163.
  4. ^ Taylor, Ronald J. (1994) [1992]. Sagebrush Country: A Wildflower Sanctuary (rev. ed.). Missoula, MT: Mountain Press Pub. Co. p. 156. ISBN 0-87842-280-3. OCLC 25708726.
  5. ^ a b c d e f Pelser, Pieter B.; Nordenstam, Bertil; Kadereit, Joachim W.; Watson, Linda E. (2007). "An ITS Phylogeny of Tribe Senecioneae (Asteraceae) and a New Delimitation of Senecio L". Taxon. 56 (4): 1077. doi:10.2307/25065905. JSTOR 25065905.
  6. ^ Passalacqua, Nicodemo G.; Peruzzi, Lorenzo; Pellegrino, Giuseppe (August 2008). "A Biosystematic Study of the Jacobaea maritima Group (Asteraceae, Senecioneae) in the Central Mediterranean Area". Taxon. 57 (3): 893–906. doi:10.1002/tax.573018. JSTOR 27756716.
  7. ^ Frodin, David G. (2004). "History and concepts of big plant genera". Taxon. 53 (3): 753–76. doi:10.2307/4135449. JSTOR 4135449.
  8. ^ Pelser, Pieter B.; Kennedy, Aaron H.; Tepe, Eric J.; Shidler, Jacob B.; Nordenstam, Bertil; Kadereit, Joachim W.; Watson, Linda E. (2010-05-01). "Patterns and causes of incongruence between plastid and nuclear Senecioneae (Asteraceae) phylogenies". American Journal of Botany. 97 (5): 856–873. doi:10.3732/ajb.0900287. ISSN 0002-9122. PMID 21622451.
  9. ^ Norton, D.A. (1986). "Recent changes in the names of New Zealand tree and shrub species" (PDF). New Zealand Journal of Forestry. 31: 39–40.
  10. ^ Sean Claes (2007-04-16). "Proceed With Caution". Kyle, Texas Daily Photo. Retrieved 2008-04-10.
  11. ^ Rines, George Edwin, ed. (1920). "German Ivy" . Encyclopedia Americana.
  12. ^ Ripley, George; Dana, Charles A., eds. (1879). "German Ivy" . The American Cyclopædia.

External links[edit]