''Senecio'' is a genus of flowering plants in the daisy family (Asteraceae) that includes ragworts and groundsels. Variously circumscription (taxonomy), circumscribed taxonomically, the genus ''Senecio'' is one of the largest genera of flowering plants.

Description

Morphology

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 plant, annual or perennial herbs, shrubs, small trees, aquatics or climbers. The only species which are trees are the species formerly belonging to ''Robinsonia (plant), Robinsonia'' occurring on the Juan Fernández Islands.

Chemistry

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. ''Senecio'' species are used as food plants by the larvae 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 List of the largest genera of flowering plants, largest genera of flowering plants. As no morphological Synapomorphy, 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 and evolved in the mid- to late Miocene.

Phylogeny

As of 2007, 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 Monophyly, monophyletic. Genera that have been included are the following: * ''Aetheolaena'' * ''Culcitum'' * ''Hasteola'' * ''Iocenes'' B. Nord. * ''Lasiocephalus'' Willd. ex Schltdl. * ''Robinsonia (plant), Robinsonia''

Synonyms

The following genera contain species that are or have been included within ''Senecio''. * ''Antillanthus'' B. Nord. * ''Barkleyanthus'' H. Rob. & Brettell * ''Brachyglottis'' J. R. Forst. & G. Forst. * ''Canariothamnus'' B. Nord. * ''Curio (plant), Curio'' P.V. Heath * ''Dauresia'' B. Nord. & Pelser * ''Dendrophorbium'' C. Jeffrey * ''Dendrosenecio'' (Hauman ex Hedberg) B. Nord. - Giant groundsels occurring in the high altitude areas of East Africa * ''Dorobaea'' Cass. * ''Dresslerothamnus'' H. Rob. * ''Elekmania'' B. Nord. * ''Herreranthus'' B. Nord. * ''Hubertia'' Bory * ''Jacobaea'' Mill.''Leonis (plant), Leonis'' B. Nord. * ''Ligularia'' * ''Lundinia'' B. Nord. * ''Mesogramma (plant), Mesogramma'' DC. * ''Monticalia'' C. Jeffrey * ''Nelsonianthus'' H. Rob. & Brettell * ''Nesampelos'' B. Nord., nom. inval. * ''Oldfeltia'' B. Nord. & Lundin * ''Packera'' Á. Löve & D. Löve * ''Pentacalia'' Cass. * ''Pippenalia'' McVaugh * ''Pittocaulon'' H. Rob. & Brettell * ''Pojarkovia'' Askerova * ''Psacaliopsis'' H. Rob. & Brettell * ''Pseudogynoxys'' (Greenm.) Cabrera * ''Pseudojacobaea'' (Hook. f.) R. Mathur * ''Roldana'' La Llave * ''Sinosenecio'' B. Nord. * ''Synotis'' (C. B. Clarke) C. Jeffrey & Y. L. Chen * ''Telanthophora'' H. Rob. & Brettell * ''Tephroseris'' (Rchb.) Rchb. * ''Vendredia'' Baill. * ''Zemisia'' B. Nord.

Etymology

The scientific name, ''wikt:senecio, Senecio'', derives from the latin 'senex' wich means "old man".

Selected species

*''Senecio ampullaceus'' — Texas ragwort, Texas squaw-weed, Texas groundsel, clasping-leaf groundsel *''Senecio angulatus'' L.f. — creeping groundsel *''Senecio antisanae'' *''Senecio arborescens'' *''Senecio barbertonicus'' Klatt — succulent bush senecio *''Senecio bigelovii'' — nodding groundsel *''Senecio bosniacus'' G. Beck — Bosnian ragwort *''Senecio brasiliensis'' (Spreng.) Less. — flor-das-almas *''Senecio candicans'' — angel wings *''Senecio cambrensis'' — Welsh groundsel, Welsh ragwort *''Senecio crassissimus'' *''Senecio elegans'' — purple groundsel *''Senecio falklandicus'' *''Senecio flaccidus'' Less. — Douglas senecio, threadleaf groundsel, threadleaf ragwort *''Senecio gallicus'' Chaix — French groundsel *''Senecio glaucus'' L. — Jaffa groundsel *''Senecio howeanus'' *''Senecio inaequidens'' — South African ragwort *''Senecio iscoensis'' — Hieron. *''Senecio keniophytum'' *''Senecio lamarckianus'' *''Senecio leucanthemifolius'' Poir. — coastal ragwort *''Senecio madagascariensis'' — Madagascar ragwort *''Senecio macroglossus'' — Natal ivy, wax ivy *''Senecio neowbsteri'' Olympic Mountain groundsel *''Senecio patagonicus'' *''Senecio pauciradiatus'' *''Senecio pokohinuensis'' — Mokohinau groundsel *''Senecio pulcher'' *''Senecio sanmarcosensis'' *''Senecio scandens'' — climbing Senecio *''Senecio squalidus'' — Oxford ragwort *''Senecio trapezuntinus'' *''Senecio triangularis'' — arrowleaf groundsel *''Senecio tropaeolifolius'' — false nasturtium *''Senecio vaginatus'' *''Senecio vernalis'' — eastern groundsel *''Senecio viscosus'' — sticky ragwort *''Senecio vulgaris'' — common groundsel, old-man-in-the-spring Formerly in ''Senecio'' * ''Brachyglottis greyi'' (as ''S. greyi'') * Pericallis × hybrida, ''Pericallis'' × ''hybrida'' (as ''S. cruentus'') * ''Rugelia nudicaulis'' — Rugels ragwort

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.

References

External links

* * * * * * * * * * * * * * * * * {{Authority control Senecio, Asteraceae genera Taxa named by Carl Linnaeus