''Senecio'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of flowering plants in the daisy family (

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

) that includes ragworts and groundsels. Variously 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 or

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

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 The Juan Fernández Islands () are a sparsely inhabited series of islands in the South Pacific Ocean, reliant on tourism and fishing. Situated off the coast of Chile, they are composed of three main volcanic islands: Robinson Crusoe Island, R ...

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

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of some

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

species that have developed tolerance for these alkaloids.

Taxonomy

The traditional circumscription of ''Senecio'' is artificial, being

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

, even in its new circumscription which is based on genetic data. Despite the separation of many

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

into other genera, the genus still contains species and is one of the largest genera of flowering plants. 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 and evolved in the mid- to late

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

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

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. Genera that have been included are the following: * '' Aetheolaena'' * ''Culcitum'' * '' Hasteola'' * '' Iocenes'' B. Nord. * '' Lasiocephalus'' Willd. ex Schltdl. * '' 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'' 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 East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

* '' Dorobaea'' Cass. * '' Dresslerothamnus'' H. Rob. * '' Elekmania'' B. Nord. * '' Herreranthus'' B. Nord. * '' Hubertia'' Bory * '' Jacobaea'' Mill.'' Leonis'' B. Nord. * '' Ligularia'' * '' Lundinia'' B. Nord. * '' 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 In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

, '' 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'' (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 A Mediterranean climate ( ), also called a dry summer climate, described by Köppen and Trewartha as ''Cs'', is a temperate climate type that occurs in the lower mid-latitudes (normally 30 to 44 north and south latitude). Such climates typic ...

. Furthermore, species are found in mountainous regions, including tropical alpine-like areas.

References

External links

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