Senecio

Morphology '' flowerheads have the yellow ray florets typical of many species The flower heads are often rayed (though the type species Senecio vulgaris does not have ray florets), 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. 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 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 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 monophyletic. • Aetheolaena • Antillanthus • Barkleyanthus • Bethencourtia (synonym Canariothamnus ) • Brachyglottis • Curio • Dauresia • Dendrophorbium • Dendrosenecio - Giant groundsels native to high-elevation areas of East Africa • Dorobaea • Dresslerothamnus • Elekmania • Hasteola • Herreranthus • Hubertia • Iocenes • Jacobaea • Leonis • Ligularia • Lundinia • Mesogramma • Monticalia • Nelsonianthus • Nesampelos • Oldfeltia • Packera • Pentacalia • Pippenalia • Pittocaulon • Pojarkovia • Psacaliopsis • Pseudogynoxys • Robinsonia (synonym Vendredia ) • Roldana • Sinosenecio • Synotis • Telanthophora • Tephroseris • Zemisia Etymology The scientific name Senecio derives from the latin 'senex' which means "old man". Selected species • Senecio ampullaceus — Texas ragwort, Texas squaw-weed, Texas groundsel, clasping-leaf groundsel • Senecio angulatus — creeping groundsel • Senecio antisanae • Senecio arborescens • Senecio barbertonicus — succulent bush senecio • Senecio bigelovii — nodding groundsel • Senecio brasiliensis — flor-das-almas • Senecio cambrensis — Welsh groundsel, Welsh ragwort • Senecio candicans — angel wings • Senecio casapaltensis (synonym Senecio sanmarcosensis ) • Senecio crassissimus • Senecio decaryi — Madagascar senecio • Senecio elegans — purple groundsel • Senecio falklandicus • Senecio flaccidus — Douglas senecio, threadleaf groundsel, threadleaf ragwort • Senecio gallicus — French groundsel • Senecio glaucus — Jaffa groundsel • Senecio howeanus • Senecio inaequidens — South African ragwort • Senecio iscoensis • Senecio keniophytum • Senecio lamarckianus • Senecio leucanthemifolius — coastal ragwort • Senecio macroglossus — Natal ivy, wax ivy • Senecio madagascariensis — Madagascar ragwort • Senecio neowbsteri – Olympic Mountain groundsel • Senecio oxyriifolius (synonym Senecio tropaeolifolius) — false nasturtium • Senecio patagonicus • Senecio pauciradiatus • Senecio pokohinuensis — Mokohinau groundsel • Senecio pulcher • Senecio scandens — climbing Senecio • Senecio squalidus — Oxford ragwort • Senecio triangularis — arrowleaf groundsel • Senecio vaginatus • Senecio vernalis — eastern groundsel • Senecio viscosus — sticky ragwort • Senecio vulgaris — common groundsel, old-man-in-the-spring 'Formerly in Senecio (partial list)' • Brachyglottis greyi (as S. greyi) • Jacobaea vulgaris (common ragwort; as S. jacobaea) • Pericallis × hybrida (as S. cruentus) • Rugelia nudicaulis — Rugels ragwort • Telanthophora grandifolia (as S. grandifolius ) • Tephroseris papposa (as S. papposus) ==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==