22-448: Some 1,250; see text Dendrosenecio Jacobaea L. Vendredia Baill. Culcitium Humb. & Bonpl Senecio / s ɪ ˈ n iː ʃ i . oʊ / 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. The flower heads are normally rayed with
44-416: 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. The traditional circumscription of Senecio is artificial, being polyphyletic , even in its new circumscription which is based on genetic data . Despite
66-566: A result, old plants have the appearance of candelabras the size of telephone poles, each branch with a terminal rosette. Dendrosenecio varies geographically between mountain ranges, and altitudinally on a single mountain. There has been disagreement among botanists as to which populations of Dendrosenecio warrant recognition as species, and which should be relegated to the status of subspecies or variety. The following list, taken from Knox & Palmer, will be used for articles about this genus. Groundsels of several species are found throughout
88-403: 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 c. 1,250 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
110-425: 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. Dendrosenecio Dendrosenecio is a genus of flowering plants in the sunflower family . It is a segregate of Senecio , in which it formed the subgenus Dendrosenecio . Its members,
132-457: Is found at the lower altitudes of the range where the species grows and Dendrosenecio battiscombei grows at the same altitudes as D. keniensis but in the wetter environments. The other mountains which are not tall enough to have a "big one at the top" have the two, one species for the drier land and one for the damper environments or just one because the environment is not so extreme. This simplification works extremely well as an introduction to
154-412: Is known. The genus has an almost worldwide distribution and evolved in the mid- to late Miocene . 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 . Genera that have been included are
176-797: The Rwenzori Mountains on the Uganda/ Democratic Republic of Congo (DRC) border, the Virunga Mountains on the borders of Rwanda , Uganda and the DRC, and Mitumba Mountains ( Mount Kahuzi and Mount Muhi ) in the east of the DRC. With the exception of D. eric-rosenii , which occurs on several of the mountains of the Albertine Rift (Rwenzori, Virunga and Mitumba Mountains), and D. battiscombei and D. keniodendron , which are shared by Mount Kenya and
198-404: The giant groundsels , are native to the higher altitude zones of ten mountain groups in equatorial East Africa , where they form a conspicuous element of the flora. They have a giant rosette habit, with a terminal leaf rosette at the apex of a stout woody stem. When they bloom, the flowers form a large terminal inflorescence. Concomitantly, two to four lateral branches are normally initiated. As
220-488: The tree line forming "islands in the sky" or isolated habitats. These predominantly volcanic peaks further simplify the model by their age and arrangement around the Lake Victoria basin and proximity to the equator . The species found on Mount Kenya are by far the best model for altitudinal variation. Dendrosenecio keniodendron is the species which grows at the highest of altitudes, Dendrosenecio keniensis
242-464: The Aberdare Range, the species are individually confined to a single range. In several of the ranges different species, or subspecies, are found at different heights. The mountains of central and eastern Africa are an almost ideal model system for studying speciation and adaptation in plants. The mountains rise far above the surrounding plains and plateaus, tall enough to reach above
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#1732766051892264-465: The Lobelia more certainly tetraploid (four sets; 4x), their adaptive radiations involved no further change in chromosome number. The cytological uniformity within each group, while providing circumstantial evidence that they descended from a single ancestor and simplifying interpretations of cladistic analyses, provides neither positive nor negative support for a possible role of polyploidy in evolving
286-425: The genus Senecio is one of the largest genera of flowering plants. 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
308-463: The giant groundsel of East Africa with one exception, Kilimanjaro who has the one species that lives at the top and only one species that lives below; subspecies and varieties living in the moister environments. The communities of giant Dendrosenecio and giant lobelias found on these African mountains are an exceptional example of parallel or convergent evolution and repeated convergent evolution between these two groups; providing evidence that
330-458: The giant-rosette growth-form. [REDACTED] Media related to Dendrosenecio at Wikimedia Commons Senecio Some 1,250; see text Dendrosenecio Jacobaea L. Vendredia Baill. Culcitium Humb. & Bonpl Senecio / s ɪ ˈ n iː ʃ i . oʊ / is a genus of flowering plants in the daisy family ( Asteraceae ) that includes ragworts and groundsels . Variously circumscribed taxonomically,
352-565: 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 . Pyrrolizidine alkaloids are found in all Senecio species. These alkaloids serve as
374-429: The number of chromosomes in each cell) for the giant Dendrosenecio is n = 50, and for the giant lobelias. Specifically Lobeliaceae , Lobelia subgenus Tupa section Rhynchopetalum it is n = 14. Only five of the 11 species of giant senecio and three of the 21 species of giant lobelia from eastern Africa remain uncounted. Although both groups are polyploid , Dendrosenecio is presumed to be decaploid (ten sets; 10x) and
396-419: 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 . 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 . As of 2007, many genera and
418-487: The species formerly belonging to Robinsonia occurring on the Juan Fernández Islands . 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. The traditional circumscription of Senecio
440-436: The unusual features of these plants are an evolutionary response to a challenging habitat and an environment which can be easily described for biogeographic analysis. Little variation was found in molecular phylogeny among the 40 recorded giant senecio collections (40 accessions), yet as a group they differ significantly from Cineraria deltoidea , the closest known relative. The gametophytic chromosome number (is
462-598: 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 . Genera that have been included are the following: The following genera contain species that are or have been included within Senecio . The scientific name , Senecio , means "old man". Formerly in Senecio The genus Senecio
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#1732766051892484-641: The world as common roadside weeds, but nowhere except in the highlands of Africa do they exhibit such large tree forms. Theodore Roosevelt 1914 The giant groundsels are found in the alpine zone of the mountains of equatorial East Africa - Mount Kilimanjaro and Mount Meru in Tanzania , Mount Kenya , the Aberdare Range , and Cherangani Hills in Kenya , Mount Elgon on the Uganda /Kenya border,
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