Search results for "Senecio"
showing 10 items of 31 documents
Variation in the Senecio aethnensis group (Asteraceae) along an altitudinal gradient
2003
ABSTRACT The variability of the Senecio aethnensis group was investigated through morphometric analyses of seven populations along an altitudinal transect on Mt. Etna (E Sicily). The data obtained show a separation into two groups, one including the populations of the upper and middle belts, at and above 1700 m, the other including the populations from lower altitudes. In the first group a clinal morphological variation in several reproductive and vegetative characters was observed in relation to altitude. The analysis of leaf characters in progeny cultivated under uniform conditions confirmed the differentiation into the two groups, which are to be treated as separate species, i.e. S. aeth…
THE OCCURRENCE OF SENECIO VULGARIS L. VAR. VULGARIS AND S. × HELWINGII BEGER EX HEGI (S. VULGARIS × S. VERNALIS WALDST. ET KIT.) IN ISRAEL
1994
Common Groundsel (Senecio vulgarisL. var.vulgaris(2n = 40)) is widespread in the northern hemisphere. In Israel, judging from a herbarium survey, records taken from the Israel Plant Information Center (ROTEM), and field studies, it has a restricted and widely disjunct pattern of geographical distribution, and, thus, is another example of the comparatively large group of weeds in Israel which are extremely stenochorous. The remarkable gaps in its distribution, from the Upper Golan to Mt. Carmel and to the Jerusalem area, are considered primarily to be the result of paleoclimatic changes, whereas its occurrence outside these centers of distribution is probably related to long-distance dispers…
Seed germination reports of high mountain species native to Mount Etna (Sicily)
2020
The germination ability of five endemic species from the high mountain belt of Mt. Etna were studied; they are Astragalus siculus, Erysimum etnense, Senecio squalidus subsp. aethnensis, Silene italica subsp. sicula, and Tanacetum vulgare subsp. siculum. Mature seeds were collected in the field, within an elevation range of 1700–2000 m a.s.l. Different experimental conditions were tested and the best methods with optimal germination results are provided and compared for each species. First germination records are given for 4 out of 5 of the investigated taxa.
Dual colonization of the Palaearctic from different regions in the Afrotropics bySenecio
2016
Aim Investigation of the geographical origin of Senecio and the colonization of the Palaearctic including the relationship of life-history strategy and elevational distribution in the source area and the colonized area. Location Worldwide with a focus on the Afrotropic and the Palaearctic. Methods Sampling focused on adding species from the Afrotropic to existing datasets of Senecio. Two nuclear markers and three chloroplast markers were amplified and sequenced. Maximum likelihood and Bayesian inference were used to infer phylogeny, divergence times, biogeographical history and life-history strategy evolution. Results Senecio originated most likely during the Mid to Late Miocene in western …
Patterns and causes of incongruence between plastid and nuclear Senecioneae (Asteraceae) phylogenies
2010
One of the longstanding questions in phylogenetic systematics is how to address incongruence among phylogenies obtained from multiple markers and how to determine the causes. This study presents a detailed analysis of incongruent patterns between plastid and ITS/ETS phylogenies of Tribe Senecioneae (Asteraceae). This approach revealed widespread and strongly supported incongruence, which complicates conclusions about evolutionary relationships at all taxonomic levels. The patterns of incongruence that were resolved suggest that incomplete lineage sorting (ILS) and/or ancient hybridization are the most likely explanations. These phenomena are, however, extremely difficult to distinguish beca…
An ITS phylogeny of tribe Senecioneae (Asteraceae) and a new delimitation of Senecio L.
2007
Senecioneae is the largest tribe ofAsteraceae, comprised ofca. 150 genera and 3,000 species. Approximately one-third of its species are placed in Senecio, making it one of the largest genera of flowering plants. Despite considerable efforts to classify and understand the striking morphological diversity in Senecioneae, little is known about its intergeneric relationships. This lack ofphylogenetic understanding is predominantly caused by conflicting clues from morphological characters, the large size ofthe tribe, and the absence of a good delimitation of Senecio. Phylogenetic analyses of nrITS and plastid DNA sequence data were used to produce a hypothesis of evolutionary relationships in Se…
A revision of Gynura (Asteraceae: Senecioneae)
2011
A revision of the paleotropical genus Gynura Cass. is presented. Forty-four species are recognized, of which three are described as new. These are G. daviesiae Vanijajiva & Kadereit, G. villosa Vanijajiva & Kadereit, and G. siamensis Vanijajiva & Kadereit. Gynura dissecta (F. G. Davies) Vanijajiva & Kadereit, G. annua (F. G. Davies) Vanijajiva & Kadereit, and G. aurantiaca (Bl.) DC. subsp. parviflora (F. G. Davies) Vanijajiva & Kadereit are new combinations. An identification key, descriptions, and distribution maps are provided.
Biomonitoring of volcanogenic trace elements using two endemic species (Senecio aethnensis and Rumex aethnensis) on Mt. Etna.
2009
A biomonitoring survey, above treeline level, using two endemic species (Senecio aethnensis and Rumex aethnensis) was performed on Mt. Etna, in order to evaluate the dispersion and the impact of volcanic emissions. Samples of leaves were collected in summer 2008 from 30 sites in the upper part of the volcano (1500-3000 m a.s.l). Acid digestion of samples was carried out with a microwave oven, and 44 elements were analysed by using plasma spectrometry (ICP-MS and ICP-OES). The highest concentrations of all investigated elements were found in the samples collected closest to the degassing craters, and in the downwind sector, confirming that the eastern flank of Mt. Etna is the most impacted b…
Environmental impact of Mt. Etna’s degassing: volcanogenic trace elements bioaccumulation in two endemic plant species (Senecio aethnensis and Rumex …
2010
A biomonitoring survey, above tree line level, using two endemic species (Senecio aethnensis and Rumex aethnensis)was performed on Mt. Etna, in order to evaluate the dispersion and the impact of volcanic atmospheric emissions. Samples of leaves were collected in summer 2008 from 30 sites in the upper part of the volcano (1500-3000 m a.s.l). Acid digestion of samples was carried out with a microwave oven, and 44 elements were analyzed by using plasma spectrometry (ICP-MS and ICP-OES). The highest concentrations of all investigated elements were found in the samples collected closest to the degassing craters, and in the downwind sector, confirming that the eastern flank of Mt. Etna is the mos…
The genetic ghost of an invasion past: colonization and extinction revealed by historical hybridization inSenecio
2011
Hybridization is an important evolutionary factor in the diversification of many plant and animal species. Of particular interest is that historical hybridization resulting in the origin of new species or introgressants has occurred between species now geographically separated by great distances. Here, we report that Senecio massaicus, a tetraploid species native to Morocco and the Canary Islands, contains genetic material of two distinct, geographically separated lineages: a Mediterranean lineage and a mainly southern African lineage. A time-calibrated internal transcribed spacer phylogeny indicates that the hybridization event took place up to 6.18 Ma. Because the southern African lineage…