Senecioneae is the largest

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

of the

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 ...

, or the sunflower family, comprising over 150 genera and over 3,500 species. Almost one-third of the species in this tribe are placed in the

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 ...

Senecio ''Senecio'' 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. Description Mo ...

''. Its members exhibit probably the widest possible range of form to be found in the entire plant kingdom, and include annuals, minute creeping alpines,

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

and

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

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 ...

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s, climbers, succulents,

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s, and semi-

aquatic plant Aquatic plants, also referred to as hydrophytes, are vascular plants and Non-vascular plant, non-vascular plants that have adapted to live in aquatic ecosystem, aquatic environments (marine ecosystem, saltwater or freshwater ecosystem, freshwater ...

s. Plants in this tribe are responsible for more livestock poisonings than all other plants combined. Its members usually contain liver and kidney toxic and carcinogenic unsaturated pyrrolizidine alkaloids in ''Senecio'' and furanoeremophilanes in '' Tetradymia''. A number of species are well known in

horticulture Horticulture (from ) is the art and science of growing fruits, vegetables, flowers, trees, shrubs and ornamental plants. Horticulture is commonly associated with the more professional and technical aspects of plant cultivation on a smaller and mo ...

Classification

Since the time of Bentham, the "premier systematic botanist of the nineteenth century", considerable efforts have been made to classify and understand the striking morphological diversity in the Senecioneae. The traditional view of the tribe has been that of one huge genus ''Senecio'' plus many other genera which exhibit varying degrees of distinctiveness. Circumscription and delimitation of the tribe have experienced expansions and contractions over the decades as genera and groups of genera have been moved in and out, as was the case for ''

Arnica ''Arnica'' is a genus of perennial plant, perennial, herbaceous plants in the sunflower family (Asteraceae). The genus name ''Arnica'' may be derived from the Greek language, Greek ''wikt:arni, arni'', "lamb", in reference to the plants' soft, h ...

'', '' Liabum'', ''

Munnozia ''Munnozia'' is a genus of flowering plants in the family Asteraceae. It is centered in the Andes.Pruski, J. F. (2012)Studies of Neotropical Compositae – V. ''Munnozia ortiziae'' (Liabeae), a new species from the Andes of Pasco, Peru.Phyton ...

'', '' Schistocarpha'', etc. which have since then been excluded. Of the several potential causes for this constant redefinition the greatest is probably that little is known about its intergeneric relationships or a lack of

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

understanding enhanced by the other problems of conflicting clues from morphological characters, the large size of the tribe, the absence of a precise delimitation or circumscription of ''Senecio'' and the naturalness of these assemblages combined with the imprecise boundaries of the different species themselves. Many segregate genera have been recognized in recent studies, often with circumscriptions derived from selected representative species. Whether the recognition of numerous segregate genera provides a better taxonomy than treating the variation patterns as infrageneric taxa is yet unclear. A respectable case can be made for maintaining ''Senecio'' as a broad concept, at least until revisionary studies at the species level are carried out and the results subjected to critical analyses. Most genera that have been removed from the Senecioneae in the broadest sense have come to rest within the Liabeae or within a broadly circumscribed Heliantheae (e.g., allies in the Arnicinae, Chaenactidinae, or Madiinae; '' Haploesthes'' in the Flaveriinae; and '' Raillardella'' and allies in the Madiinae). Additional information may be found in B. G. Baldwin et al. (2002), H. Robinson (1981), B. Nordenstam (1977–1978) and K. Bremer (1994).

Classification

Genera

References

External links