tribe
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English language, English is in the discipline of anthropology. This definition is contested, in p ...
of the
Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
, 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 ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
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
Mor ...
''. Its members exhibit probably the widest possible range of form to be found in the entire plant kingdom, and include annuals, minute creeping
alpines
Alpines is a British duo based in Kingston upon Thames in South London, made up of Bob Matthews (guitar and production) and Catherine Pockson (pianist, singer and songwriter). Since forming in 2010, the band has toured and supported The Naked a ...
,
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 t ...
and
evergreen
In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
s,
shrub
A shrub (often also called a 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 ...
s,
climbers
Climber may refer to:
*Climber, a participant in the activity of climbing
*Climber, general name for a vine
*Climber, or climbing specialist, a road bicycle racer who can ride especially well on highly inclined roads
* Climber (BEAM), a robot that ...
,
succulents
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
,
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, including only woody plants with secondary growth, plants that are ...
s, and semi-
aquatic plant
Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...
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
''Tetradymia'' is a genus of North American shrubs in the groundsel tribe within the sunflower family.
A number of species are well known in
horticulture
Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
.
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, herbaceous plants in the sunflower family (Asteraceae). The genus name ''Arnica'' may be derived from the Greek '' arni'', "lamb", in reference to the plants' soft, hairy leaves. ''Arnica'' is also known by th ...
'', ''
Liabum
''Liabum'' is a genus of South American flowering plants in tribe Liabeae of the family Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the o ...
'', ''
Munnozia
''Munnozia'' is a genus of flowering plants in the family Asteraceae. It is centered in the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland a ...
'', ''
Schistocarpha
''Schistocarpha'' is a genus of flowering plants in the tribe Millerieae within the family Asteraceae.
; Species
* ''Schistocarpha bicolor'' Less. - Central America, southern Mexico
* '' Schistocarpha croatii'' H.Rob. - Panamá
* ''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 (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
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
Liabeae is a tribe in the plant family Asteraceae. It is endemic to the Neotropics, where it is most diverse in the northern and central Andes.Dillon, M. O., et alChapter 27: Liabeae.In: Funk, V. A., et al. (eds.) ''Systematics, Evolution, and Bi ...
or within a broadly circumscribed
Heliantheae
The Heliantheae (sometimes called the sunflower tribe) are the third-largest tribe in the sunflower family (Asteraceae). With some 190 genera and nearly 2500 recognized species, only the tribes Senecioneae and Astereae are larger. The name is ...
Madiinae
Madieae is a Tribe (biology), tribe of flowering plants in the family Asteraceae. It is sometimes considered a subtribe of Heliantheae. Notable species include the tarweeds of the Western United States as well as the Silversword alliance, silver ...
Madiinae
Madieae is a Tribe (biology), tribe of flowering plants in the family Asteraceae. It is sometimes considered a subtribe of Heliantheae. Notable species include the tarweeds of the Western United States as well as the Silversword alliance, silver ...