''Sonchus'' subg. ''Dendroseris'' is a subgenus of
flowering plants in the genus ''
Sonchus
''Sonchus'' is a genus of flowering plants in the tribe Cichorieae within the family Asteraceae and are commonly known as sow thistles (less commonly hare thistles or hare lettuces). Sowthistles are annual, biennial or perennial herbs, with or ...
'', family
Asteraceae. It was formerly treated as the genus ''Dendroseris'', with one species sometimes placed in ''Thamnoseris''. All the species placed in the subgenus are
endemic to either the
Juan Fernández Islands or the
Desventuradas Islands in the
South Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
, both part of
Chile.
[
]
Description
Species of ''Sonchus'' subg. ''Dendroseris'' have an unusual growth habit for members of the genus. They are shrubs or trees, some up to high. The shrubby species are succulent, the tree-like species are either unbranched or weakly branched. They have large leaves, either entire or lobed ( pinnatifid), arranged in rosettes. The base of the flower head (the receptacle
Receptacle may refer to:
Biology
* Receptacle (botany), a plant anatomical part
* Seminal receptacle, a sperm storage site in some insects
Electrical engineering
* Automobile auxiliary power outlet, formerly known as ''cigarette lighter recep ...
) does not have scales. The flowers are white to orange in colour. The achene
An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...
s are usually flattened and irregularly shaped. The pappus is made up of relatively few, stiff and non-feathered hairs. The species are tetraploids, with the base chromosome number ''x''=9.
Taxonomy
The genus ''Dendroseris'' was first established by David Don in 1832 with the species ''D. macrophylla''. Further species from the Juan Fernández Islands were later added to the group, sometimes being placed in other genera (''Rea'', ''Phoenicoseris'', and ''Hesperoseris''). Federico Philippi created the monotypic genus ''Thamnoseris'' for a species endemic to the Desventuradas Islands, ''Th. lacerata''. Molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
studies from 1996 onwards showed that ''Dendroseris'' was deeply embedded within the genus ''Sonchus'' with ''Thamnoseris'' as its sister. Accordingly, all species were transferred to ''Sonchus'', and placed in subgenus ''Dendroseris''.[
]
Species
All the species formerly placed in the genera ''Dendroseris'' and ''Thamnoseris'' have been transferred to ''Sonchus'' subg. ''Dendroseris'':Sonchus pruinatus
''Sonchus pruinatus'', synonym
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''co ...
'' in cultivation
File:Dendroseris macrophylla - Curtis's Bot. Mag., tab 6353jpg.jpg, ''Sonchus splendens
''Sonchus splendens'', synonym ''Dendroseris macrophylla'', is a species of flowering plant in the family Asteraceae. It is endemic to the Juan Fernández Islands of Chile. It is threatened by habitat loss.
Taxonomy
The species was first ...
''
Distribution
All species are endemic to the Juan Fernández Islands with the exception of ''Sonchus laceratus'', which is endemic to the Desventuradas Islands.[
]
References
Dendroseris
Taxonomy articles created by Polbot
Plant subgenera
{{Cichorieae-stub