''Sonchus'' subg. ''Dendroseris'' is a subgenus of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s 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 w ...

'', family

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 ...

. It was formerly treated as the genus ''Dendroseris'', with one species sometimes placed in ''Thamnoseris''. All the species placed in the subgenus are

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to either the

Juan Fernández Islands The Juan Fernández Islands () are a sparsely inhabited series of islands in the South Pacific Ocean, reliant on tourism and fishing. Situated off the coast of Chile, they are composed of three main volcanic islands: Robinson Crusoe Island, R ...

or the

Desventuradas Islands The Desventuradas Islands (, , "Unfortunate Islands" or ''Islas de los Desventurados'', "Islands of the Unfortunate Ones") is a group of four small oceanic islands located off the coast of Chile, northwest of Santiago in the Pacific Ocean. They a ...

in the

South Pacific The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

, both part of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

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 Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

), arranged in rosettes. The base of the

flower head A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...

(the receptacle) 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 fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

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 David Don (21 December 1799 – 15 December 1841) was a Scottish botanist. Biography David Don was born on 21 December 1799 at Doo Hillock, Forfar, Angus, Scotland to Caroline Clementina Stuart, and her husband George Don of Forfar. His olde ...

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 Federico Philippi or Friedrich Heinrich Eunom Philippi (16 December 1838 – 16 January 1910) was a German zoologist and botanist active in Chile. He was the youngest son of the famed naturalist Rodolfo Amando Philippi and Caroline Krumwiede. He wa ...

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'': File:Dendroseris pruinata, Conservatoire botanique national de Brest 02.jpg, '' Sonchus pruinatus'' in cultivation File:Dendroseris macrophylla - Curtis's Bot. Mag., tab 6353jpg.jpg, '' Sonchus splendens''

Distribution

All species are

to the

with the exception of ''Sonchus laceratus'', which is endemic to the

References

Dendroseris Taxonomy articles created by Polbot Plant subgenera {{Cichorieae-stub