Dendroseris is a subgenus of flowering plants in the genus Sonchus, family Asteraceae.

They have large leaves, either entire or lobed (pinnatifid), arranged in rosettes.

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 studies from 1996 onwards showed that Dendroseris was deeply embedded within the genus Sonchus with Thamnoseris as its sister.