Tetratheca is a genus of approximately 50 to 60 species of compact or diffuse shrubs endemic to Australia. It belongs to the family Elaeocarpaceae — the genus was formerly placed in the now-subsumed family Tremandraceae. Stems are typically terete, winged, or ridged and usually pubescent. The genus is best known for its delicate pink to purple bell-shaped flowers, which give many species their common name "pink-bells." Tetratheca occurs throughout extratropical Australia and has been recorded in every mainland state except the Northern Territory, spanning a wide range of habitats from heath to dry sclerophyll woodland. Well-known species include Tetratheca hirsuta (black-eyed susan), Tetratheca ciliata (pink-bells), Tetratheca thymifolia (thyme pink-bells), and Tetratheca pilosa (hairy pink-bells). Several species have restricted ranges and are of conservation concern.
Etymology
The genus name Tetratheca is derived from Greek, meaning "four-cased" or "four-chambered" (tetra = four; theca = case or capsule), a reference to the characteristic four-celled anthers of the flowers.
Distribution
Tetratheca is strictly endemic to Australia, occurring throughout extratropical regions of the continent. It is absent from the Northern Territory but has been recorded in all other mainland states, as well as Tasmania. The genus is most diverse in southern and southwestern Australia, with species found in heath, dry sclerophyll forest, and woodland habitats.
Taxonomy Notes
Tetratheca was traditionally placed in the family Tremandraceae, a small Australian endemic family. Molecular phylogenetic studies demonstrated that Tremandraceae is nested within Elaeocarpaceae, and it is now treated as a synonym of that family. The genus contains approximately 50–60 accepted species, with GBIF recording around 70 descendant taxa including synonyms.
