''Tetratheca'' is a

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 ...

of around 50 to 60 species of shrubs

endemic Endemism is the state of a species being found 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 found elsew ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It is classified in the

botanical Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Elaeocarpaceae Elaeaocarpaceae is a family of flowering plants. The family contains approximately 615 species of trees and shrubs in 12 genera."Elaeocarpaceae" In: Klaus Kubitzki (ed.). ''The Families and Genera of Vascular Plants'' vol. VI. Springer-Verlag: Be ...

, now known to encompass the family

Tremandraceae Tremandraceae R.Br. ex DC. is the name of a defunct family of flowering plants. It contained three genera: '' Platytheca'', '' Tetratheca'', and '' Tremandra''. In 2006, a molecular phylogenetic study showed that Tremandraceae is embedded in El ...

, which the genus originally belonged to. It occurs throughout extratropical Australia, and has been recorded in every mainland state except the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

Origin and evolution

The origin of the genus is thought to be south-western Western Australia, radiating eastward. The distribution of ''Tetratheca'' is mainly across the temperate southern part of the continent. Most species are localised endemics and are highly disjunct from each other. Very few are widespread across Australia; none occurs in the

Nullarbor Plain The Nullarbor Plain ( ; Latin: feminine of , 'no', and , 'tree') is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its ...

and only seven are found on both the western and the south-eastern sides. (McPherson, 2008). The formation of the Nullarbor is thought to have created a barrier to dispersal between the east and west. It is estimated that the family Elaeocarpaceae is 120 million years old and Tetratheca estimated to be around 37 to 39 million years old, with major diversification over the Miocene and evolving much faster than their relatives, many of which are rainforest species. This coincides with the rapid radiation and diversification of other sclerophyllous groups.

Species

Species include: *'' Tetratheca affinis'' Endl. *'' Tetratheca aphylla'' F.Muell. - Bungalbin tetratheca *'' Tetratheca bauerifolia'' F.Muell. ex Schuch. - heath pink-bells *'' Tetratheca ciliata'' Lindl. - pink-bells *'' Tetratheca confertifolia'' Steetz *'' Tetratheca decora'' Joy Thomps. *'' Tetratheca deltoidea'' Joy Thomps. *'' Tetratheca efoliata'' F.Muell. *'' Tetratheca elliptica'' Joy Thomps. *'' Tetratheca ericifolia'' Sm. *'' Tetratheca erubescens'' J.P.Bull *'' Tetratheca exasperata'' R.Butcher *'' Tetratheca fasciculata'' Joy Thomps. - Cronin's tetratheca *'' Tetratheca filiformis'' Benth. *''

Tetratheca glandulosa ''Tetratheca glandulosa'' is a spreading shrub in the family Elaeocarpaceae. It is endemic to New South Wales. Description Its leaves are alternate or opposite or rarely in whorls of three or four. They are linear and 3–20 mm long by 1–2 m ...

'' Sm. *'' Tetratheca gunnii'' Hook.f. - shy susan *'' Tetratheca halmaturina'' J.M.Black - curly pink-bells *'' Tetratheca harperi'' F.Muell. - Jackson tetratheca *'' Tetratheca hirsuta'' Lindl. - black-eyed susan *'' Tetratheca hispidissima'' Steetz *'' Tetratheca insularis'' Joy Thomps. *'' Tetratheca juncea'' Sm. *'' Tetratheca labillardierei'' Joy Thomps. *'' Tetratheca neglecta'' Joy Thomps. *'' Tetratheca nephelioides'' R.Butcher *'' Tetratheca nuda'' Lindl. *'' Tetratheca parvifolia'' Joy Thomps. *'' Tetratheca paucifolia'' Joy Thomps. *'' Tetratheca paynterae'' Alford *'' Tetratheca phoenix'' R.Butcher *'' Tetratheca pilata'' R.Butcher *'' Tetratheca pilifera'' Lindl. *'' Tetratheca pilosa'' Labill. - hairy pink-bells *'' Tetratheca procumbens'' Hook.f. - mountain pink-bells *'' Tetratheca pubescens'' Turcz. *'' Tetratheca remota'' Joy Thomps. *'' Tetratheca retrorsa'' Joy Thomps. *'' Tetratheca rubioides'' A.Cunn. *'' Tetratheca rupicola'' Joy Thomps. *'' Tetratheca setigera'' Endl. *'' Tetratheca shiressii'' Blakely *'' Tetratheca similis'' Joy Thomps. *'' Tetratheca stenocarpa'' J.H.Willis - long pink-bells *'' Tetratheca subaphylla'' Benth. - leafless pink-bells *'' Tetratheca thymifolia'' Sm. - black-eyed susan, thyme pink-bells *'' Tetratheca virgata'' Steetz

References

Oxalidales of Australia Elaeocarpaceae genera {{Australia-rosid-stub