The false oranges are a group 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 ''

Citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...

'' genus, within the family,

Rutaceae The Rutaceae () is a family (biology), family, commonly known as the rueRUTACEAE
in Bo ...

. They 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 ...

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

. Though previously viewed as members of ''Citrus'', Swingle moved the false oranges into their own genus, ''Oxanthera''. He placed the genus within the Triphasiinae subtribe of

Citreae Citreae is one of the two tribes of the flowering plant family Rutaceae, subfamily Aurantioideae, the other being Clauseneae. Subtribes and genera Three sub-tribes are included: * Triphasiinae ** '' Luvunga'' Buch.-Ham. ex Wight & Arn. ** '' ...

based on the similar size of their fruit. However, subsequent

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis showed them to cluster in the Citrinae subtribe within the same clade as Swingle's genus '' Clymenia'' and the

Australian lime Australian limes are species of the plant genus ''Citrus'' that are native to Australia and Papua New Guinea. These species were formerly included in the genera ''Microcitrus'' and ''Eremocitrus''. They have been used as a food source by indigeno ...

s, as members of an enlarged monophyletic ''Citrus'', with the suggested relegation of the ''Oxanthera'' taxon as a ''Citrus''

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

. Bayer observed the presence of prominent pulp vesicles in the false oranges, and that their flowers had three to four times as many

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s as

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s in their flowers, are both traits similar to other ''Citrus''. The false orange lacks the thorns typical of the ''Citrus'' genus, a difference often seen on islands without indigenous herbivores. Species include:GRIN Species Records of ''Oxanthera''.
Germplasm Resources Information Network (GRIN).
University of California, Riverside. * '' Citrus oxanthera'' — orange flower oxanthera * '' Citrus neocaledonica'' — large-leaf oxanthera * '' Citrus undulata'' — wavy-leaf oxanthera * '' Oxanthera brevipes'' (status pending)

References

Aurantioideae Endemic flora of New Caledonia Taxonomy articles created by Polbot {{Rutaceae-stub