Oxera

Life-forms

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Asterids
Cladus: Lamiids
Ordo: Lamiales

Familia: Lamiaceae
Subfamilia: Ajugoideae
Genus: Oxera
Species: O. amicorum – O. baladica – O. balansae – O. brevicalyx – O. coriacea – O. coronata – O. crassifolia – O. glandulosa – O. gmelinoides – O. lehuntei – O. microcalyx – O. morieri – O. neriifolia – O. oreophila – O. palmatinervia – O. pulchella – O. robusta – O. rugosa – O. sessilifolia – O. splendida – O. subverticillata – O. sulfurea – O. vanuatuensis
Name

Oxera Labill., Sert. Austro-Caledon. 1: 23, t. 28 (1824)

Type species: Oxera pulchella Labill.

Synonyms

Homotypic
Oncoma Spreng., Syst. Veg. 4(2): 11 (1827)
Heterotypic
Maoutia Montrouz., Mem. Acad. Roy. Sci. Lyon, Sect. Lett. 10: 241 (1860)
Faradaya F.Muell., Fragm. 5: 21 (1865)
Schizopremna Baill., Hist. Pl. 11: 119 (1891).
Borya Montrouz. ex Beauvis., Ann. Soc. Bot. Lyon 26: 68 (1901).

References

Labillardière, J.J.H. de 1908. Sertum Austro-Caledonicum 23.
Govaerts, R. et al. 2020. Oxera in World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2020 Apr. 7. Reference page.
Tropicos.org 2014. Oxera. Missouri Botanical Garden. Published on the internet. Accessed: 2014 June 2.
International Plant Names Index. 2014. Oxera. Published online. Accessed: June 2 2014.

Oxera is a genus of flowering plants in the family Lamiaceae native to Vanuatu and New Caledonia in the western Pacific.[1]

Description

Species of Oxera show a variety of growth forms, including lianas, shrubs and trees.[2][3] The leaves are simple, and are petiolate (on short stalks), except in O. sessilifolia,[2][3] with entire or occasionally sinuate (wavy) edges.[3]

The inflorescences are loose thyrses of flowers, growing from leaf axils (axillary) or directly from the stem (cauliflory).[2][3] The flowers are large, conspicuous and bisexual; the calyx is actinomorphic (rotationally symmetrical), but the corolla is zygomorphic, sometimes strongly so.[2][3] Although some species have four stamens in each flower, they are usually reduced in number with two stamens, usually the posterior pair, forming staminodes instead.[2][3]
Distribution

Twenty of the twenty-one species are found on the island of Grande Terre (the main island of New Caledonia). Three species occur on the adjacent island of Île des Pins, two on Lifou and one on Maré in the Loyalty Islands, and two on Vanuatu (including one introduced species).[2]

Oxera vanuatuensis is only known from Vanuatu, where it is only known from cultivated specimens.[2] Villagers on Pentecost Island (and their descendants on Maewo call the tree harongmau, and propagate the species by planting seeds, transplanting seedlings or taking cuttings.[2] The plant is thought to treat illnesses caused by black magic, and profuse flowering from the trunk is thought to foretell a good harvest of yams.[2]
Species

Twenty-one species are recognised in the genus Oxera, in five informal species groups:[2][Note 1]

baladica group

Oxera baladica Vieill.
Oxera sessilifolia Dubard
Oxera subverticillata Vieill.
Oxera vanuatuensis de Kok – Vanuatu

robusta group

Oxera coriacea Dubard
Oxera coronata de Kok
Oxera palmatinervia Dubard
Oxera robusta Vieill.

pulchella group

Oxera balansae Dubard – Grande Terre, Île des Pins, Lifou EN[4]
Oxera brevicalyx (Moldenke) de Kok
Oxera crassifolia Virot LC[5]
Oxera morierei Vieill.
Oxera pulchella Labill. LC[6]

sulfurea group

Oxera gmelinoides S. Moore
Oxera microcalyx Guillaumin
Oxera rugosa Guillaumin
Oxera sulfurea Dubard – Grand Terre, Île des Pins, Lifou, Maré

macrocalyx group

Oxera glandulosa Vieill. – New Caledonia, Île des Pins
Oxera neriifolia (Montrouz.) Beauvis. [Note 2]
Oxera macrocalyx Dubard VU[8]
Oxera oreophila Guillaumin

Taxonomic history

The genus Oxera was erected by Jacques Labillardière in 1824, based on a single specimen that he had collected in New Caledonia.[2] The closest relative of Oxera is the genus Faradaya, and the two genera were once united as the tribe Oxereae.[2] Collectively, they are the sister group to a clade containing Clerodendrum and a number of segregate genera such as Kalaharia, Huxleya, Amasonia and Tetraclea.[9][10] Both genera are now treated as members of the subfamily Teucrioideae, following work published by Philip D. Cantino in 1992.[2]
Notes

All species are endemic to Grande Terre unless otherwise noted. Conservation statuses follow the IUCN Red List: EN = endangered species; VU = vulnerable species; LC = Least Concern.

Although "O. neriifolia" was treated as a nomen dubium by de Kok (1999),[2] it has since been accepted as the valid name for the species named "Oxera inodora" by de Kok.[7]

References

Kew World Checklist of Selected Plant Families
R. P. J. de Kok & D. J. Mabberley (1999). "A synopsis of Oxera Labill. (Labiatae)". Kew Bulletin. 54 (2): 265–300. doi:10.2307/4115808. JSTOR 4115808.
R. M. Harley; S. Atkins; A. L. Budantsev; P. D. Cantino; B. J. Conn; R. Grayer; M. M. Harley; R. de Kok; T. Krestovskaja; R. Morales; A. J. Paton; O. Ryding; T. Upson (2004). "Labiatae". In J. W. Kadereit (ed.). Flowering plants, Dicotyledons. Lamiales (except Acanthaceae including Avicenniaceae). The Families and Genera of Vascular Plants. 7. Springer. pp. 167–275. ISBN 978-3-540-40593-1.
V. Hecquet (2010). "Oxera balansae". IUCN Red List of Threatened Species. 2010: e.T177880A7475060. doi:10.2305/IUCN.UK.2010-4.RLTS.T177880A7475060.en. Retrieved 9 January 2018.
T. Jaffré; et al. (1998). "Oxera crassifolia". IUCN Red List of Threatened Species. 1998: e.T31149A9609607. doi:10.2305/IUCN.UK.1998.RLTS.T31149A9609607.en. Retrieved 9 January 2018.
V. Hecquet (2010). "Oxera pulchella". IUCN Red List of Threatened Species. 2010: e.T177875A7474332. doi:10.2305/IUCN.UK.2010-4.RLTS.T177875A7474332.en. Retrieved 9 January 2018.
D. J. Mabberley & R. P. J. de Kok (2004). "Labiatae". Hippocrateaceae, Labiatae, Vitaceae. Flore de la Nouvelle-Caledonie et Dependances. 25. Association de Botanique Tropicale. pp. 20–141. ISBN 978-2-85654-219-4.
T. Jaffré; et al. (1998). "Oxera macrocalyx". IUCN Red List of Threatened Species. 1998: e.T37427A10053658. doi:10.2305/IUCN.UK.1998.RLTS.T37427A10053658.en. Retrieved 9 January 2018.
Dorothy A. Steane, Rogier P. J. de Kok & Richard G. Olmstead (2010). "Phylogenetic relationships between Clerodendrum (Lamiaceae) and other Ajugoid genera inferred from nuclear and chloroplast DNA sequence data" (PDF). Molecular Phylogenetics and Evolution. 32 (1): 39–45. doi:10.1016/j.ympev.2003.11.011. PMID 15186795.
Yao-Wu Yuan, David J. Mabberley, Dorothy A. Steane & Richard G. Olmstead (2010). "Further disintegration and redefinition of Clerodendrum (Lamiaceae): implications for the understanding of the evolution of an intriguing breeding strategy" (PDF). Taxon. 59 (1): 125–133. doi:10.1002/tax.591013.