1. Oxalidaceae R.Br.

    1. This family is accepted.


Oxalidaceae, Christine H. S. Kabuye  (East African Herbarium). Flora of Tropical East Africa. 1971

Annual or perennial herbs or subshrubs, rarely shrubs or trees
Leaves basically alternate, exstipulate or stipulate, simple or, more usually, digitately or pinnately compound
Flowers in axillary cymes or in pseudumbels or solitary, regular, hermaphrodite
Sepals 5, free, with imbricate aestivation
Petals 5, free or somewhat adherent near the base
Stamens 10(15), 2(3)-seriate; filaments fused below to form a tube with alternate short and long stamens; anthers 2-thecous, versatile, opening inwards
Ovary superior, 5-locular; styles 5, rarely 1; stigmas capitate, entire, bifid or laciniate; ovules 1–many in each locule; placentation axile
Fruit a capsule dehiscing loculicidally, or a berry
Seeds with the endosperm fleshy or absent; embryo straight

Oxalidaceae, A. W. Exell. Flora Zambesiaca 2:1. 1963

Annual or perennial herbs, rarely trees or shrubs or shrublets
Leaves alternate, exstipulate (but sometimes with stipule-like expansions at the base of the petiole), digitately or pinnately 1-? -foliolate
Flowers in axillary cymes or in pseudumbels or solitary, actinomorphic or nearly so, bisexual, 5-merous, often heterostylous, sometimes cleistogamous and reduced
Sepals 5, free, imbricate (rarely valvate)
Petals 5, contorted or imbricate, free or slightly connate at the base
Stamens 10 (15), 2 (3)-seriate; anthers versatile, 2-thecous; filaments ± connate at the base
Ovary superior, 5-locular; loculi 1-?-ovulate, with axile placentation; styles 5 (rarely 1), free; stigmas capitate, entire
Fruit a loculicidally dehiscent capsule (rarely baccate)
Endosperm fleshy or absent

Fiaschi, P. (2010). Neotropical Oxalidaceae.


Shrubs or herbs with bulb -like tubers, bulbs or fleshy rhizomes. Leaves alternate and spiraled, sometimes forming a basal rosette , usually trifoliolate (sometimes unifoliolate), pinnately or palmately compound , sometimes unifoliolate or reduced and replaced by phyllodes; venation palmate or pinnate , stipules usually lacking. Inflorescences axillary , cymose (sometimes forming an umbel or capitulum ), the pedicels articulated. Flowers perfect, hypogynous, radial, pentamerous, sometimes showing trimorphic heterostyly; sepals 5, distinct; petals 5, distinct or very slightly connate , usually convolute, basally clawed, often brightly coloured; stamens 10, basally connate , outer filaments shorter than inner, basis sometimes nectar -producing (or nectar produced in antepetalous glands ); anthers longitudinally dehiscent ; pollen tricolpate or tricolporate; ovary superior , with 5 free or connate carpels, each locule with (1)2-several ovules, placentation axile ; styles 5, distinct; stigmas capitate or punctate , sometimes bilobed. Fruit a loculicidal capsule , often lobed or angled; seeds with a mucilaginous testa, which elastically turns inside out ejecting seeds.

Distribution in the Neotropics
  • Biophytum DC. - pantropical genus with about 30 neotropical species, in rain forests or disturbed areas from sea level to about 2,000 m alt.
  • Oxalis L. - cosmopolitan genus with about 500 spp., approximately 185 of which are found in the Neotropics.
Notable genera and distinguishing features
  • Biophytum species have imparipinnate leaves clustered at the branch apices, and the terminalleaflet is reduced to a bristle-like mucro.
  • Oxalis usually has trifoliolate leaves, either pinnate or palmately arranged.  
Distinguishing characters (always present)
  • Compound (or unifoliolate) leaves.
  • Determinate inflorescences.
  • Perfect, radial, hypogenous flowers.
  • Ten stamens with two different lengths.
  • Fruits loculicidal capsules.
General Description
  • Averrhoa L. has two cultivated species in the Neotropics: A. bilimbi L. and A. carambola L.
  • Biophytum DC. has about 30 native and one cultivated species (B. sensitivum) in the Neotropics.
  • Oxalis L. has about 185 native species in the Neotropics.
  • Oxaliscorniculata L. and O. pes-caprae L. are naturalized, and O. tetraphylla (L.) DC. is cultivated.
General notes
  • The Tropical Andean genus Hypseocharis L., formerly assigned to Oxalidaceae, has been currently placed in the Geraniaceae.
  • Morphological features that support Hypseocharis as part of the Geraniaceae, instead of Oxalidaceae, include the antesepalous position of necariferous glands, presence of 15 stamens in two whorls, adnation of sepal, petal and stamen traces (Devi, 1991), the single style (Judd et al., 2002) and the pollen morphology (Erdtman, 1952).
Number of genera
  • Two native genera (Biophytum and Oxalis) and one inroduced (Averrhoa L.).
Notes on delimitation
  • This family has traditionally been placed close to the Geraniaceae in the order Geraniales. The current placement of the Oxalidaceae is together with the Connaraceae, Cunoniaceae, Elaeocarpaceae and a few smaller families in the order Oxalidales (APG III, 2009). See also 'General notes' below.
Important literature

Aymard, G. & Berry, P.E. 2003. Three New Species of Biophytum (Oxalidaceae) from the Venezuelan Guayana. Novon 13 (2): 174-179.

Burger, W. 1991. Flora Costaricensis: Oxalidaceae. Fieldiana, Bot. 28, p. 2-16.

Devi, D.R. 1991. Floral anatomy of Hypseocharis (Oxalidaceae) with a discussion on its systematic position. Pl. Syst. Evol. 177: 161-164.

Erdtman, G. 1952. Pollen morphology and plant taxonomy - angiosperms. Almqvist & Wiksell, Stockholm.

Fiaschi, P. & Conceição, A.A. 2005. Oxalidaceae. In: M.G.L. Wanderley, G.J. Shepherd, T.S. Melhem & A.M. Giulietti (eds) Flora Fanerogâmica do Estado de São Paulo. São Paulo, vol. 4, p. 301-315.

Heibl, C. 2005. Studies on the systematics, evolution, and biogeography of Oxalis sections Caesiae, Carnosae, and Giganteae, endemic to the Atacama Desert of northern Chile. Master thesis. Ludwig-Maximilians-Universität, München.

Judd, W.S., Campbell, C.S., Kellogg, E.A., Stevens, P.F. & Donoghue, M.J. 2002. Plant Systematics: a phylogenetic approach. Sinauer Associates, Sunderland.

Knuth, R. 1930. Oxalidaceae. In: A.G. Engler (ed.) Das Pflanzenreich. Wilheem Englelmann. Leipzig, vol. 6, pt. 130, p. 1-481.

Lourteig, A. 1980. Flora of Panama: Oxalidaceae. Ann. Missouri Bot. Gard. 67: 823-850.

Lourteig, A. 1983. Oxalidáceas. In: R. Reitz (ed.) Flora Ilustrada Catarinense. Herbário Barbosa Rodrigues, Itajaí.

Lourteig, A. 1994. Oxalis L. subgénero Thamnoxys (Endl.) Reiche emend. Lourteig. Bradea 7 (1): 1-197.

Lourteig, A. Oxalis L. subgéneros Monoxalis (Small) Lourt., Oxalis y Trifidus Lourt. Bradea 7 (2): 1-629.

Progel, A. 1877. Oxalidaceae. In: C.F.P. Martius & A.G. Eichler (eds) Flora brasiliensis. Typographia regia, Monarhii, vol. 12, pt. 2, p. 473-519.


Oxalidaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:1. 1954

Herbaceous or suffrutescent, rarely arborescent
Leaves alternate, digitately or pinnately compound, sometimes simple by suppression of the leaflets; leaflets spirally coiled when young, usually closing at night; stipules absent
Flowers hermaphrodite, actinomorphic, sometimes of two kinds, some perfect and others minute and apetalous, solitary or subumbellate, rarely racemose or cymose
Calyx 5-fid or 5-partite, imbricate
Petals 5, shortly clawed, free or shortly connate at the base, contorted
Stamens 10, hypogynous, connate at the base, sometimes 5 of them without anthers; anthers 2-celled, opening lengthwise
Ovary 5-celled, superior; styles 5, free, persistent; stigmas capitate or shortly divided; ovules 1 or more, axile
Fruit mostly a capsule
Seeds often with an elastic epidermis; endosperm fleshy, copious; embryo straight


Oxalidaceae R.Br. appears in other Kew resources:

First published in Narr. Exped. Zaire 433. 1818 [5 Mar 1818] (1818)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385


Flora Zambesiaca
Flora Zambesiaca

Flora of Tropical East Africa
Flora of Tropical East Africa

Flora of West Tropical Africa
Flora of West Tropical Africa

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.