Neotropical Trigoniaceae

João Rodrigues Miguel & Elsie Franklin Guimarães

UNIGRANRIO & Jardim Botânico do Rio de Janeiro 


Trees up 35m in height and 50cm DAP, and erect shrubs or flexible vines, much branched, decumbent or scandent. Leaves simple, usually opposite, rarely spiral, two-ranked or fasciculate; sometimes glandular and/or hairy; the adaxial surface green, the abaxial white, gray, yellowish, rarely blue or green, with white indumentum; stipules deciduous or persistent. Inflorescences axillary or terminal, of simple or complex racemes, panicles, thyrses, monochacial cymes, 2- or 3-flowered; bracts and bracteoles linear or lanceolate, pilose or tomentose, +/- glandularFlowers pedicellate, cream or red, bisexual, zygomorphic, somewhat papilionoid; calyx of 5 green sepals, unequal, hairy, +/- glandular; corolla with 5 petals, banner petal "hunch-backed", +/- indumentum, usually with hairs only on the inner edge of the hump, two keel petals glabrous, and two spatulate petals with a tuft of hairs at the base; stamens 5-8, +/- 3-4 staminodes, anthers basifixed; ovary superior, syncarpous, tri-carpellate, 3(-1)-locular, ovules 1-numerous; style terminal, simple, stigma capitateFruit a 3-winged samara or septicidal capsule with one to many seeds, these surrounded by silky hairs and wind-dispersed.

Notes on delimitation

  • Based on molecular data the family is resolved as monophyletic and sister to the Dichapetalaceae in the order Malphigiales along with about 40 other families (APG III 2009).
  • Historically there has been considerable divergence of opinion as to the systematic position of the Trigoniaceae (Lleras 1978).  Previously it has been placed in order Polygalales (Erdtman 1952; Cronquist 1968) or order Rutales (Engler 1954, 1964), using mainly palynological and morphological evidence.

Distribution in the Neotropics

The family contains five genera and c. 31 species of which three genera and c. 29 species are represented in the Neotropics.

  • Isidodendron (monotypic) - Isidodendron tripterocarpum Fern.Alonso, Pérez-Zab. & Idarraga - inhabits the primary as well as secondary tropical moist forests and altered zones of Colombia (Fernández-Alonso, Pérez & Idarraga 2000).
  • Trigoniodendron (monotypic) - Trigoniodendron spiritusanctense E.F.Guim. & MiguelE.F. Guim. & Miguel - is frequent in the coastal rain forests of Brazil (Guimarães & Miguel 1987).
  • Trigonia Aubl. (c. 30 species) - some species inhabit primary forests, while others occur as pioneer species in degraded areas (Guimarães & Miquel 1985) throughout the Neotropics.

Distinguishing characters (always present)

Number of genera

3 genera:

Useful tips for generic identification

Key to genera of neotropical Trigoniaceae

1. Trees; leaves alternate … 2
1. Shrubs erect, scandent or vines; leaves opposite … Trigonia.

2. Fruit a globose capsule; flowers in axillary panicles, staminal ring ending in two glands; without staminodes ... Trigoniodendron
2. Fruit a samara; flowers in spikes; staminal ring devoid of glands; with 4 staminodes ...Isidodendron


  • Native

General notes

  • The hairs around the tiny seeds have been used for stuffing pillows and cushions.
  • Trigonia nivea Cambess. and Trigonia villosa Aubl. var. villosa are used as ornamentals.
  • Trigoni nivea has been used as medicine to cure kidney diseases in Paraty, Rio de Janeiro.
  • Trigonia microcarpa Sagot ex Warm. is used by indigenous people in the Amazon to increase uterine contractions in childbirth (in sched.).

Important literature

Cronquist, A. 1968.  The Evolution and Classification of Flowering Plants, pp. 274-277. Houghton Miffin, Boston.

Peterson, O.G. 1896.  Trigoniaceae. In: Engler, H.G.A. & Prantl, K.A.E. (eds.). Die Naturlichen Planzenfamilien, vol. 3, abt. 4, pp. 309-311, fig. 165-166. Wilhelm Engelmann, Leipzig .

Endlicher, S.L. 1841. Trigoniaceae. Enchiridion botanicum,  p. 570. W. Engelmann, Leipzig.

Erdtman, G. 1952.  Trigoniaceae. Pollen Morphology and Plant Taxonomy: Angiosperms, pp. 438-439. Almquist & Wiksell, Stockholm.

Fernández-Alonso, J.L., Pérez-Zabala, J.A. & Idarraga-Piedrahita, A. 2000. Isidodendron, un nuevo género neotropical de árboles de la familia Trigoniaceae. Revista da Academia colombiana de Ciencias Exatas, 34(92): 347-357.

Guimarães, E.F. & Miguel, J.R. 1985. Flora do Estado do Rio de Janeiro-família Trigoniaceae. Rodriguésia 37(63): 57-72, est.1-19c.

Guimarães, E.F. & Miguel, J.R. 1987. Contribuição ao conhecimento de Trigoniaceae Brasileiras VI. Trigoniodendron Guimarães & J. Miguel. n. gen. Rio de Janeiro, Brasil. Revista Brasileira de Biologia 47(4): 559-563, fig. 1-14.

Lleras, E. 1978. Trigoniaceae. Flora Neotropica. Monograph vol. 19, pp.1-73. + 19 figs. Organization for Flora Neotropica. New York Botanical Garden.

Miguel, J.R. & Guimarães, E.F. 2000. Trigoniaceae brasileiras XIII - Restabelecimento de um táxon e descrição de uma nova espécie. BRADEA 7(32): 197-200, 1 fig.

Warming, E. 1875. Trigoniaceae. In: Martius, C.F.P. von, Eichler, A.W. & Urban, I. (Eds.). Flora brasiliensis vol. 13, part.2, pp.118-144. t. 22-27. München, Wien, Leipzig.

How to cite

Miguel, J.R. & Guimarães, E.F. (2011). Neotropical Trigoniaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.