Neotropical Myrtaceae

Eve Lucas & Laura Jennings

Royal Botanic Gardens, Kew, UK. 

Description

Trees or woody shrubs; hairs simple or occasionally dibrachiate. Leaves opposite or sometimes sub-opposite.  Inflorescences very variable, can be terminal or usually axillary, solitary, dichasial, racemose, glomerulous or sometimes paniculate; perianth free in 4 to 5 parts or calyx calyptrate; stamens free, numerous; anthers versatile, dehiscing by longitudinal slits. Ovary generally inferior, occasionally semi-inferior, mostly 2, 3 or 4 (-10) locular; placentas axile, ovules radiating, sometimes pendulous; vascular supply to ovary trans-septal. Fruit indehiscent, fleshy; seeds usually numerous; embryo variable with cotyledons small and straight or elongate and curved, well developed and leafy or homogenous.

Distribution in the Neotropics

  • Acca O. Berg: Brazil to Peru and Uruguay.
  • Accara Landrum: Brazil.
  • Amomyrtella Kausel: Bolivia and Northern Argentina.
  • Amomyrtus (Burret) Legrand & Kausel: Chile, just into W. Argentina.
  • Blepharocalyx O. Berg: Brazil, Bolivia and Paraguay, Chile and Argentina.
  • Calycolpus O. Berg: Panama and Colombia, Venezuela to Peru and Trinidad, Guyana and Northern Brazil.
  • Calycorectes O. Berg: Cuba, Mexico south to Northern Argentina.
  • Calyptranthes Sw.: Florida and Caribbean, Mexico south to Northern Argentina.
  • Campomanesia Ruíz & Pavón: Brazil north to Venezuela and Trinidad, west to Colombia and Peru and south to Northern Argentina.
  • Chamguava Landrum: Mexico (Guerrero, Chiapas) to Honduras and Panama.
  • Eugenia L. Pantropical - in the Neotropics: Southern Florida and Caribbean and from Mexico to Argentina.
  • Gomidesia O. Berg: Brazil north to Venezuela, Guyana and the Caribbean to Hispaniola, south into Paraguay and Argentina.
  • Hexachlamys O. Berg: Southern Brazil and Paraguay to Bolivia and Northern Argentina.
  • Legrandia Kausel: Chile.
  • Luma A. Gray: Peru: Chile and Argentina.
  • Marlierea Cambess.: Trinidad-Tobago and Windward Is., Costa Rica to Colombia, Venezuela and the Guianas and Northern Brazil.
  • Mosiera Small: Southern Florida and Caribbean.
  • Myrceugenia O. Berg: Brazil to Argentina, Chile and Juan Fernandez Is.
  • Myrcia DC. ex Guillemin: Mexico and Caribbean south to Argentina.
  • Myrcianthes O. Berg: Florida and Caribbean, Mexico south to Chile, Argentina and Uruguay.
  • Myrciaria O. Berg: Guatemala and Belize south to Paraguay and Northern Argentina.
  • Myrrhinium Schott: Ecuador and Peru to Southern Brazil and Northern Argentina.
  • Myrteola O. Berg: From the Andes of Colombia south to Tierra del Fuego and Falkland Is.
  • Neomitranthes Legrand: SE. and Southern Brazil.
  • Pimenta Lindl.: Caribbean from Cuba to Trinidad, Mexico (Veracruz, Oaxaca) to Panama, Southern Bolivia, Southern and SE. Brazil.
  • Plinia L.: Caribbean: Costa Rica south through tropical South America to Argentina.
  • Psidium L.: Southern Mexico and Caribbean through tropical South America to Northern Argentina.
  • Siphoneugena O. Berg: Brazil north to Venezuela, the Guianas and Caribbean to Puerto Rico, south into Argentina.
  • Tepualia Griseb.: Chile.
  • Ugni Turcz.: Guatemala to Guyana (Mt. Roraima) and Chile, Juan Fernandez Is.

Distinguishing characters (always present)

  • No characters are ALWAYS present.

Other important characters

  • Opposite, simple leaves.
  • Pellucid gland dots on leaves and often other parts.
  • Leaves aromatic when crushed.
  • Intramarginal collecting vein present.
  • Inferior ovary.
  • No evident stipules.
  • Many (>100) stamens.

Key differences from similar families

The families listed below differ from Myrtaceae in the following characters:

Number of genera

  • 29 genera: Acca, Accara, Amomyrtella, Amomyrtus, Blepharocalyx, Calycolpus, Calycorectes, Calyptranthes, Campomanesia, Chamguava, Eugenia, Hexachlamys, Legrandia, Luma, Marlierea, Mosiera, Myrceugenia, Myrcia, Myrcianthes, Myrciaria, Myrrhinium, Myrteola, Neomitranthes, Pimenta, Plinia, Psidium, Siphoneugena, Tepualia, Ugni.

Useful tips for generic identification

  • Observe texture of seed testa.
  • Observe embryo shape and size.
  • Observe number of perianth parts.
  • Observe inflorescence architecture.
  • Note collection locality.

Notable genera and distinguishing features

  • Blepharocalyx: seed testa soft, embryo c-shaped, perianth 4-merous, parts free, arranged in a distinctive square upon ovary; inflorescences in complex branching dichasia of up to 35 flowers; single very variable and widely distributed species in Brazil, Venezuela and tropical Argentina.
  • Eugenia: seed testa soft; embryo homogenous resembling a bean; perianth mostly 4-merous, parts free, flowers often subtended by evident, conspicuous bracts; inflorescences solitary, in fascicles, spikes or racemes; widely distributed throughout the Neotropics, > 1,000 species.
  • Myrcia s.l.: seed testa soft; embryo membranous, plicate with long, distinct hypocotyl; perianth mostly 5-merous, calyx lobes free or fused, tearing open irregularly or circumscissile and falling as a calyptra; inflorescences in panicles; widely distributed throughout the Neotropics, > 700 species.
  • Myrceugenia: seed testa soft; embryo membranous, plicate with long, distinct hypocotyl; perianth mostly 4-merous, parts free (rarely circumscissile), valvate; inflorescences solitary or in dichasia; common in Brazil to Argentina: Chile and the Juan Fernandez Islands.
  • Pimenta: seed testa hard in all but one species, embryo c-shaped, perianth (4-)5-merous, parts free; inflorescences in complex branching dichasia of many flowers; extremely aromatic plant; common in central America, the Caribbean and southern Brazil.
  • Psidium: seed testa hard, embryo c-shaped, perianth mostly 4-merous, parts free to fused often tearing open irregualarly; inflorescences solitary or in panicles; common throughout South America.
  • Myrciaria, Neomitranthes, Plinia and Siphoneugena: seed testa soft; embryo homogenous resembling a bean; perianth mostly 4-merous, parts free or fused and falling as a circumscissile but open ring or tearing irregularly; inflorescences mostly sessile and in glomerules; central America, the Caribbean and particularly common in southern Brazil.

Status

  • All genera listed are native, and all but Eugenia are endemic to the Neotropics. 
  • Psidium (Guava), Eugenia uniflora (Pitanga) and Myrciaria cauliflora (Jaboticaba) are widely cultivated for fruit, jams and juices.
  • Syzygium jambos and various Eucalyptus species are introduced, cultivated (for fruit and timber/shade respectively) and are often naturalized.

Important literature

Govaerts, R., Sobral, M., Ashton, P., Barrie, F., Holst, B.K., Landrum, L.L., Matsumoto, K., Mazine, F.F., Nic Lughadha, E., Proença, C., Soares-Silva, L.H., Wilson, P.G. and Lucas, E. 2008. World Checklist of Myrtaceae. Kew Publishing: Royal Botanic Gardens, Kew.

Landrum, L.R. and Kawasaki, M.L. 1997. The genera of Myrtaceae in Brazil: an illustrated synoptic treatment and identification keys. Brittonia. 49: 508-536.

Lucas, E.J., Harris, S.A., Mazine, F.F., Belsham, S.R., Nic Lughadha, E.M., Telford, A., Gasson, P.E. and Chase, M.W. 2007. Suprageneric phylogenetics of Myrteae, the generically richest tribe in Myrtaceae (Myrtales). Taxon 56: 1105-1128.

McVaugh, R. 1956. Tropical American Myrtaceae, notes on generic concepts and descriptions of previously unrecognized species. Fieldiana, Bot. 29: 145-228.

McVaugh, R. 1963. Tropical American Myrtaceae, II, notes on generic concepts and descriptions of previously unrecognized species. Fieldiana 29: 393-532.

McVaugh, R. 1968. The genera of American Myrtaceae - an interim report. Taxon 17: 354-418.

How to cite

Lucas, E. & Jennings, L. (2009). Neotropical Myrtaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Myrtaceae.htm.