Acca is a small genus of South American trees belonging to the myrtle family. The best-known species is Acca sellowiana, which is native to southern Brazil and Uruguay but is widely cultivated in subtropical and mild temperate regions of the world as it is tolerant of occasional frosts and snow. There is some evidence from the species’ genetic variability that feijoa originated in the Brazilian highlands above 29 degrees South and is now expanding southwards into the lower altitudes of colder Uruguay.
Feijoa trees have attractive leaves that are dark, glossy green above and silvery-white below. The flowers have pink petals and stiff, thick, dark red stamens. These stamens are so distinctive, that the first name given to this genus by its author, the German botanist Otto Karl Berg (1815-1866), was Orthostemon, which means ‘erect stamens’. When Berg discovered that this Latin name had already been used for another genus, he changed it to Feijoa. The Latin name Feijoa commemorates the Brazilian naturalist João da Silva Feijó (1760-1824), who was a member of the Royal Academy of Sciences of Lisbon. Although Feijoa is now included within the genus Acca, the original Latin name has become the plant’s common name. Other common names for feijoa are pineapple guava or, in Brazil, mountain guava.
Feijoa is bird-pollinated, but is distinctive from other bird-pollinated species. Most flowers that are pollinated by birds produce nectar; feijoa flowers produce no nectar, but have sweet, juicy petals that curl and resemble pale pink berries when the flower opens. The flowers are pollinated by fruit-eating and omnivorous birds that devour the petals and feed them to nestlings, and not by the usual hummingbirds or sunbirds. This was discovered in 1866 by the German-Brazilian naturalist Johann Müller (1821-1897) with the help of his five-year old grandson, who was ordered to watch the trees. People now eat the petals or add them to fruit salads – the taste is said to resemble strawberries.
A few months after flowering, feijoa produces refreshing, edible fruits that are elliptic, dark green outside and cream-coloured inside. They resemble guavas, to which they are related, in size, texture and seediness. Feijoa is popular in family orchards in southern Brazil. Since feijoa is incapable of self-pollinating, several cultivated trees must be planted together, or placed close to wild trees, for fruits to form. Even within the same tree, fruit size varies greatly from year to year.
Berg, OK 1859. Supplementum Myrtacearum. In Martius, CFP and Eichler, AG (eds) Flora Brasiliensis. Volume 14 (1) . Fleischer, pp. 529-656.
Nadra, MG et al. 2018. Evolution of pollination by frugivorous birds in Neotropical Myrtaceae. PeerJ 6: e5426
Sazima, I and Sazima, M 2007. Petiscos florais: pétalas de Acca sellowiana (Myrtaceae) como fonte alimentar para aves em área urbana no Sul do Brasil. Biota Neotropica 7: 307-312.