Acca Berg (1855), in the family Myrtaceae, contains 6 species in South America, including the pineapple guava, A. sellowiana (Berg) Burret, formerly called Feijoa sellowiana (Berg) Berg.

Description Trees to 3m, or shrubs. The leaves are opposite, ovate, silvery beneath, evergreen. The flowers are solitary in the leaf axils. Sepals 4, equal, reflexed, joined at the base only to form a tube; petals 4, pinkish and spotted inside, white and hairy outside, somewhat crinkled, reflexed. Stamens numerous, crimson, longer than the petals. Ovary inferior, with 2 fused carpels containing numerous ovules; style 1. Pollination is perhaps by hummingbirds or butterflies. The fruits are green or yellowish, fleshy, and juicy, and contain numerous seeds.

Key Recognition Features The silvery twigs and undersides of the rounded leaves, the 4 petals, and the long, red stamens.

Evolution and Relationships Psidium L., the guava, is related to Acca, but has 5 petals and sepals and in the cultivated species,
P. guayava L. from tropical America, much larger fruit with persistent green sepals. The relationships of the family Myrtaceae are discussed under Myrtus.

Ecology and Geography In scrub at low altitudes in southern Brazil, northern Argentina, Paraguay, and Uruguay.

Comment The fruits of Acca are are sometimes sold as feijoas. They are made into jam, and used to make a fizzy drink in southern Russia.