Acca sellowiana Berg. (Myrtaceae) is a fruit-bearing treelet or shrub native from the highlands of South Brazil. The plant is currently in the domestication process. Its fruit is sweet-acidified and can be consumed raw or be used for the preparation of juice and jam. Thus, information on the development, morphology and anatomy of the fruit is of great interest, and was featured as the objective of this study. The average fruit dimensions (ovary surrounded by the hypanthium) in the bloom stage were 0.6 cm in length and 0.4 cm in diameter, being ten times smaller than the ripe fruit. Longitudinally, three distinct regions were observed: a locular-, a sublocular- and a prolongation region. In a transverse cross-section in the middle of the fruit, three regions were delimited: 1) epidermis (peel) with simple unicellular trichomes. 2) parenchymatous region (flesh) rich in stone cells, isolated or aggregated in small groups of 2-3 cells; with eight radially distributed concentric periphloematic vascular bundles; and with many spherical glands near the epidermis. 3) inner region (pulp) with small cubic cells, organized in 3-4 layers around the locules, various containing druses. The four locules are separated by septa. The numerous ovules originate from axillary placentas, with two rows per locule. No nectaries were observed. As the fruit develops, groups of thin-walled cells appear in the intermediate region. These cells become very large and transform into stone cells. The placentas grow and occupy the whole space within the growing locules, as these locules grow bigger and seeds develop. Thus, the ripee fruit has a peripheral region of firm consistence and astringent taste, and a soft sweet core.
Pineapple guava; fruit anatomy; fruit growing
