Rollinia mucosa



Rollina mucosa

(Jacq.) Baill. 1916

pronounced: roll-IN-ee-uh mew-KOH-suh

(Annonaceae — the custard apple family family)

synonym — Rollina deliciosa

Saff. 1916

pronounced: roll-IN-ee-uh de-liss-ee-OH-suh

common names: biriba, wild sugar apple, Amazon custard apple

Rollinia is named for the French historian and professor Charles Rollin (1661 –1741); mucosa is from the Latin mucosus, silvery, and deliciosa from deliciosus, delicious.

This is a native to the lowlands of Brazil, now grown in many tropical countries of the world at altitudes of below 600 m and where there is more than 1300 mm of fairly well-distributed annual rainfall. It is a newcomer to Australia, and few trees (if any) have yet produced fruit here. The young tree photographed is growing in the garden of exotic fruit trees at Magnetic Island State School in Nelly Bay. It is a relative of the custard apple and the soursop.

It is a fast-growing tree that reaches 4 – 10 m in height, with a dense rounded canopy, and a spread of 4 – 5 m across. The simple light green leaves are elliptic to oblong-ovate in shape, alternate, leathery, between 10 and 30 cm long and up to 9 cm wide, on 5 – 10 mm petioles. The leaves are a smooth texture with the veins distinct on the under side, rather like the rib bones of a fish. The veins are a light yellow-green in colour. The leaves hang down from long slender branches, and give the tree an attractive feathery appearance.

The flowers fork in clusters on small fresh new branches, which shoot out of the sides of the long slender main branches. The flowers usually hang in clusters of 3 or 4, but only one at a time develops in each cluster ; they are hermaphrodite, borne on long pedicels, and exbibit protogynous dichogamy, i.e., there is a degree of overlap between male and female stages. Like avocadoes, this overlap is affected by environmental conditions, changing the degree of self-pollination possible. Below a relative humidity of 80%, pollination is compromised due to pollen and stigma desiccation. The flowers have 3 petals like the blades of a motor-car fan, and are slightly yellowy-green in colour. There is a small opening on the underside of each mature flower through which the pollinators, attracted by the sweet smell, crawl. Pollinators are thought to be beetles, thrips, and, to a lesser extent, flies.

The fruit is a syncarp berry consisting of many joined carpels of radial fruitlets, so the skin has many soft, rounded bumps, or more pronounced spines. It may be heart-shaped, or spherical-oblong, up to 20 cm long and weighing up to 3 kg. As the fruit matures, it changes colour from green to yellow. The succulent flesh is white to translucent. It has a slender opaque core (receptacle) and many black seeds, about 1 – 1.5 cm long, that are easily removed. The edible flesh is about half of the fruit.

It is usually eaten fresh, but can be used to make milkshakes, jams, jellies, chutneys and pickles. The flesh does oxidze very rapidly once the fruit is cut.

Trees grown from seedlings have a juvelile period of between 3 and 4 years. Fruit yield will increase until the tree is about 15 years old, when a well-managed tree will produce up to 150 fruits. The fruits should be picked when they are firm, but starting to turn yellow, and secateurs should be used, rather than just pulling off the fruits. They will then take up to about a week to ripen. Fully ripe fruits will develop black ends to their spines. Fruits are very fragile, and need to be handled with great care to avoid any damage. Damaged portions will rapidly darken, and the fruit will have very mushy flesh and will quickly ferment.

The wood of this tree is durable, and is used in boat construction. Also, young trees are used as the main bow of the berimbau, an Afro-Brazilian musical instrument.

Photograph of fruit by Rovin Laudin Alba Torres, via Wikipedia Commons, used temporarily until the local tree fruits.
Photographed in Nelly Bay 2018
Page last updated 24th March 2019