The mountain soursop is a fruit-producing plant native to some areas in South and Central America, with the scientific name Annona montana. The fruit of mountain soursop is edible but many people consider it tasteless, although some varieties produce better quality fruits. It has bitter or sour flesh but it is otherwise similar to the normal soursop, better known as the guanabana.
The mountain soursop plant is part of the Annonaceae family and is valuable for its fibrous but edible fruits, which are important as food and for their medical benefits.
Also known as the mountain custard apple, the tree is evergreen and small in size, with a maximum height of about 30 feet. The leaves are attractive, with a glossy finish. The fruit is spherical, with prickles on the yellow skin. The flesh is fragrant but with a fibrous texture, similar in taste to a soursop. Seeds are light brown and are located in the pulp.
Mountain soursop fruit has a number of names: wild custard apple, mountain soursop or Annona montana. Mountain soursop is related not only to the soursop (A. muricata), but also to the cherimoya (A. cherimola) and pawpaw (Asimina triloba). It can be found in Central America, areas of the Amazon Basin, as well as some Caribbean islands. The native range of the tree starts from sea level up to altitudes of about 650 m. Unlike most tropical fruit trees, it is very resilient and can tolerate many different soil types and even survive short periods of frost. Despite the mediocre fruit, it is sometimes cultivated due to its adaptability.
The mountain soursop is evergreen, with pretty glossy leaves and an attractive crown. The mountain soursop tree starts producing fruits after two or three years, with a constant yield. The fruits are round, with a diameter of about 15 cm. The skin is dark green, with prickles and brown hairs on its surface. The yellow flesh has an interesting aroma but is fibrous, with a taste between sour and bitter. Numerous plump brown seeds can be found in the flesh. It is not cultivated widely because the fruit is not as tasty as a normal soursop, with limited commercial value.
Leaves, bark, roots, seeds.
The mountain soursop plant is known to kill cancer cells due to compounds found mostly in the bark and the leaves. Leaves can be prepared as a decoction that has sedative properties and calms the nerves, which promotes peaceful sleep if consumed before going to bed. Fevers and head pain can be relieved using the plant's leaves.
Natives of South America and the Caribbean Islands make heavy use of the mountain soursop and the graviola (or the normal soursop) in their traditional medicine. Inflammation, cough, asthma, bronchitis, internal parasites, high blood pressure and diabetes can be treated with several parts of the tree, including the leaves, roots, bark, fruits and seeds. According to at least one modern study, the plant can kill cancer cells that resist most forms of treatment. It is also known as a sedative and anti-depressive. Infusions from the leaves are known as painkillers for women during pregnancy. The exact compounds that provide these health benefits have not been identified yet but probably the alkaloid compounds named acetogenins are responsible. However, other substances like quinolones, annopentocins or annomuricin might be the active elements.
Like most related members in the Annonaceae family, the mountain soursop can also be dangerous due to a content of annonacin and other neurotoxic alkaloids. Even if these are found only in small amounts, the plant should be consumed with care. Frequent consumption or large quantities can lead to severe neurological problems such as atypical Parkinsonism.
The mountain soursop fruit can be consumed fresh immediately after harvesting. The aroma is strong but the taste is acid and bitter at the same time.
Mountain soursop is often compared with the normal soursop fruit, which has a superior taste. However, the two fruits are eaten in the same way: raw, prepared as drinks with milk or as an ingredient in ice cream. The immature fruits can be eaten as green vegetables in soup, before the seeds become hard.
The flesh of the mountain soursop fruit is yellow, similar to the color of a lemon. It is almost perfectly spherical, with the green skin turning slightly yellow when ripe. The resilience of the tree makes it very useful as rootstock, especially in cool climates, even if the fruit is inferior in quality compared to a soursop. It is easy to distinguish from it because the skin doesn't have as many spikes. Mountain soursop can survive in cooler climates and can even tolerate minor frost, as well as poor soils and severe drought. It needs about 2 or 3 years to start producing fruits. Sunny or partially shaded locations are the best choices.
Seeds are viable for propagation but have to be handled with care. They are only useful for a brief period after harvesting, since they can't be dried. Cool temperature makes the seeds unviable. Once established, the tree survives short periods of frost, down to -2 degrees Celsius. The tree likes clay sandy soil but also tolerates dry one, in both full sun and partial shade.
The mountain soursop is native to wet tropical areas and has a range extending from sea level to 2000 meters high in the mountains. It enjoys temperate areas, with an annual daytime average between 14 and 32 degrees Celsius. Young plants can't survive during frost but mature trees withstand brief periods at -2 to -4 degrees Celsius without significant damage.
For best results, it requires sandy loam with a pH between 5.5 and 6.5, but it can grow in any type of fertile soil with good drainage. Locations with full sun are the best. The level of annual rainfall should be 640 to 4,000 mm, but it enjoys levels in the range 900 - 1,700 mm.
Compared to its close relative A. Muricata, the mountain soursop is a lot more resistant to cold weather, which extends its range to higher elevations. In some areas, the first fruit production happens after 2 or 3 years, while in others it takes 5 to 6 years. In the right conditions, the tree produces both fruits and flowers during the entire year.
Due to the hard seed shell, common to most related plants, scarification usually increased the speed of germination if performed before sowing. The best way to achieve this is to place the seeds for a day or half a day in warm water. The water should be near boiling point initially, but not boiling since it will kill the seeds. At the end, the seeds absorb water and become bloated. Sometimes, a small dent in the coat is required, without touching the core, followed by a new period of soaking in warm water. The tree can also be propagated using cuttings, which should be semi-ripe.