Plants & People: The Intersection of Botany and Human Experience

Annona cherimola: The most delicious fruit known to man

Nomenclatural History
Annonaceae cherimola Miller or otherwise known by the common names of chirimoya, cherimola, or cherimoya.The common name of cherimoya originated from the Quechua word chirimuya which means “cold seeds”. This is because the tree itself only grows at high altitudes with colder temperatures and the seeds will only germinate in those conditions (Morton 1987). However, the creamy texture of the flesh and aroma also give it its secondary common name of the “custard apple”.

Evolutionary History
Consectetur lorem Annona cherimola Miller is a part of the larger Annonaceae family, which contains about 130 genera and 2400 species as well as being one of the oldest family among the flowering plants with an ancestry of roughly 95 million years. Among the genus Annona, which diverged 25 million years ago, there are around 175 species. Some common species under this genus include soursop, sugar apple, and atemoya which is a hybrid cross between cherimoya and sugar apple. Molecular data suggests that the A. cherimoya and the A. squamosa (sugar apple) are the closest relatives amongst the fruiting species (Rare Fruit Club, 2021).

Ecology and Life History
The cherimoya tree is a subtropical or mild-temperate tree that is sensitive to climate. It requires long days and is typically grown in high elevations between 4,000 and 8,000 ft where the temperature ranges from 62.° and 77°F (Morton, 1987). Any temperatures lower than 26°F can severely kill or injure the mature tree. It also prefers drier and non-windy climates for proper pollination. The seeds, if properly stored, are viable for several years. To properly plant, soak in water for 1 to 4 days and discard those that float. Plant directly in the soil and will germinate in 3 to 5 weeks (Morton, 1987). Once the plants are 3 to 4 inches high they are transplanted to nursery pots and within a year to two they bud and are grafted, growing up to 3 to 4ft  (Morton, 1987). To properly grow the tree, it is recommended to interplant with maize or potatoes to provide some organic material to the soil it grows in. The tree goes dormant during the winter for around 4 months and once the dormancy period is over, leafbuds begin to appear and yield fruits around 3.5 to 5 years old. Production ramps up during the 5th to 10th year where there is an expected yield of 25 fruits per tree. The ideal time to pick the fruits is when its full grown but firm as ripening is best off the tree. There should be a slight yellow-greenish hint on the skin. In Bolivia, they shake the fruit to listen to the sounds of loose seeds to judge if its ready to be picked. Once picked, the fruit should be stored at room temperature and will soften and be ready to eat in 3 to 4 days.

Vegetative Morphology
The tree mostly remains green and functional through different seasons, it is a relatively fast-growing tree with low-branched and spreading tree. The heigh can range from 16 to 30 ft tall. The mature branches are woody and sappy. The leaves are leathery and are approximately 2 to 9.8 inches long and 1.2 to 3.9 inches wide. They have an elliptic shape, and they are more rounded near the leaf stalk with more pointed ends. The leaves are single and they alternate. They usually have a darker green color and they are slightly hairy on the upper surface.

Reproductive Morphology
The flowers are pale green and they are about 1.2 inches long. They are dichogamous and borne in either solitary or groups of 2-3 on short stalks. Dichogamous means that the flowers have the stamen and pistil mature at different stages, which prevents self pollination. The flowers themselves have three oblong petals that have a slightly pink and white interior and have a green or brown exterior.  They are fragrant and have a strong fruity odor. 
The fruit is edible and the appearance is conical, almost heart-shaped. The interesting skin of the fruit is formed from the fusion of the carpels which results in the bumpy texture. They are usually 4 to 8 inches long and 4 inches in width. They weigh around 18 ounces. The fruit can be easily broken or cut open. The inside is white, juicy and creamy with a pleasing aroma. The black bean like seeds are approximately ½ to ¾ in long and scattered throughout the flesh once opened.

Historical Accounts
There is a historical account that the seeds of the cherimoya were sent by P. Bernabe Cobo from Guatemala in 1629 and thirteen years after the cherimoya fruits and trees were found in markets and cultivation in Lima. Cobo also sent the seeds to Mexico in 1629, where, now, it thrives in the higher elevations. In 1757, it was introduced to Spain as a dooryard tree but in the 1940s, the cherimoya tree became a staple and replacement for the orange trees that were wiped out due a disease. Today, Spain is one of the biggest producers of cherimoya. In 1871, the seeds from Mexico were brought over to California and planted. 9,000 trees were plants in 1936 but were killed off by too cold of a climate in 1937 and only small orchards remain. California remains the only state in the United States that can successfully cultivate cherimoya and bear fruits (Morton, 1987). Mark Twain also writes that the cherimoya is “the most delicious fruit known to men”.

Domestication History
It has been thought that this tree has origin in the highlands of Ecuador & Peru but with recent molecular data, there may be suggestion that there is a meso-American origin. However, now it is grown in subtropical countries with Spain being its largest producer (Morton, 1987). It is also thought to have spread to Chile and Brazil in ancient times as it is currently naturalized in those countries highlands.

Cultivation Practices
The fruits are very sensitive to climate. If exposed to cold weather before fully mature then they may ripen incorrectly. If they’re exposed to heavy rains or excessive sun then the fruit may crack open. If the humidity is too high, then they have short storage lives (National Research Committee on Technology Innovation, 1989). It is typically grown in Spain, Guatemala, Bolivia, Peru, and other subtropical regions. 
To ensure reliable results of bearing fruit, trees are normally grafted or budded on seedling rootstock and done in the spring before the leaves drop  (Robert, 2014). The trees themselves prefer higher elevations to 5000 feet but can bear fruits at lower elevations as low as 800 feet (Love, 2012). Pollination is one of the most difficult tasks in cultivating a cherimoya tree. Since the flowers prevent self-pollination with the dichogamous flowering nature and the configuration of the petals, natural pollination is not reliable or conducive. Therefore, hand-pollination is essential in ensuring everything gets pollinated. The pollen would be collected in the evening, stored in a cool, dry place and then reapplied to the mature stigmas in the morning (Robert, 2014).

Nutritional Value and Part of the Plant Consumed
The fruit of the tree or the cherimoya is the part that is consumed. The enticing quality of the fruit is its custardy, creamy texture of the flesh, that give it the title of the custard apple (Arakelyan, 2021).The aromatic flavor is said to be a mix of banana, papaya, and pineapple. It is common to eat the ripe fruit straight out of the tree, cut open, and scooped with a spoon. It also has high nutritional value of around 1.5g of fiber, 21.7g of Calcium, 30.2 mg of Phosphorus, 0.117mg of Thiamine, 0.112g of Riboflavin, and 16.8mg of Ascorbic Acid (Morton, 1987).The cherimoya has micronutrients such as Magnesium, Calcium, and Phosphorus that are in two to four-fold higher in value than other common fruits such as apples.Cherimoya also serves as a great source of Ascorbic Acid (Gentile, 2021).

Position of Medicinal Research
The seeds should not be eaten since they can contain harmful side effects. The crushed seeds have been used as insecticide. There are also accounts of blindness resulting from the juice of the crushed seeds coming in contact with the eyes. This may be due to the chemical alkaloids found in the seeds such as reticuline, anonaine, lanuginosine, and liriodenine. Human ingestion of the seed can also cause intense photophobia, dilated pupils, vomiting, nausea, dryness in the mouth, flatulence, and other symptoms resembling the effects of a prescription medicine Atropine, used to treat the symptoms of low heart rate or as an antidote for overdose of mushroom poisoning.  In Mexican culture, the seeds are sometimes pulverized, mixed with grease, and applied on skin for parasitic skin disorders or lice. The skin of the fruit is also used to make a decoction for relieving pneumonia (Morton, 1987). The fruit itself is being studied as possibilities to remedy and offset medical conditions. Cherimoya is high in antioxidants which combat the oxidative stress on the body, lowering risks of cancer and heart disease. Cherimoya’s carotenoid antioxidants such as lutein may also boost eye health as lutein is the main antioxidant in the eyes that is essential in maintaining healthy eyes (Arakelyan 2021).. Also, since cherimoya has high macronutrient content of Potassium and Magnesium, consumption may prevent high blood pressure as those nutrients promote dilation of blood vessels to decrease blood pressure.
 

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