How to Name a Banana

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Bananas are oddballs when it comes to their naming process. Species of wild banana follow the standard binomial process: Musa acuminataMusa cheesmaniiMusa velutina, etc. Their cultivars however have a nomenclature all their own. Developed by Norman Simmonds and Kenneth Shepherd in 1955, the system classifies cultivated bananas into genome groups and subgroups.

Genome Group

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see notes for M. balbisiana

A genome group is based on the contributions made by wild banana species. This contribution is written out as: AA, AB, AAA, AAB, ABB, Fe'i bananas. Apart from Fe'i bananas, each letter is an abbreviated form of the Musa species it descends from. Which means AA received eleven chromosomes from each M. acuminata parent. These parents were most likely subspecies of M. acuminata and not the original wild species. The same goes for the AB genome group, eleven chromosomes from a M. acuminata subspecies, and eleven from M. balbisiana.

To avoid confusion, we call cultivated diploids 'edible diploids', since their ancestors—M. acuminata and M. balbisiana—are diploids in their own right—AA and BB.

Our current bananas are the result of a great intermingling of variations on wild species and subspecies, which in turn hybridised with even more variations. From wild bananas, to edible diploids (AA, AB) which in turn gave rise to triploids (AAA, AAB, ABB) and a small number of tetraploids (AAAA, AAAB, AABB, ABBB). This intermingling was both the result of human intervention, as well as nature being its creative, morphing self. A higher number of ploidy (starting with the triploids) generally means that the hybridisation is human caused.

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Subgroup

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If you're wondering to which cultivars I'm referring to in my morphological descriptions, ask me in the comments.

see notes for full cultivar names

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Cultivated bananas come in all shapes and sizes, as do wild species. From the Hawaiian striped 'A'ea'a' cultivar to the 'Grand Nain' cultivar—which graces many fruit bowls—to the dark red skin of the Micronesian 'Karat Pwehu'. They come as small as a finger. With stubby, square, or pointed ends. With white flesh, as well a dark yellow, and orange—cultivars within the Iholena subgroup even have salmon-pink flesh. The skin of their fruit can range from yellow to orange, from dark red to deep maroon.

They can be short and plump, skinny and long, short and skinny. They can be high in starch and low in sugar, they can be unbelievably creamy, others overly sweet. Some can be eaten raw, some need to be cooked. And, the plants themselves can be the size of a person or they can tower several meters high, and any variation in between.

Related to each other through somatic mutation we sort these morphological expressions into subgroups. Each expressed through similar morphological traits.

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How to build a name

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From species down to groups to subgroups, and now you have all the pieces to build a banana name. First we mention the genus: Musa. Then, we mention its genome group and subgroup—if there is one—between round brackets (adding round brackets around the group and the subgroup or just the subgroup is a matter of preference). And, we close the name by mentioning its cultivar name in single quotation marks. Since, Fe'i bananas and a few other cultivars don't have any subgroups we drop the subgroup name from the formula. 

Musa genome group (subgroup) 'cultivar name' or Musa (genome group subgroup) 'cultivar name'

There is a beauty to a botanical name, in the way it designates and points you towards its heritage. On the other hand, there is something about the local names many cultivars are known under (see notes). They might stir up some or a great deal of confusion, but they tell you something about the relationship local populations have with their cultivated bananas

Musa AAA (Gros Michel) 'Gros Michel' | during the first part of the 20th century it was the most exported banana, but it was commercially wiped out during the 1950's due to Panama Disease (Fusarium Wilt - race 1). Once it became clear the cultivar was too vulnerable, the large fruit companies started to phase out the Gros Michel, replacing it with several cultivars within the Cavendish Group, which also belongs to the AAA genome group. The 'Gros Michel' is still grown in some smallholder's farms and backyard gardens.

Musa AAB (Iholena) 'Iholena Lele' | the subgroup was domesticated in the Pacific region, and together with Maoli-Popouli bananas are loosely known as Pacific plantains, because of their close relationship to African plantains. The fruit has yellow skin when unripe, as well as ripe, and salmon-pink flesh. Like other Iholenas, the fruit is arranged rather loose and grows perpendicular to its main axis. 

Musa (AA Pisang Mass) 'Sucrier' | the fruit of the 'Sucrier' cultivar is rather ickle, about the length of a finger. It's very sweet, hence its name, and one of the most widely grown AA cultivars. It's also one of the world's most popular local bananas (Ploetz et al, 2007). The cultivar is resistant to Fusarium Wilt.

Musa (Fe'i group) 'Karat Pwehu' | a short, chunky— not small—banana with dark red skin once ripe, and deep yellow to orange flesh. The sap of the plant is quite remarkable with its deep red to purple colour. The fruit is rich in beta-caratone—a precursor to Vit. A. Karat bananas grow in the Federated States of Micronesia. Fe'i bananas were domesticated as edible bananas independent from M. acuminata and the offspring between M. acuminata and M. balbisiana. Their ancestry is still being researched.

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Bananas might be oddballs, but they have a logical, and rather beautiful system. One that isn't always easy to understand from the first go, or the second, or even the third, and one that's especially hard if you're missing pieces. But, it is a system that works. That makes sense. That can be built on. And, one that grows with the discoveries being made. Which raises the question: Why don't more cultivars use this system?


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M. balbisiana | generally accepted knowledge tells us an edible BB doesn't exist, because M. balbisiana, unlike M. acuminata, never developed the ability to produce parthenocarpic fruit—the ability to produce fruit without fertilisation. But, a small number of scientists don't agree with this. At the moment, though we don't know with certainty that it doesn't exist or existed in the past. Promusa has an excellent explanation on a possible BBB cultivar named 'Saba'.

At the moment, the Kew (Royal Botanic Gardens) database: World Checklist of Selected Plant Families doesn't have any subspecies listed for M. balbisiana, only varieties (a taxonomic rank between subspecies and form, varieties occur naturally).

Triploids, tetraploids, ploidy | a triploid means one parent did not undergo normal meioses—copying one set of chromosomes—and donated both copies of its chromosomes. Ploidy is the number of sets of chromosomes in a cell, thus diploids have two sets, triploids have three, and tetraploids have four, and so on. Starting around four you can call ploidy polyploids.

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Cultivars | for an overview of bananas in the Pacific region and their other names, the following article is very helpful: Banana and plantain—an overview with emphasis on Pacific island cultivars. The article was published in 2007, so some information, like the four sections of banana, is already outdated. The four sections were made into two sections 'Musa' (11 chromosome pairs) and 'Callimusa' (10 chromosome pairs) in 2013. As a taxonomical rank it sits below genus and above species. Musa combines the previous Eumusa and Rhodochlamys, and Callimusa combines the old Callimusa section with the Australimusa section.

A'ea'a | Musa (AAB Maoli-Pōpō'ulu) 'Manini' | also known as ‘Koa‘e’, 'Hawaiian Variegated', and Manini. Variegation, within botany, means parts of a plant's morphology or the whole plant have different colour zones. Think of parts of the leaves coloured light green, while other parts are dark green.

Grand Nain | Musa (AAA Cavendish group) 'Grand Nain', one of the most popular cultivars worldwide.

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Thank you to Anne Vézina from Promusa for helping me with my research, and aiding me in better understanding the taxonomical and science side of bananas. As well as Gabriel Sachter-Smith for pointing out a few minor mistakes and for so generously donating his time to further explain the taxonomy and genetic complexity of bananas.

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This article is part of a larger project on bananas that I'm working on. If it feels like I've only touched on certain aspects of this wonderful berry, don't fret, I'm quite smitten with them. Over the coming months I'll publish cultivar profiles and articles on banana morphology, taxonomy, as well as the historical, social, and political aspect. If you'd like to contribute, either by offering your expertise in the field, as a grower, or aficionado, or if you'd just like to add your two cents, then meet me in the comments or send me an email.

Illustrations | banner image: banana leaves (generic), Musa (Fei bananas) 'Karat Pwehu' (ripe and unripe) | in text: Musa (AAA) Cavendish Group (non-specific cultivar).



Resources

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Bitten by botany, have a look at these

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This article was amended on 2016, May 24th.

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