Musa (genus)

The genus Musa was first named by Carl Linnaeus in 1753.[5] The name is a Latinization of the Arabic name for the fruit, mauz (موز). Mauz meaning Musa is discussed in the 11th-century Arabic encyclopedia The Canon of Medicine, which was translated to Latin in medieval times and well known in Europe.[Note 1] Muz is also the Turkish, Persian, and Somali name for the fruit. Some sources assert that Musa is named for Antonius Musa, physician to the Emperor Augustus.[6] The word "banana" came to English from Spanish and Portuguese, which in turn apparently obtained it from a West African language (possibly Wolof).[7]

From the time of Linnaeus until the 1940s, different types of edible bananas and plantains were given Linnaean binomial names, such as Musa cavendishii, as if they were species. In fact, edible bananas have an extremely complicated origin involving hybridization, mutation, and finally selection by humans. Most edible bananas are seedless (parthenocarpic), hence sterile, so they are propagated vegetatively. The giving of species names to what are actually very complex, largely asexual, hybrids (mostly of two species of wild bananas, Musa acuminata and Musa balbisiana) led to endless confusion in banana botany. In the 1940s and 1950s, it became clear to botanists that the cultivated bananas and plantains could not usefully be assigned Linnean binomials, but were better given cultivar names.

Food served on a banana leaf, a traditional way of serving food more popular in southern India

Musa sectional systematics possesses a history dating back to 1887. In that year, M.P. Sagot published “Sur Le Genre Bananier”, where the genus Musa was first formally classified.[8] In this article, Sagot grouped the Musa species into three groups, although no section names were assigned to them. The grouping was based on morphological traits, establishing the trio as:

1. Bananas with fleshy fruit;
2. Ornamental bananas with upright inflorescences and bracts that were vibrantly colored; and
3. Bananas that were giant in size.

In 1893, five years after Sagot's article, J.G. Baker made the first formal designation of Musa sections. To do so, he named three subgenera which almost paralleled the sections that had been described by Sagot.[9] These sections were:

1. M. subg. Physocaulis Baker: a group defined by a bract with many flowers, inedible fruits, and a bottle-shaped stem.
2. M. subg. Rhodochlamys Baker: brightly-colored bracts with few flowers, usually inedible fruits, and cylindrical stems.
3. M. subg. Eumusa Baker which possessed green, brown, or dull-violet bracts with many flowers, usually edible fruits, and cylindrical stems.

After this classification, 50 years passed without revision to the banana sections. In 1947, Cheeseman reclassified the taxon based on morphological features and chromosome number.[10] This project proposed 4 sections:

1. M. sect. Eumusa Cheesman (2n = 2x = 22)
2. M. sect. Rhodochlamys (Baker) Cheesman (2n = 2x = 22)
3. M. sect. Australimusa Cheesman (2n = 2x = 20)
4. M. sect. Callimusa Cheesman (2n = 2x = 20)

The addition of another Musa section came in 1976 in G.C.G. Ardent's "The wild bananas of Papua New Guinea". The added section, M. sect. Ingentimusa Ardent, was based on a single species, Musa ingens.[11] This designation put the number of sections in Musa at five: Eumusa, Rhodochlamys, Callimusa, Australimusa, and Ingentimusa .

In the 21st century, genomics have become cheaper, more efficient, and more accurate, and Musa genetic research has increased exponentially. Research was conducted around a diversity of genomic markers (cpDNA, nrDNA, rDNA, introns, various spacers, etc.). The results of many of these studies suggested that the five sections of Musa defined by morphology (and listed above) were not monophyletic.[12][13]

Based on the incorrect section grouping, Markku Häkkinen proposed another reclassification of the Musa sections in 2013. Using a multitude of genetic evidence and markers from other studies, Häkkinen suggested the reduction of five Musa sections into two: Musa and Callimusa.[13] Unlike sectional classifications of the past, this hypothesis was based on genetic markers rather than morphological features or chromosome number. The two groups were generally formed by the clustering of the previously defined groups:

• Musa sect. Rhotochlamys and M. sect. Eumusa  became M. sect. Musa
• M. sect. Ingetimusa, M. sect. Callimusa and M. sect. Australimusa  became M. sect. Callimusa

The advance of genomic analysis technologies and further data on the relatedness of Musa species, formulated Häkkinen's two sections and later corroborated them as correct subcategories for the genus.[14][15][16] The history of Musa sections provides an example of genomics superseding morphological evidence and thus classifications.

The World Checklist of Selected Plant Families accepts 68 species and two primary hybrids, as of January 2013, which are listed below.[17] The assignment to sections is based on GRIN (where this gives the species),[18] regrouped according to Wong et al.[19]

Fruit stalk of Musa sp.

Banana flowers

[A] and [C] indicate known placement in the former sections Australimusa and Callimusa, respectively.[20]

• M. × alinsanaya R.V.Valmayor [A]
• M. azizii Häkkinen
• M. barioensis Häkkinen
• M. bauensis Häkkinen & Meekiong [C]
• M. beccarii N.W.Simmonds [A][Note 2]
• M. boman Argent [A]
• M. borneensis Becc. [C]
• M. bukensis Argent [A]
• M. campestris Becc. [C]
• M. coccinea Andrews [C] – scarlet banana
• M. exotica R.V.Valmayor [C]
• M. fitzalanii F.Muell. [A] – extinct
• M. gracilis Holttum [C]
• M. hirta Becc. [A]
• M. insularimontana Hayata [A]
• M. jackeyi W.Hill [A]
• M. johnsii Argent [A]
• M. lawitiensis Nasution & Supard. [C]
• M. lokok Geri & Ng
• M. lolodensis Cheesman [A]
• M. maclayi F.Muell. ex Mikl.-Maclay [A]
• M. monticola M.Hotta ex Argent [A]
• M. muluensis M.Hotta [A]
• M. paracoccinea A.Z.Liu & D.Z.Li [C]
• M. peekelii Lauterb. [A]
• M. salaccensis Zoll. ex Backer [A]
• M. textilis Née [A] – Abacá
• M. × troglodytarum L. [A] – the cultivated Fe'i bananas
• M. tuberculata M.Hotta [A]
• M. violascens Ridl. [C]
• M. viridis R.V.Valmayor et al.
• M. voonii Häkkinen

• M. ingens N.W.Simmonds

Musa acuminata with inflorescence

Japanese fiber banana (Musa basjoo) flowering at Cotswold Wildlife Park

Musa ornata 'Roxburgh' in China

Pink banana (Musa velutina) flower

• M. acuminata Colla – wild seeded banana, one of the two main ancestors of modern edible banana cultivars
  • M. acuminata subsp. zebrina [= M. sumatrana] – blood banana
• M. aurantiaca G.Mann ex Baker
• M. balbisiana Colla – wild seeded banana, one of the two main ancestors of modern edible banana cultivars
• M. banksii F.Muell.
• M. basjoo Siebold & Zucc. ex Iinuma – Japanese fiber banana, hardy banana[Note 3]
• M. cheesmanii N.W.Simmonds
• M. chunii Häkkinen
• M. griersonii Noltie
• M. itinerans Cheesman
• M. laterita Cheesman
• M. mannii H.Wendl. ex Baker
• M. nagensium Prain
• M. ochracea K.Sheph.
• M. ornata Roxb.
• Musa × paradisiaca L. = M. acuminata × M. balbisiana – many of the cultivated edible bananas
• M. rosea Baker
• M. rubinea Häkkinen & C.H.Teo
• M. rubra Wall. ex Kurz
• M. sanguinea Hook.f.
• M. schizocarpa N.W.Simmonds
• M. siamensis Häkkinen & Rich.H.Wallace
• M. sikkimensis Kurz
• M. thomsonii (King ex Baker) A.M.Cowan & Cowan
• M. velutina H.Wendl. & Drude – pink banana
• M. yunnanensis Häkkinen & H.Wang – Yunnan banana, wild forest banana
• M. zaifui Häkkinen & H.Wang

Varigated form of Musa sp.

Musa sp.

• M. arfakiana Argent
• M. celebica Warb. ex K.Schum.
• M. juwiniana Meekiong
• M. kattuvazhana K.C.Jacob
• M. lanceolata Warb. ex K.Schum.
• M. lutea R.V.Valmayor et al.
• M. sakaiana Meekiong et al.
• M. shankarii Subba Rao & Kumari
• M. splendida A.Chev.
• M. tonkinensis R.V.Valmayor et al.
• M. yamiensis C.L.Yeh & J.H.Chen

• Ensete davyae (Stapf) Cheesman (as M. davyae Stapf)
• Ensete gilletii (De Wild.) Cheesman (as M. gilletii De Wild. or M. martretiana A.Chev.)
• Ensete glaucum (Roxb.) Cheesman (as M. glauca Roxb.)
• Ensete lasiocarpum (Franch.) Cheesman (as M. lasiocarpa Franch.) – also placed in a separate genus as Musella lasiocarpa (Franch.) C.Y.Wu ex H.W.Li[21]
• Ensete livingstoniana (J. Kirk) Cheesman (as M. livingstoniana J.Kirk)
• Ensete perrieri (Stapf) Cheesman (as M. perrieri Claverie)
• Ensete superbum (Roxb.) Cheesman (as M. superba Roxb.)
• Ensete ventricosum (Welw.) Cheesman (as M. arnoldiana De Wild., M. ensete J.F.Gmel. or M. ventricosum (Welw.) Cheesman)
• Heliconia bihai (L.) L. (as M. bihai L.)

Plants of the Musa spp. including roots, flowers and fruits have been used in the folk medicine cultures of Africa, Asia, India and the Americas. Modern studies examining the properties of the fruits have found diversity of bioactive compounds among genotypes compared with commercially grown cultivars.[22]

When the Linnaean binomial system was abandoned for cultivated bananas, an alternate genome-based system for the nomenclature of edible bananas in section Musa was devised. Thus, the plant previously known by the "species" name Musa cavendishii became Musa (AAA Group) 'Dwarf Cavendish'. The "new" name shows clearly that 'Dwarf Cavendish' is a triploid, with three sets of chromosomes, all derived from Musa acuminata, which is designated by the letter "A". When Musa balbisiana is involved, the letter "B" is used to denote its genome. Thus, the cultivar 'Rajapuri' may be called Musa (AAB Group) 'Rajapuri'. 'Rajapuri' is also a triploid, expected to have two sets of chromosomes from Musa acuminata and one from Musa balbisiana. In the genome of edible bananas from section Musa, combinations such as AA, BB, ABB, BBB and even AAAB can be found.

For a more detailed explanation of this system and a list of some edible banana and plantain cultivars using it, see the List of banana cultivars.

No such nomenclature system has been developed for the group of edible bananas derived from section Callimusa. This group is known generally as the "Fe'i" or "Fehi" bananas, and numerous cultivars are found in the South Pacific region. They are very distinctive plants with upright fruit bunches, featuring in three of Paul Gauguin's paintings. The flesh can be cooked before eating and is bright orange, with a high level of beta carotene. Fe'i bananas are no longer very important for food, as imported foods have grown in popularity, although some have ritual significance. Investigations are under way to use the Fe'i karat bananas (the name derives from "carrot" due to the intense orange-yellow color of the fruit) in prevention of childhood blindness in Pohnpei.[23] Fe'i bananas probably derive mainly from Musa maclayi, although their origins are not as well understood as the section Musa bananas. Cultivars can be formally named, as e.g. Musa (Fe'i Group) 'Utafun'.