STUDIES IN MUSACEAE IH. Fossil Records of Musaceae and the Origin of Bananas

BY R. K. JAIN [Botany Section, College of Agriculture, Punjab Agricultural University, Hi:sar (Punjab), India] Received October 13, 1964

(Communicated by Dr. V. Puff, r.A.se.)

INTRODUCTION

IN recent years much work has been done on the taxonomy, phytogeography and cytogenetics of bananas. As a result of these studies Cheesman (1947 a) has revived Ensete Horan. as a genus separated from Musa L. This division was opposed by Chakravorti (1951), who suggested that Ensete should be reduced to the status of a sub-genus of Musa L. He has also concluded that Musa (including Ensete and all the cultivated forms of bananas) originated in Assam-Burma-Siam and Indo-China.

The following pages are devoted to a review of the literature concerning the fossil records of Musaceae and a study of the bearing of the fossils on the problem of the origin and interrelationship of bananas.

FOSSIL RECORDS OF MUSACEAE Many plant fossils have been referred to Musaceae but the affinities of some of them are so doubtful that it is difficult to be sure that they are even Angiosperms. For example, Scitaminites musaeformis Sternburg (1825), a fragment of a fossil leaf, and Musaeites primaevus Presl. (in Sternburg, loc. cit.), a stem, are from the Upper Carboniferous of Bohemia (Czechoslovakia). Considering the age of these fossils it becomes doubtful whether they were Angiosperms or not, as there is hardly any known Pre- Cretaceous fossil which can be safely considered as an Angiosperm (Scott, Barghoorn and Leopold, 1960). Definite Musaceous fossils are known from the Tertiary or Post-Tertiary strata of Java, Europe and America and Late-Cretaceous or Early Eocene formations of Colombia and India (Fig. 1).

* In a paper of Berry (1925 a) one comes across the spellings Musaphyllum, This appears to be a misprint and the correct spellin~ are Musophyllum. 170 Studies in Musaceae--III 171

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I 0 0 0 "o B6 172 R.K. JAIN These records are mostly in the form of fossil leaf fragments which have mostly been described under the name Musophyllum* Goeppert. The latter is a form-genus propounded by Goeppert (1854) for banana-like leaves from the Tertiary of Java with M. truncatum Goeppert as the type species. Sub- sequently, such banana-like leaves have been discovered from various places in America and Europe, e.g., from the Eocene of Yellowstone Park, Wyoming, Colorado, and from somewhat younger formations in Cuba, Trinidad, Colombia, Venezuela, Hesse (Germany), Croatia (Yugoslavia), France, and Italy (Berry, 1921a, b; 1925b; 1930; 1935; 1939). These fossils are too fragmentary to permit generic identification. Impressed by the fact that there are 30-40 living species of Heliconia cxc!usively confined to America, and by the absence of any wild species of Musa (including Ensete) in that region, Berry (1921 b) thought that "the genus Musa was never present in the Western hemisphere despite th~ fact that it flourished greatly under cultivation in the American Tropics at the present time". Thus he saw " no reason for not substituting Heliconia for Musophyllum in the Tertiary records of Tropical America ". Accordingly he substituted Heliconia elegans (Engelhardt) Berry for Musophyllum elegans Engelhardt (Berry, 1921 b).

In 1925 Berry described some carbonized fossil seeds which were dis- covered in the coal beds of Cerros de Guadalupe and Montserrat which peak the Eastern border of Bogota. He named them Musa enseteformis Berry (1925 a). As regards the age of these seeds, Berry was doubtful but he thought that they might belong to the Oligocene. The name "Musa enseteformis" was chosen by Berry (1925 a) because of the close resemblance between the fossil seeds and those of "Musa ensete" (now Ensete ventricosum Cheesman, 1947 a; Baker and Simmonds, 1953 a, b). There is no reason to doubt the identification of these fossil seeds, but since "Musa ensete" and its allied species have now been put in a separate genus, Ensete, the fossil leeds also belong to this genus. Accordingly, I have trans- ferred this fossil species to Ensete (Jain, 1960). Further, according to the International Code of Botanical Nomenclature, the specific epithet ensete- forints after the generic epithet Ensete does not amount to repetition of generic epithet. So, the correct name of this species should be Ensete enseteformis (Berry) comb. nov. As such I withdraw my earlier proposal when I named this species as Ensete berryi (Jain, 1960). Berry's discovery was important in several respects. Firstly, because these seeds w~re found in the Continent where Musa is no longer represent~t Studies in MusaceaewllI 173 by any living species. Secondly, this was the first unequivocal record of any genus of Musaceae. Finally, it led botanists to reconsider the question of the nativity of bananas; whether they arose in the Old World where we lind all the living wild species of the genus today, or in the New World whence the fossil seeds have been discovered. This led Berry (1925 a) to revise his idea about changing the American Musophyllum spp. to Heliconia spp. Thus he wrote, " In the light of the fossil seeds from Colombia, it is possible that some or all these American Musophyllum may represent the genus Musa, a point which can never be determined by foliage alone ". In spite of these remarks he assigned fossil fragments of leaves from Brazil to Heliconia as tt. bahiana Berry, and from Cuba as Heliconia sp. (Berry, 1935, 1939), and the species which was renamed as H. elegans (Elgelhardt) Berry continued to be placed in Heliconia. As pointed out above, there is no morphological basis for identifying these fossils with Heliconia and now even the phyto- geographical one has become unsound with the discovery of the fossils of Ensete from Colombia. Therefore, it will be misleading to retain these fossils as Heliconia spp. especially when it appears quite probable that some of them may represent bananas particularly Ensete. Hence, it is desirable to transfer the so-called Heliconia spp. to the non-committal form-genus, Musophyllum. Apart from these fossil fragments of leaves there is a report of a fossil fruit of banana from the Munzenberger sandstones (of Miocene age) in Germany (K1/ihn, 1928). Kirchheimer (1957) indicates that this is not a fossil of Musaceae. Also Huertas, Gustavo, and van der Hammen (1953) have discovered a cast looking very much like a fruit of banana from the Cretaceous of Colombia. However, since no cellular or structural details are preserved, it is difficult to make any further comments. Recently, Mahabale (MS) has described a petrified Musaceous petiole from Mohgaonkalan beds of the Deccan lntertrappean Series, India (of Upper Cretaceous or Lower Eocene age). It has not been referred to any living genus. More recently, the present author has described a petrified fruit from the same locality of the Deccan Intertrappean Series, India, as Musa cardiosperma Jain (1963 a), which has been referred to the section Musa (Eumusa of Cheesman, 1947 b), and a petrified pseudostem of Musaceae Musocaulon indicum Jain (1963 b), which could not be referred to any living genus of Musaceae. The fruit was about 10-12 cm. long and about 1.3 cm. in diameter containing a little pulp and about 30-40 seeds arranged in three locules, the seeds being nearly of the same size as we find in modern species of bananas. B7 174 R.K. JAIN

INTERRELATIONSHIP OF Musa L. AND Ense'e HORAN

Earlier, the genus Musa L. was subdivided into three subgenera, Physo- caulis, Eumusa, and Rhodochlamys (Baker, 1893). This treatment of the genus was subsequently accepted by the taxonomists without question. It was in 1947 that Cheesman (1947 a) in a revision of genus raised the sub- genus Physocaulis to the rank of a genus Ensete .Horan. Concerning their relationship, Cheesman (1947 a) observed that it would be unsafe to regard Musa as "derived from" Ensete and almost impossible to imagine the reverse; yet the two genera (as indicated by their long accepted association in one) are sufficiently close to postulate a common ancestral stock "at no very remote geological time" (italics mine). He believed this " common stock" to have been characterised by large size; stoloniferous habit, non-encircling leaf-shea.ths, gradual leaf-bract transition, persistent bracts, hermaphrodite flowers, and fruits with few large seeds. From such a common stock two lines of descent are suggested to have diverged. One line survived in Ensete, and the other in Musa (sensu restrictiore). Ensete, he supposed, became monocarpic but otherwise retained most of the primitive characters, and by contrast Musa developed fruits with more numerous and smaller seeds." A few years later, Chakravorti (1951) questioned the desirability of raising Physocaulis to the rank of a genus (Ensete). At the same time he suggested that Eumusa (one of the sections of Musa, sensu restrictiore) has directly descended from the species of Ensete. More recently, Simmonds (1962) has supported and elaborated Cheesmanrs hypothesis. The fossil records also support Cheesman's hypothesis to a great extent. The similarity of the fossil seeds (Ensete enseteformis) to those ofE. vetricosum (Welwitch.) Cheesman appears to show that species of Ensete have retained essentially the same shape and size of the seeds. Musa cardiosperma, which is the solitary definite record of Musa, agrees with the primitive Musa line of descent in having relatively few seeds. It is, however, evident from the size of the seeds of the fossil species (Jain, 1963 a) that quite early in the evolution of this genus the size of the seeds had been reduced almost to the size of the seeds of the present-day species of Musa. The fossil records are inadequate to indicate whether Musa has directly descended from Ensete or both arose from a common ancestral stock. The two genera (Musa and Ensete) are distinctly recognizable as such. since at least the Early Eocene. Therefore, the fossil records are entirely against Studies in Musaceae--III 175

Chakravorti's suggestion that Ensete be reduced to the status of a subgenus of Musa. At the same time Cheesman's estimate of the dating was not correct when he wrote that the two genera had a common ancestral stock " ...... at no very remote geological time". If at all, such a stock must have existed some time in the Mezozoic Era.

ORIGIN OF Musa L.

Musa L. comprises about 37 known species with a possibility that "about another six good species await discovery" (Simmonds, 1962). The genus is broadly an opportunistic one, and the species differ in their ecological demand and toIerances. Mostly the species of this genus thrive naturally in the tropical rain forests of S.-E. Asia. Bananas are, however, extensively cultivated in Africa and Amer;ca. With the exception of Musa acuminata, which has a wide distribution there are no wild species of Musa in Africa. It is believed to have been introduced there either from North India via Arabia through the horn of Africa or from Malaysia by way of Madagascar about the time of Christ. The presence of banana in America has led to much speculation about its antiquity in that continent. After studying the historical date De Candolle (1886) reached the conclusion that Musa was not indigenous to America. But Cook (1903, in Berry, 1925 a) advocated the theory that Musa is a native of America. With the discovery of fossil seeds of banana, Berry (1925 a) was inclined to believe that Musa is a native to the New World. The recent discovery of a possible banana from Colombia (Huertas, Gustavo and van der Hammen, 1953) has again led palaeobotanists to reconsider the issue of the nativity of Musa in America (Andrews, 1961). But it has already been pointed out above that the fossil seeds described by Berry (1925 a) have been referred to Ensete (Jain, 1960), and the so-called banana from Colombia may not be a banana at all. Therefore, there are no palaeobotanical reasons to believe that Musa is a native to America. On the other hand, there is a historical record that banana was introduced into America by Portuguese Fri~tr Toms~ide Burlanga from the West Africa to the Canary Islands and thence to Hispaniola in 1516 (Oviedo, 1556, in De CandoUe, 1886). This record has been usually relied upon (Reynolds, 1951 ; Simmonds, 1962). The Assam-Burma-Thailand region in S.-E. Asia has been considered as the area of main centre of diversity and hence centre of origin of ancestral stock of bananas (Chakravorti~ 1951; Simmonds, 1962), From this the 176 R.K. JAIN

Musa stock spread widely in the eastward direction. This conclusion has been arrived at after a combined consideration of phytogeography, taxonomy, and cycogenetics of bananas. Apparently, however, the pattern of distri- bution of these plants has played an important role in pin-pointing the native home of Musa. Therefore, it will be unreasonable to disregard the past distribution of the genus in determining its nativity.

The distribution of Musophyllum species (Fig. 1) suggests that during the past geological eras, the bananas and/or their allies were also distributed in areas where they are not present now. Also, there is enough evidence to show that during the late Cretaceous or Eocene, whichever is the age of the Deccan Traps (see Sahni, 1940) the Penninsular India enjoyed a troigical humid climate. Similar climate now prevails in the area marked as the centre of diversity and origin of bananas. Therefore, the occurrence of fossil banana in Central India indicates that the latter must also have been a part of the native home of bananas.

ORIGIN OF Ensete

Cheesman (1947 a) considered Ensete primarily an African genus. This consideration was obviously based on the supposed occurrence of about n neteen species of this genus !n continental Africa. But Chakravorti (1951) was of the view that Ensete also arose in S.-E. Asia and most likely in the area Assam-Burma-Thailand-Indo-China. In support of his hypothesis, Chakra- vorti (1951) noted that "to this area if S. China is added we find that out of sev,en S.-E. Asian species, as many as five occur here. I do not know an area of similar size in Africa that contains as many species" In recent years the taxonomic revision of Ensete (Baker and Simmonds, 1953 a) has given a better understanding of the pattern of distributions of this genus. Now Ensete is known to contain only 6-7 valid species which are equally divided between Africa and Asia (Simmonds, 1962). After considering the evidences of taxonomy, geography and cytogenetics ofEnsete, Simmonds (1962) has also reached the conclusion that Assam-Burma- Thailand area is the "main centre of diversity" and thus the main centre of origin of Musa as well as Ensete. Apparently, therefore, the evidence of species concentration in a region has outweighed the other evidences, relating to the problem of nativity of this genus. But the presence of Ensete in Tertiary fossil records of America and the distribution of Musophfllum species have almost been ignored, Studies in Musaceae--III 177

Simmonds (1962) has noted that "' Ensete is an old declining group that has no evident centre" It appears more so to the palaeobotanists who are aware of the presence of Ensete in the Tertiary of America and the distributi0n of Musophyllum species, some of which may represent Ensete. Chakrav0rti (1951) is, however, of the view that Ensete originated in S.-E. Asia and it reached America via the Pacific Ocean. But considering the geographical and ecological factors, it appears highly improbable. The Pacific Ocean must have offered as effective a geographical barrier in the past as it does today for the migration of plants like Ensete which require a continuous land surface for their migration. On the other hand, the occurrence of Musophyllum species in parts of Europe and Northern America indicates that Ensete could have reached America more easily via the Northern hemisphere. Further, it has been shown above that it is possible that some of the Muso- phyllum species may represent bananas, particularly Ensete. In that ease it obviously follows that problem of nativity of Ensete is only exposed rather than solved.

SUMMARY

A review of the literature on the fossil records of Musaceae shows that many fossil fragments of leaves have been referred to this family as Muso- phyllum spp. and some as Heliconia spp. It has been shown that there is little justification for naming the American banana-like fossil leaves as Heliconia spp.

As regards Musa and Ensete, their only definite fossil records are Musa cardiosperma Jain and Ensete enseteformis (Berry) Jain respectively. In the light of the fossil records, the maintenance of Ensete as a genus distinct from Musa L. has been supported. Further, a study of the past and present- day distributing Musa L. has shown that the Central India must have been a part of the native home of this genus. In the light of fossil evidence the problem of nativity of Ensete has also been discussed.

ACKNOWLEDGEMENTS

The author is grateful to Dr. R. N. Lakhanpal under whose inst~iring guidance the present work was done at the Birbal Sahni Institute of Palaeo- botany, Lucknow. I am also greatly thankful to Prof. V. Puri for kindly reading the manuscript. 178 R.K. JAIN

REFERENCES

Andrews, H. N., Jr. Studies in Palaeobotany, New York and London, 1961. Baker, J. G. "A synopsis of the genera and species of Musaceae,'" Ann. Bot., 1893, 7, 189-222. Baker, R. E. D. and Simmonds, "The genus Ensete in Africa," Kew Bull., 1953 a, pp. 405-16. N. W. .. "A correction," Ibid., 1953 b, p. 574. Berry, E. W. .. "Tertiary fossil plants from Costa Rica," Proc. U.S. Nat. Mus., 1921 a, 59, 169-85. .. "Tertiary fossil plants from Venezuela," Ibid., 1921 b, 59, 553-79. .. "A banana in the Tertiary of Colombia," Amer. J. Sci., 1925 a, 10, 530-37. .. "The Tertiary flora of the island of Trinidad," B.W.I. Johns Hopkins Univ. Studies Geol., 1925 b, 6, 71-160. .. "A flora of Green River Age in Wind River Basin of Wyoming," U.S. Geol. Survey, Prof. Paper, 1930, 165 B, 68. .. "Tertiary plants from Brazil," Proc. Amer. Phil. Soc., 1935, 75, 565-90. .. "A Miocene flora from the gorge of the Yumari River, Matansas, Cuba," Johns Hopkins Univ. Studies Geol., 1939, 13, 95-135. Chakravorti, A. IC .. "OHgin of cultivated bananas of South-East Asia," J. Genetics Plant Breeding, Special Symposium, New Delhi, 1951, 11, 34--46. Cheesman, E. E. .. "The classification of bananas. L The genus Ensete Horan.," Kew Bull., 1947a, pp. 97-106. .. "The classification of bananas. IL The genus Musa L.,'" Ibid., 1947 b, pp. 106-17. De Candolle, A. .. Origin of Cultivated'Plants, New York, 1886, Reprint 1959. Goeppert .. Die Tertiary Flora auf der lnsel Java, Elberfeld, 1854. *Huertas, Gustavo, and van der "Un posible banano (Musa) fossil del Cretaceo de Colombia," Hammcn, T. Revista Acad. Colombian Ciencas Exactas, Fisicas Nay., 1953, 9, 115-17. Jain, R. K. •. "" Ensete Berryi: Revised name for Musa enseteformis Berry," Nature, 1960, 187, 342-43. .. "Studies in Musaceae. 1. Musa cardiosperma sp. nov., a fossil banana fruit from the Deccan Intertrappean Series, India," The Palaeobotanist, 1963 a, 12, 45-58. •. "Studies in Musaceae. 2. Musocaulon indicum gen. et sp. nov., petrified pseudostem from the Deccan Intertrappean Series, India," Ibid., 1963 b, 12, 115-20. Kirchhe'nner, F, ,. Die Laubgewachse der BrowzholdetTzeit, Halle, 1957, 38, Studies in Musaceae--lll 179

Klahn "Ueber den eroten Fund einer fossUicn Bananenfruet und ihre Fossilifation," Notizhl. Hess. Geol. Landesanst, 1928, 5, 100-16. Mahabalc, T.S. .. "A fossil musaceaus petiole," (MS.). *Reynolds, Ph. K. .. "Earliest evidence of banana culture," Y. Amer. Orient. Soc., 1951, p. 71. Sahni, B. .. "The Deccan Traps: An episode of the Tertiary Era," Proc. 27th Indian Sci. Congr. Madras, 1940, pp. 3-19. Scott, R. A., Barghoorn, E. S. "How old are the Angiosperms?" Amer. J. Sci., 1960, and Leopold, E. B. pp. 284-99. Simmonds, N.W. .. The Evolution of the Bananas, Frome and London, 1962. *Sternburg, G.K. .. Versuch einer Geognostischen Botanischen Darsklling der Flora der Vorweit., Tell 4, Leipsig and Prague, 1925. * Not seen in the original.