case against trans-pacific dispersal of the coconut by ocean currents

7
Case Against Trans-Pacific Dispersal of the Coconut by Ocean Currents 1 JOHN V. DENNIS 2 AND CHARLES R. GUNN z The question of the origin of the coconut whether or not it reached the Pacific coast of Central America through natural means or by human agency--has been debated for over one hundred years. On the basis of our studies of strand plants in gen- eral and their dispersal by ocean currents, we feel that a number of points regarding the capacity of the coconut for sea dispersal have been misunderstood. We also find that there are misconceptions concerning the role of ocean currents in disseminating various plant species. We have concluded that the coconut is an endemic of the Indo-Malaysian region. It spread by sea currents (Fig. 1) to many Pacific Island groups preceded a far-ranging distribution by primitive man. History It is of interest that two students of plant dispersal by ocean currents, Guppy (10) and Ridley (21), considered the New World to be the ancestral home of the coconut. Guppy, Ridley, and the still earlier Martius (18) attributed the presence of the coconut in Polynesia and westward to trans-Pacific dispersal via the South Equatorial Current. The argument for a New World origin cen- tered around the undisputed presence of the coconut on Cocos Island off Costa Rica and parts of the Pacific coast at the time of Columbus, and to the fact that virtually all of the palms in the tribe Cocoineae (except Elaeis guineensis Jacq.) had their origin in the New World. Another coeoid palm, Jubaeopsis caf#a Beceari, has been found in South Africa. Beceari (1) believes that this palm is more closely related to the coconut than to other eoeoid palms. This would tend to negate the theory that all eoeoid palms are endemic to the New World. 1 Submitted for publication February 7, 1971. 2 Free lance biologist, Leesburg, Virginia. a Collaborator, Department of Botany, Smith- sonian Institution, Washington, D. C. Cook (5) was one of the strongest pro- ponents of the New World origin concept. He was persuaded by vague references of early Spanish explorers to give the coconut a much wider New World range than any- one else who had studied its distribution. He proposed that the original home of the coconut was in areas of salt deposits in the interior of Colombia. Furthermore, he claimed that ocean currents have played no role whatsoever in the world distribution of the coconut. He argued that the coconut was incapable of establishing itself naturally on a seacoast and that man has been respon- sible for its spread. As to the coconut's thick outer husk, Cook believed that this is an adaptation to protect the embryo from injury when the fruit falls from the tree, rather than an adaptation for transport by ocean currents. Although many of Cook's arguments have been soundly refuted by Beecari and others, his views have recently been given serious consideration by Heyerdahl. Citing his own experience on the Kon Tiki and legends handed down from early Polynesian voy- agers, Heyerdahl (12, 13) seems to find many of Cook's views helpful in explaining presumed introduetions of the coconut from America to Polynesia by early travellers. Cook was one of the first to suggest that the coconut was brought to Cocos Island by early man and that it did not occur there naturally. Whatever the anthropological evidence may be for transport of the coconut west- ward by early man, and whether or not this has any bearing at all o11 the place of origin of the coconut, the fact remains that the coconut originated somewhere in the Indo- Malaysian region. De Candolle (8) and Beccari (1) were among earlier writers who strongly supported the Old World origin concept. De Candollc had at first favored the west coast of America as the home of the coconut. But on the basis of the antiq- 407

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Page 1: Case against trans-pacific dispersal of the coconut by ocean currents

Case Against Trans-Pacific Dispersal of the Coconut by Ocean Currents 1

JOHN V. DENNIS 2 AND CHARLES R. GUNN z

The question of the origin of the coconut whether or not it reached the Pacific

coast of Central America through natural means or by human agency--has been debated for over one hundred years. On the basis of our studies of strand plants in gen- eral and their dispersal by ocean currents, we feel that a number of points regarding the capacity of the coconut for sea dispersal have been misunderstood. We also find that there are misconceptions concerning the role of ocean currents in disseminating various plant species. We have concluded that the coconut is an endemic of the Indo-Malaysian region. It spread by sea currents (Fig. 1) to many Pacific Island groups preceded a far-ranging distribution by primitive man.

History It is of interest that two students of plant

dispersal by ocean currents, Guppy (10) and Ridley (21), considered the New World to be the ancestral home of the coconut. Guppy, Ridley, and the still earlier Martius (18) attributed the presence of the coconut in Polynesia and westward to trans-Pacific dispersal via the South Equatorial Current. The argument for a New World origin cen- tered around the undisputed presence of the coconut on Cocos Island off Costa Rica and parts of the Pacific coast at the time of Columbus, and to the fact that virtually all of the palms in the tribe Cocoineae (except Elaeis guineensis Jacq.) had their origin in the New World. Another coeoid palm, Jubaeopsis caf#a Beceari, has been found in South Africa. Beceari (1) believes that this palm is more closely related to the coconut than to other eoeoid palms. This would tend to negate the theory that all eoeoid palms are endemic to the New World.

1 Submitted for publication February 7, 1971. 2 Free lance biologist, Leesburg, Virginia. a Collaborator, Department of Botany, Smith-

sonian Institution, Washington, D. C.

Cook (5) was one of the strongest pro- ponents of the New World origin concept. He was persuaded by vague references of early Spanish explorers to give the coconut a much wider New World range than any- one else who had studied its distribution. He proposed that the original home of the coconut was in areas of salt deposits in the interior of Colombia. Furthermore, he claimed that ocean currents have played no role whatsoever in the world distribution of the coconut. He argued that the coconut was incapable of establishing itself naturally on a seacoast and that man has been respon- sible for its spread. As to the coconut's thick outer husk, Cook believed that this is an adaptation to protect the embryo from injury when the fruit falls from the tree, rather than an adaptation for transport by ocean currents.

Although many of Cook's arguments have been soundly refuted by Beecari and others, his views have recently been given serious consideration by Heyerdahl. Citing his own experience on the Kon Tiki and legends handed down from early Polynesian voy- agers, Heyerdahl (12, 13) seems to find many of Cook's views helpful in explaining presumed introduetions of the coconut from America to Polynesia by early travellers. Cook was one of the first to suggest that the coconut was brought to Cocos Island by early man and that it did not occur there naturally.

Whatever the anthropological evidence may be for transport of the coconut west- ward by early man, and whether or not this has any bearing at all o11 the place of origin of the coconut, the fact remains that the coconut originated somewhere in the Indo- Malaysian region. De Candolle (8) and Beccari (1) were among earlier writers who strongly supported the Old World origin concept. De Candollc had at first favored the west coast of America as the home of the coconut. But on the basis of the antiq-

407

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408 E C O N O M I C BOTANY

FIc. 1. Sea currents of the world with straight arrows representing warm currents and wavy arrows representing cold currents, [Reproduction of plate facing page 46 (10). Used by permis- sion of John Bartholomew and Co. and Benn Bros. Ltd.]

uity of the coconut in Asia, the many names given it by the various peoples who knew it there, its early economic importance in Asia, the many Old World varieties of the coconut, and other evidence, he became persuaded that the coconut originated in island archipelagos off the coast of Asia. Transport to the New World, he postulated, was either by ocean currents or peoples from Asia bringing the coconut with them in bold voyages eastward across the Pacific. Beecari suggested that the coconut evolved either upon existing islands in the eastern Indian Ocean or upon "some other lands or islands, existing in former times between Africa and India."

Evidence giving credence to the Old World theory as summarized by Menon & Pandalai (19) is, in part, open to question. Their "new forms of cocoid palm" refers probably to the introduced Elaeis (23), because no other cocoid palms are suggested as native in Madagascar. Their evidence is accepted concerning the existence of coco- nuts in East Africa at the time of Vasco da Gama and the record of cultivation of coco-

nuts at about 300 B.C. in Ceylon and India in post-vedic time. However, their state- ment about Cocos fossils found in Plioeene deposits in North Auckland, New Zealand, is questioned by Couper (7), who con- sidered the fossils to be of Miocene age.

Bruman (2), assuming an Old World origin, suggested that the coconut reached the Pacific coast by way of the Equatorial Gounter Current. He estimated that a drift of about seven months would take coconuts from Pahnyra, the nearest coconut-bearing atoll, to the vicinity, of Cocos Island. He found it difficult to believe that Polynesian voyagers could cover such long distances. A far different view, however, is taken by HeyerdahI, who plaeed much more con- fidenee in the ability of sea-faring peoples whose voyages took them through the Pa- cific and who are thought to have carried such staple foods as the sweet potato, plantain, yam bean, and the coconut (13).

Chiovenda (4) takes the view that the coconut evolved through natural selection on coral islands in the western Indian Ocean and, in time, became dispersed by ocean

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DENNIS AND G U N N : DISPERSAL OF THE COCONUT 409

@ A

SEED COAT ENDOSPERh

EXOCARP MESOCARP ENDOCARP

Fro. 2. Coconut fruit. A: Apex of endocarp show the three depressions or pores, and the renmant of the tricarpellate condition of the im- mature ovary. B: Complete fruit cut open to reveal internal structures. Buoyancy is due in part to the fibrous mesocarp and to the hollow center of the seed.

currents to various island groups of the region. He attributed its presence in the Pacific to introductions by prehistoric man. This view is upheld by Saner (22), who attributed the presence of the coconut on numerous uninhabited islands in the Indian Ocean at the time of their discovery, to sea dispersal. He fnrther stated that Chio- venda's views regarding the place of origin of the coconut and its subsequent dispersal seem to be the best hypothesis available. He added that "it is not yet possible to dearly sort out natural and artificial dis- persal in the eastern spread of the species." Comer (6) is also inclined toward an insular Pacific origin for the coconut.

Drift Capacity Among the many strand and estuary

plants of the world that owe their distribu- tion in part or wholly to ocean currents, the coconut appears to have a somewhat greater capacity than most for long-distance travel.

Its buoyancy appears to be due chiefly to its light fribrous mesocarp, and perhaps, in a lesser degree, to the cavity within the seed which is surrounded by a watertight bony endocarp (Fig. 2). Sauer pointed out that varieties of the coconut with thick husks are particularly well adapted to oceanic dispersal. He stated that coconuts from the Seychelle Islands, the Nicobars, Madagas- car, and from Palmyra in the Pacific have exceptionally thick husks. Flotation experi- ments with coconuts in Hawaii indicate that individual nuts may float for at least 110 days (9).

The oecurrences of coconuts washing ashore on European beaches probably does not offer evidence one way or another of the coconut's seaworthiness. Guppy ( I i ) stated that one occasionally finds coconuts on the South Devon coast of England and that coconuts have been picked up on Nor- wegian beaches since the middle of the 18th Century. Cook (5) cited a report of a coconut reaching Ronsay in the Orkneys. We believe that coconuts on European beaches are "garbage" from nearby shipping lanes and have not been carried from Florida or the West Indies by the Gulf Stream.

Coconuts reaching tlodriques Island in the Indian Ocean would have had a voyage of around 3,000 miles (22). Most evidence, it would seem, indicates that the coconut will stay afloat from three to four months. This is long enough under conditions pre- vailing in a number of ocean current systems to permit an ocean voyage of around 3,000 miles.

Abil i ty to Establ ish I tself

For years the coconut was cited as the classic example of a plant that owed its distribution largely to ocean currents. Cook, however, took the position that the coconut is unable to establish itself on a seashore without assistance from man. The truth lies somewhere in between.

Hill (15) noted five localities where coconuts apparently seeded themselves nat- urally: cays in British Honduras, rocky islets in the Fiji group, the east coast of Trinidad, Cocos-Keeling Atoll in the Indian Ocean (a frequently referred to example of probable natural reproduction), and the well-known example of Krakatau and adja-

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410 ECONOMIC BOTANY

cent islets where coconuts appeared some- time after the eruption of 1883. New islets appeared briefly after an eruption in the Krakatau ,area in 1928-30. Only 18 months after its appearance, 41 germinating coco- nuts were found on one islet.

The ability of the coconut successfully to establish itself depends upon environmental conditions. An ample fresh water supply, good drainage, and opportunity for un- restricted root development are prime re- quirements. The sun damages exposed seedlings; yet, coconut seedlings cannot survive in dense shade. Along beaches, sea breezes tend to ameliorate the damaging effect of intense sunlight. Under most situa- tions, seedlings require watering and other attention from man. In addition, there are natural enemies, including pigs, crabs, bandi- coots, and rats.

As an I n s u l a r Species

The popular view that every tropical island is a natural haven for coconuts and other palms is erroneous. Only two palms, Nypa fruticans Wurmb. and Cocos nucifera L., are dispersed to any appreciable degree by ocean currents, and palms generally are absent from the natural floras of islands (21). Man, to be sure, has altered the picture through his introductions. According to Child (3), the present-day distribution of the coconut extends over most of the islands and coasts of the tropics, and even in some places goes outside the txopie zone. The coconut is essentially a cultivated plant, and it behaves like one in its poor ability for self-propagation.

Before man's introductions, the coconut would appear to have been an insular species of limited distribution. Not only can the coconut be traced to an insular environment on the basis of historical evidence, but in its sea dispersal it shows itself to be better adapted to insular than mainland situations. This is seen in the lack of reports of the coconut establishing itself naturally upon the shores of a continent or even upon islands of the size of Borneo or Madagascar.

The coconut owes its presence on the coast of tropieal West Africa to introduetinns by the Portuguese (3). Its presence on the coast of East Africa at the time of Vaseo da Gama seems to have been limited to the

island of San Jorge, near Beira in present- day Mozambique. It is not known whether this was an introduction by Arab voyagers or the result of natural dispersal by sea. In commenting upon the fact that he never found a viable coconut in the strand drift of South Africa, Muir (20) states that the coconut is a cultivated plant in East Africa.

Early cultivation of the coconut in Asia makes it impossible to determine if there were any endemic colonies on that continent. It seems highly improbable that the coconut either had its origin on a continental main- land or ever established itself naturally on one. Comer (6) ruled this out in the case Asia and large islands to the east on the basis of the presence of mammals destructive to fruits and young foliage--e.g., monkeys, bears, squirrels, rats.

Australia, a more recently settled con- tinent, provides evidence of the inability of the coconut to establish itself on the main- land. In spite of coconuts growing on islands off the northeast coast, none were present on the mainland when the first European colonists arrived (5). Australia, with a much different fauna than Malaysia, might have been expected to provide a more congenial environment. In assessing this problem, Bruman (2) concluded that the robber crab (Birgvs latro) prevented estab- lishment of the coconut on the coast of Australia. While this crab is extremely destructive to the plumule of the young coconut, it should be pointed out that robber crabs and coconuts have existed side by side on numerous Indian Ocean and Pacific islands since, at least, the early days of European voyages of discovery.

Recent investigation (3) have shown the robber crab to be much less destructive of mature coconuts than it was formerly thought to be. In our opinion, the inability of the coconut to establish itself on the Australian mainland would appear t o be more of a question of environmental unsuit- ability than the result of depredation by any particular animal species.

There is little indication that sea-drifted coconuts fare any better on either coast of tropical America than they would on any other continental coast. There are, to be sure, questions still to be resolved concern- ing the origin of the coconut and whether

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DENNIS AND G U N N : DISPEI:tSAL OF THE COCONUT 411

or not it was brought to the Pacific coast by early sea-faring peoples. As the evidence seems increasingly to favor introductions by man, there is ever less reason to believe that the pre-Columbian coconut groves variously stated to have existed from Colombia to Colima, Mexico, were a result of natural sea dispersal. In fact, Heyerdahl & Ferdon (14) flatly state that "it is now established that this palm was carried by aboriginal man one way or the other across the major ocean gap separating tropic America with Cocos Island from the Marquesas group."

An interesting sidelight on the probable ability of the coconut to establish itself on American coastlines is seen in a statement by Sauer (22) : "I have seen more volunteer coconuts sprouting in beach drift on a single islet of Cocos-Keeling atoll than along hundreds of miles of Caribbean and Mexican Gulf coasts . . . . " The coconut would appear to have all the qualifications of a plant especially adapted to coral islands. It has shown itself to be poorly suited for establish- ing itself on coastlines of continents.

Some strand plants of insular origin prob- ably do not have the capacity for self- establishment upon coasts of mainlands. This might be particularly true of species that evolved upon coral atolls. The biotic conditions that permit propagation and growth on the shores of an atoll might not be widely duplicated on shores of larger islands or upon coastlines of continents. Generally, strand plants seem well adapted to a variety of shoreline habitats. Some, to be sure, are limited to rocky shorelines, others to the mud and congested growth of mangrove swamps, and still others to sandy shorelines.

Bar r ie r Effec t of the Eastern Paci f ic

Although several current systems appear prominently on Figure 1 in the vicinity of the equator extending from one end of the Pacific to the other, it does not follow that these systems are connecting links between the littoral floras of the New World and Polynesia. As Johnston (17) noted: "There are copious sources of drift fruit and seeds available in both the east and the w e s t . . . Yet only in the distribution of tlhizophora samoensis (Hochr.) Salvosa does there seem to be any evidence that these currents may

have been useful in plant dispersal in the eastern parts of the P a c i f i c . . . For some reason the waters of the eastern Pacific have not been a highway, but rather a barrier, for ocean-disseminated species."

Commenting upon the same subject, Rid- ley observed "there is very little of the American flora in Polynesia. The only sea- transported plants in both areas are Dioclea violacea Benth., Mucuna urens Medikus, and Rhizophora mangle L.'" On hypothetical grounds Ridley suggests that a number of other plants of American origin may have migrated from east to west via Pacific cur- rents, among them Sophora, Guettarda spe- ciosa L., "though that species is not yet known from America," Ipomoea alba L., Inocarpus edulis Forst., and as mentioned earlier, Cocos nucifera L. Depending upon whose authority one wishes to cite, the Equatorial Current has taken from one to no more than 10 New World species to Polynesia.

Evidence of any reverse movement is. virtually non-existent. Bruman suggested the coconut reached the New World via the Equatorial Counter Current. Ridley listed only Stictocardia tiliaefolia Hallier f., which he suggested probably "reached America from Polynesia by sea-currents." The unproductiveness of the Counter Cur- rent can easily be explained if we accept Heyerdahl's (13) word that "this so-called Counter Current is nothing but an inter- rupted series of upwellings and is of scant use to trans-Pacific voyagers."

The lack of westward disseminule migra- tion in swiftly moving Equatorial Currents is difficult to explain. However, these systems may bear more plant material than the record of successful introductions indi- cates. Many drift seeds and fruits lose their germinative capacity after prolonged exposure to sea-water. However, various species Of Mucuna, Entada, Dioclea, Caesal- pinia, Canavalia, and Ipomoea are extremely seaworthy and could be expected to reach islands in Polynesia with their germinative capacities unimpaired. These genera con- tain species which are pantropic or nearly so in distribution, and hence there would be no way to recognize possible new material arriving via the Equatorial Currents.

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412 E C O N O M I C BOTANY

Discussion

Assigning a place of origin to the coconut and an explanation for its occurrence on two sides of the world prior to the voyages of Columbus have often seemed insoluble problems. Part of the difficulty is that theorists have tended to expect too little or too much of ocean currents as agents of dispersal. We have noted the fact that 3,000 miles seems to be the maximum dis- tance that a coconut will remain afloat with its viability unimpaired. This is approxi- mately half the distance a coconut would have to drift from a seacoast to land in either an easterly or westerly direction in the equatorial eastern Pacific.

The existence of a current system does not necessarily mean a ready source of trans- port for fruits and seeds of strand plants. While a number of current systems have played a highly important role in the dis- persal of strand plants, others have not. Evidence is lacking, for example, of any plant species being brought eastward from Polynesia to the coast of America by ~he Equatorial Counter Current.

Sea-dispersed species have usually evolved in tropical regions where there are many islands. One of the richest regions for speeiation is Malaysia. Currents from this region have taken numerous species east- ward into Polynesia and many others west- ward to islands of the Indian Ocean, often as far as the coast of East Africa. Few sea- dispersed species have evolved along con- tinental coastlines. This is especially true along coasts of the New World. Many of the tropical disseminules that are carried northward by the Gulf Stream are river or estuary species with little capacity for long- term viability. Others are from plants that are typical of the littoral floras of the West Indies, and some of these have a pantropic distribution.

The fact that the coconut occurred only on the west coast of America at the time of Columbus would put it in a region where few plants have evolved the capacity for sea dispersal. Moreover, such sea-dispersed plants that occur on the west coast of America, for the most part, occur on the east coast. For example, of 39 sea-dispersed species whose fruits or seeds were found in the strand drift of San Jose Island in the

Gulf of Panama, all but 10 were common to both sides of the Isthmus of Panama (17). The fact that strand floras of both sides are so similar suggests a common evolution at a time when the waters of the Pacific and Atlantic were joined, or a time antedating the Pleiocene.

The mystery of how the coconut reached western America, if it was brought by man, remains to be unravelled. But it seems far more reasonable to believe that primitive man, and not ocean cun'ents, was involved. For the coconut to have had a recent origin on the west coast of America, and for it to have spread from there to the Old World tropics without having crossed the narrow Isthmus of Panama, is not in keeping with what is known of its history or the history of strand plants in general. We agree with de Candolle, Beceari, and others who would look for the origin of the coconut somewhere among the islands of the Indo-Malaysian region. And we see no objection to its having been dispersed by sea to many island groups before man spread it around the world.

Most of the arguments used by Cook in support of a New World origin were poorly received in his own day (1) and are even less plausible in light of present knowledge. It is therefore strange to find someone at this late date championing some of the positions taken by Cook and at the same time looking for ways to bolster the badly sagging New World origin concept. We are led to conclude that Heyerdahl finds it more convenient for his theories concerning the migrations and voyages of ancient peoples to have the place of origin of the coconut in the New rather than the Old World. We agree with Heyerdahl only in maintaining that man, not ocean currents, was the agent instrumental in the conveyance of the coco- nut across the vast expanses of the eastern Pacific.

L i t e ra tu re Ci ted

i. Beccari, O. 1917. The origin and disper- sal of Cocos nucifera. Philippine Journal Science (Botany) 12C: 27-43.

2. Brnman, H.J . 1944. Some observations on the early history of the coconut in the New World. Acta Americana 2 (3): 220-243.

3. Child, R. 1964. Coconuts. Longmans, Green and Co. Ltd., London, 215 p.

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DENNIS AND G U N N : D I S P E l l S A L OF THE COCONUT 413

4. Chiovenda, E. 1921-23. La crulla del cocco. Webbia 5: 199-294, 359--449.

5. Cook, O. F. 1910. History of the coco- nut palm in America. Contributions U. S. National Herbarium 14(2): 1-280.

6. Corner, E. J. H. 1966. The natural his- tory of palms. University of California Press, Berkeley, 393 p.

7. Couper, R.A. 1952. The spore and pol- len flora of the Cocos-bearing beds, Mangonui, North Auckland. Transac- tions Royal Society, New Zealand 79: 340-348.

8. de Candolle, A. 1967. Origin of culti- vated plants. Reprint of 2nd Edition (1886), Hafner Publishing Company, New York, 468 p.

9. Edmonson, C.H. 19,41. Viability of coco- nut seeds after floating in sea. Occasional Papers Bernice P. Bishop Museum 16 ( 12 ) : 293-304.

10. Guppy, H. B. 1906. Observations of a naturalist in the Pacific between 1896 and 1899. 2: Plant Dispersal. Macmil- lan, London and New York, 627 p.

11. Guppy, H. B. 1917. Plants, seeds, and currents in the West Indies and Azores. Williams and Norgate, London, 531 p.

12. Heyerdahl, T. 1952. American Indians in the Pacific, The theory behind the Kon-Tiki Expedition. George Allen & Unwin, Ltd., London.

13. Heyerdahl, T. 1968. Sea routes to Poly- nesia. Rand McNally & Co., Chicago, 323 p.

14. Heyerdahl, T. & E. N. Ferdon, Jr. 1961. Archaeology of Easter Island. 1: Mono-

graphs of the School of American Re- search and the Museum of New Mexico, 124: 133-134, 151-153.

15. Hill, A.W. 1929. The original home and mode of dispersal of the coconut. Nature 124: 133-34, 151-53.

16. Hill, A. W. & W. Docters van Leeuwen. 1933. Gernainating coconuts on a new volcanic island, Krakatoa. Nature 132: 674.

17. Johnston, I .M. 1949. The botany of San Jos6 Island (Gulf of Panama). Sargentia 8: 1-306.

18. Martius, C. F. P. yon. 1823-50. Historia naturalis palmarum. 2: Brasiliae palmas singulatim descriptione et icone illustrat.

19. Menon, K. P. V. & K. M. Pandalai. 1958. The coconut palm: A monograph. In- dian Central Coconut Committee, Erna- kulam, India, 384 p.

20. Muir, J. 1937. The seed-drift of South Africa and some influences of ocean cur- rents on the strand vegetation. Botanical Survey Memoir No. 16: Dept. Agricul- ture Forestry, Pretoria, 108 p.

21. Ridley, H . N . 1930. The dispersal of plants throughout the world. L. Reeve, Ashford, Kent, 744 p.

22. Sauer, J . D . 1967 . Plants and man on the Seychelles coast. A study in his- torical biogeography. University of Wis- consin Press, Madison, 132 p.

23. Zeven, A . C . 1967. The semi-wild oil palm and its industry in Africa. Agricul- tural Research Reports 689 (Wagenin- gen), p. 26-27.

A d d e n d u m

A paper by J. W. Purseglove [The Origin and Distribution of the Coconut, Tropical Science 10(4): 190--199. 1968] came to our attention after our article was in press. We can find no fault with this writer's conclusion that the present-day coconut originated in Melanesia. We believe, however, that his view of a pro- genitor of the coconut probably arising among the Coeoid palms of northwestern South Amer- ica and reaching Polynesia either by ocean

currents or via Antarctica in geological times needs qualification. An ocean current dispersal of a progenitor is entirely in keeping with the facts we have presented about currents and the pantropic distribution of certain sea-side plants. On the other hand, a land distribution through Antarctica in geological times is not in accord with the isolated floras and faunas that existed in New Zealand and Australia at the time of their discoveries.