Coconut Trees

The coconut tree (''Cocos nucifera'') is a member of the palm tree family ( Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the fruit, which botanically is a drupe, not a nut. The name comes from the old Portuguese word '' coco'', meaning "head" or "skull", after the three indentations on the coconut shell that resemble facial features. They are ubiquitous in coastal tropical regions and are a cultural icon of the tropics.

The coconut tree provides food, fuel, cosmetics, folk medicine and building materials, among many other uses. The inner flesh of the mature seed, as well as the coconut milk extracted from it, form a regular part of the diets of many people in the tropics and subtropics. Coconuts are distinct from other fruits because their endosperm contains a large quantity of clear liquid, called ''coconut water'' or ''coconut juice''. Mature, ripe coconuts can be used as edible seeds, or processed for oil and plant milk from the flesh, charcoal from the hard shell, and coir from the fibrous husk. Dried coconut flesh is called copra, and the oil and milk derived from it are commonly used in cookingfrying in particularas well as in soaps and cosmetics. Sweet coconut sap can be made into drinks or fermented into palm wine or coconut vinegar. The hard shells, fibrous husks and long pinnate leaves can be used as material to make a variety of products for furnishing and decoration.

The coconut has cultural and religious significance in certain societies, particularly in the Western Pacific Ocean, Western Pacific Austronesian cultures where it features in their mythologies, songs, and oral traditions. It also had ceremonial importance in pre-colonial animistic religions. It has also acquired religious significance in South Asian cultures, where it is used in Hindu rituals. It forms the basis of wedding and worship rituals in Hinduism. It also plays a central role in the Coconut Religion of Vietnam. The falling of their mature fruit has led to preoccupation with death by coconut.

Coconuts were first domesticated by the Austronesian peoples in Island Southeast Asia and were spread during the Neolithic via their seaborne migrations as far east as the Pacific Islands, and as far west as Madagascar and the Comoros. They played a critical role in the long sea voyages of Austronesians by providing a portable source of food and water, as well as providing building materials for Austronesian outrigger boats. Coconuts were also later spread in historic times along the coasts of the Indian and Atlantic Oceans by South Asian, Arab, and European sailors. Based on these separate introductions, coconut populations can still be divided into Pacific coconuts and Indo-Atlantic coconuts, respectively. Coconuts were introduced by Europeans to the Americas only during the colonial era in the Columbian exchange, but there is evidence of a possible pre-Columbian introduction of Pacific coconuts to Panama by Austronesian sailors. The evolutionary origin of the coconut is under dispute, with theories stating that it may have evolved in Asia, South America, or on Pacific islands. Trees grow up to tall and can yield up to 75 fruits per year, though fewer than 30 is more typical. Plants are intolerant of cold weather and prefer copious precipitation, as well as full sunlight. Many insect pests and diseases affect the species and are a nuisance for commercial production. About 75% of the world's supply of coconuts is produced by Indonesia, the Philippines, and India. The coconut tree is the official state tree of Kerala, India.

Description

''Cocos nucifera'' is a large palm, growing up to tall, with pinnate leaves long, and pinnae long; old leaves break away cleanly, leaving the trunk smooth. On fertile soil, a tall coconut palm tree can yield up to 75 fruits per year, but more often yields less than 30. Grimwood, p. 18. Given proper care and growing conditions, coconut palms produce their first fruit in six to ten years, taking 15 to 20 years to reach peak production.

True-to-type dwarf varieties of Pacific coconuts have been cultivated by the Austronesian peoples since ancient times. These varieties were selected for slower growth, sweeter coconut water, and often brightly-colored fruits. Many modern different varieties are also grown, including the Maypan coconut, King coconut, and Macapuno. These vary by the taste of the coconut water and color of the fruit, as well as other genetic factors.

Fruit

Botanically, the coconut fruit is a drupe, not a true nut. Like other fruits, it has three layers: the exocarp, mesocarp, and endocarp. The exocarp is the glossy outer skin, usually yellow-green to yellow-brown in color. The mesocarp is composed of a fiber, called coir, which has many traditional and commercial uses. Both the exocarp and the mesocarp make up the "husk" of the coconut, while the endocarp makes up the hard coconut "shell". The endocarp is around thick and has three distinctive germination pores (micropyles) on the distal end. Two of the pores are plugged (the "eyes"), while one is functional.

The interior of the endocarp is hollow and is lined with a thin brown seed coat around thick. The endocarp is initially filled with a multinucleate liquid endosperm (the coconut water). As development continues, cellular layers of endosperm deposit along the walls of the endocarp up to thick, starting at the distal end. They eventually form the edible solid endosperm (the "coconut meat" or "coconut flesh") which hardens over time. The small cylindrical embryo is embedded in the solid endosperm directly below the functional pore of the endosperm. During germination, the embryo pushes out of the functional pore and forms a haustorium (the coconut sprout) inside the central cavity. The haustorium absorbs the solid endosperm to nourish the seedling.

Coconut fruits have two distinctive forms depending on domestication. Wild coconuts feature an elongated triangular fruit with a thicker husk and a smaller amount of endosperm. These allow the fruits to be more buoyant and makes it easier for them to lodge into sandy shorelines, making their shape ideal for ocean dispersal.
Domesticated Pacific coconuts, on the other hand, are rounded in shape with a thinner husk and a larger amount of endosperm. Domesticated coconuts also have more amounts of coconut water.
These two forms are referred to by the Samoan terms ''niu kafa'' for the elongated wild coconuts, and ''niu vai'' for the rounded domesticated Pacific coconuts.

A full-sized coconut fruit weighs about . Coconuts sold domestically in coconut-producing countries are typically not de-husked. Especially immature coconuts (6 to 8 months from flowering) sold for coconut water and softer jelly-like coconut meat (known as "green coconuts", "young coconuts", or "water coconuts"), where the original coloration of the fruit is more aesthetically pleasing.

Whole mature coconuts (11 to 13 months from flowering) sold for export, however, typically have the husk removed to reduce weight and volume for transport. This results in the naked coconut "shell" with three pores more familiar in countries where coconuts are not grown locally. De-husked coconuts typically weigh around . coconuts are also easier for consumers to open, but have a shorter postharvest storage life of around two to three weeks at temperatures of or up to 2 months at . In comparison, mature coconuts with the husk intact can be stored for three to five months at normal room temperature .

Roots

Unlike some other plants, the palm tree has neither a taproot nor root hairs, but has a fibrous root system.Thampan, P.K. (1981). ''Handbook on Coconut Palm''. Oxford & IBH Publishing Co. The root system consists of an abundance of thin roots that grow outward from the plant near the surface. Only a few of the roots penetrate deep into the soil for stability. This type of root system is known as fibrous or adventitious, and is a characteristic of grass species. Other types of large trees produce a single downward-growing tap root with a number of feeder roots growing from it. 2,000–4,000 adventitious roots may grow, each about large. Decayed roots are replaced regularly as the tree grows new ones.

Inflorescence

The palm produces both the female and male flowers on the same inflorescence; thus, the palm is monoecious. However, there is some evidence that it may be polygamomonoecious and may occasionally have bisexual flowers. The female flower is much larger than the male flower. Flowering occurs continuously. Coconut palms are believed to be largely cross- pollinated, although most dwarf varieties are self-pollinating.

Taxonomy

Phylogeny

The evolutionary history and fossil distribution of ''Cocos nucifera'' and other members of the tribe Cocoseae is more ambiguous than modern-day dispersal and distribution, with its ultimate origin and pre-human dispersal still unclear. There are currently two major viewpoints on the origins of the genus ''Cocos'', one in the Indo-Pacific, and another in South America. The vast majority of ''Cocos''-like fossils have been recovered generally from only two regions in the world: New Zealand and west-central India. However, like most palm fossils, ''Cocos''-like fossils are still putative, as they are usually difficult to identify.
The earliest ''Cocos''-like fossil to be found was ''"Cocos" zeylanica'', a fossil species described from small fruits, around × in size, recovered from the Miocene (~23 to 5.3 million years ago) of New Zealand in 1926. Since then, numerous other fossils of similar fruits were recovered throughout New Zealand from the Eocene, Oligocene, and possibly the Holocene. But research on them is still ongoing to determine which of them (if any) actually belong to the genus ''Cocos''. Endt & Hayward (1997) have noted their resemblance to members of the South American genus '' Parajubaea'', rather than ''Cocos'', and propose a South American origin. Conran ''et al.'' (2015), however, suggests that their diversity in New Zealand indicate that they evolved endemically, rather than being introduced to the islands by long-distance dispersal. In west-central India, numerous fossils of ''Cocos''-like fruits, leaves, and stems have been recovered from the Deccan Traps. They include morphotaxa like ''Palmoxylon sundaran'', ''Palmoxylon insignae'', and ''Palmocarpon cocoides''. ''Cocos''-like fossils of fruits include ''"Cocos" intertrappeansis'', ''"Cocos" pantii'', and ''"Cocos" sahnii''. They also include fossil fruits that have been tentatively identified as modern ''Cocos nucifera''. These includes two specimens named ''"Cocos" palaeonucifera'' and ''"Cocos" binoriensis'', both were dated by their authors to the Maastrichtian–Danian of the early Tertiary (70 to 62 million years ago). ''C. binoriensis'' has been claimed by their authors to be the earliest known fossil of ''Cocos nucifera''.

Outside of New Zealand and India, only two other regions have reported ''Cocos''-like fossils, namely Australia and Colombia. In Australia, a ''Cocos''-like fossil fruit, measuring , were recovered from the Chinchilla Sand Formation dated to the latest Pliocene. Rigby (1995) assigned them to modern ''Cocos nucifera'' based on its size. In Colombia, a single ''Cocos''-like fruit was recovered from the middle to late Paleocene Cerrejón Formation. The fruit however was compacted in the fossilization process and it was not possible to determine if it had the diagnostic three pores that characterize members of the tribe Cocoseae. Nevertheless, the authors Gomez-Navarro ''et al.'' (2009), assigned it to ''Cocos'' based on the size and the ridged shape of the fruit.

Further complicating measures to determine the evolutionary history of ''Cocos'' is the genetic diversity present within ''C. nucifera'' as well as its relatedness to other palms. Phylogenetic evidence supports the closest relatives of ''Cocos'' being either '' Syagrus'' or '' Attalea'', both of which are found in South America. However, ''Cocos'' is not thought to be indigenous to South America, and the highest genetic diversity is present in Asian ''Cocos'', indicating that at least the modern species ''Cocos nucifera'' is native to there''.'' In addition, fossils of potential ''Cocos'' ancestors have been recovered from both Colombia and India. In order to resolve this enigma, a 2014 study proposed that the ancestors of ''Cocos'' had likely originated on the Caribbean coast of what is now Colombia, and during the Eocene the ancestral ''Cocos'' performed a long-distance dispersal across the Atlantic Ocean to North Africa. From here, island-hopping via coral atolls lining the Tethys Sea, potentially boosted by the ocean currents at the time, would have proved crucial to dispersal, eventually allowing ancestral coconuts to reach India. The study contended that an adaptation to coral atolls would explain the prehistoric and modern distributions of ''Cocos'', would have provided the necessary evolutionary pressures, and would account for morphological factors such as a thick husk to protect against ocean degradation and provide a moist medium in which to germinate on sparse atolls.

Etymology

The name ''coconut'' is derived from the 16th-century Portuguese word '' coco'', meaning 'head' or 'skull' after the three indentations on the coconut shell that resemble facial features. ''Coco'' and ''coconut'' apparently came from 1521 encounters by Portuguese and Spanish explorers with Pacific Islanders, with the coconut shell reminding them of a ghost or witch in Portuguese folklore called '' coco'' (also ''côca''). In the West it was originally called ''nux indica'', a name used by Marco Polo in 1280 while in Sumatra. He took the term from the Arabs, who called it جوز هندي ''jawz hindī'', translating to 'Indian nut'.Elzebroek, A.T.G. and Koop Wind (Eds.). (2008). ''Guide to Cultivated Plants''. CABI. pp
186–192
. ''Thenga'', its Tamil/Malayalam name, was used in the detailed description of coconut found in '' Itinerario'' by Ludovico di Varthema published in 1510 and also in the later '' Hortus Indicus Malabaricus''. Grimwood, p. 1.

Carl Linnaeus first wanted to name the coconut genus ''Coccus'' from latinizing the Portuguese word ''coco'', because he saw works of other botanists in middle of the 17th century use the name as well. He consulted the catalogue ''Herbarium Amboinense'' by Georg Eberhard Rumphius where Rumphius said that ''coccus'' was a homonym of ''coccum'' and ''coccus'' from Greek ''kokkos'' meaning "grain" or "berry", but Romans identified ''coccus'' with " kermes insects"; Rumphius preferred the word ''cocus'' as a replacement. However, the word ''cocus'' could also mean "cook" like ''coquus'' in Latin, so Linnaeus chose ''Cocos'' directly from the Portuguese word ''coco'' instead.

The specific name ''nucifera'' is derived from the Latin words ''nux'' (nut) and ''fera'' (bearing), for 'nut-bearing'.

History

Distribution and habitat

Coconuts have a nearly cosmopolitan distribution thanks to human action in using them for agriculture. However their historical distribution was likely more limited.

Origin

Modern genetic studies have identified the center of origin of coconuts as being the Central Indo-Pacific, the region between western Southeast Asia and Melanesia, where it shows greatest genetic diversity.Perera, Lalith, Suriya A.C.N. Perera, Champa K. Bandaranayake and Hugh C. Harries. (2009). "Chapter 12 – Coconut". In Johann Vollmann and Istvan Rajcan (Eds.). ''Oil Crops''. Springer. pp
370–372
. Their cultivation and spread was closely tied to the early migrations of the Austronesian peoples who carried coconuts as canoe plants to islands they settled. The similarities of the local names in the Austronesian region is also cited as evidence that the plant originated in the region. For example, the Polynesian and Melanesian term ''niu''; Tagalog and Chamorro term ''niyog''; and the Malay word ''nyiur'' or ''nyior''. Other evidence for a Central Indo-Pacific origin is the native range of the coconut crab