coco-de-mer

Coco de mer
Coco de mer with fruit
Conservation status
Vulnerable (IUCN)
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Liliopsida Order: Arecales Family: Arecaceae Genus: Lodoicea
Binomial name
Lodoicea maldivica (J.F.Gmelin) Persoon

The Vallée De Mai palm forest, where coco-de-mer are growing. Photograped at Praslin, Seychelles

The Coco de mer (Lodoicea maldivica), the sole member of the genus Lodoicea, is a palm endemic to the islands of Praslin and Curieuse in the Seychelles. It formerly also occurred on St Pierre, Chauve-Souris and Ile Ronde (Praslin) in the Seychelles group but has become extinct on these islands.

It grows to 25-34 m tall. The leaves are fan-shaped, 7-10 m long and 4.5 m wide with a 4 m petiole. It is dioecious, with separate male and female plants. The male flowers are catkin-like, up to 1 m long. The mature fruit is 40-50 cm in diameter and weighs 15-30 kg, and contains the largest seed in the plant kingdom. The fruit, which requires 6-7 years to mature and a further two years to germinate, is sometimes also referred to as the sea coconut, double coconut, coco fesse, or Seychelles nut.

Lodoicea maldivica, the scientific name of the Coco de mer, dates from centuries past when the seychelles were uninhabited. Back then the coconuts would be carried by the sea currents and drifted to the Maldives where they were an important trade item.

Mature fruit

Male coco de mer inflorescence. Photograped at Praslin, Seychelles

The Seychelles nut was once believed to be a sea-bean or drift seed, a seed designed to be dispersed by the sea. However, it is now known that the viable nut is too heavy to float, and only rotted out nuts can be found on the sea surface^{[citation needed]}, thus explaining why the trees are limited in range to just two islands. The sailors who first saw the nut floating in the sea imagined that it resembled a woman's disembodied buttocks. This fanciful association is reflected in one of the plant's archaic botanical names, Lodoicea callipyge Comm. ex J. St.-Hil., in which callipyge is from Greek words meaning 'beautiful rump'. Other botanical names used in the past include Lodoicea sechellarum Labill. and Lodoicea sonneratii (Giseke) Baill.

Until the true source of nut was discovered in 1768, it was believed by many to grow on a mythical tree at the bottom of the sea; European nobles in the sixteenth century would often have the shells of these nuts cleaned and decorated with valuable jewels as collectibles for their private galleries. The coco de mer is now a rare protected species.

The name of the genus, Lodoicea, is derived from Lodoicus, the Latinised form of Louis, in honour of King Louis XV of France.

The species is grown as an ornamental tree in many areas in the tropics, and subsidiary populations have been established on Mahé and Silhouette Islands in the Seychelles to help conserve the species.

Description

The coco de mer belongs to the Coryphoidae subfamily and tribe Borasseae. Borasseae is represented by four genera in Madagascar and one in Seychelles out of the seven worldwide. They are distributed on the coastlands surrounding the Indian ocean and the existing islands within. Borassus, the genus closest to Lodoicea, has about five species in the "old world," one species in Africa, one in India, South-East Asia and Malaysia, one in New Guinea and two species in Madagascar (Uhl and Dransfield, 1987).

The coco de mer is the most interesting species of the six monospecific endemic palms in Seychelles since it is the "only true case of island gigantism among Seychelles flowering plants, a unique feature of Seychelles vegetation" (Proctor, 1984). It is one of the most universally well-known plants and holds three botanical records; the largest fruit so far recorded weighed 42 kg; the mature seeds weighing up to 17.6 kg are the world's heaviest (Uhl and Dransfield, 1987; Wise, 1998; Carlstrom, unpublished) and the female flowers are the largest of any palm (Uhl and Dransfield, 1987; Wise, 1998).

Of the six endemic palms it is the only dioecious species, with male and female flowers located on different plants. A selective review of the biology of the species was recently published by Edwards, Kollmann & Fleischmann (2002).

Habit

The coco de mer palm is robust, solitary, up to 30 m tall with an erect, spineless, stem which is ringed with leaf scars (Calstrom, unpublished). The base of the trunk is of a bulbous form and this bulb fits into a natural bowl, or socket, about 2.5 ft in diametre and 18 inches in depth, narrowing towards the bottom. This bowl is pierced with hundreds of small oval holes about the size of a thimble with hollow tubes corresponding on the outside through which the roots penetrate the ground on all sides, never, however, becoming attached to the bowl; their partial elasticity, affording an almost imperceptible but very necessary "play" to the parent stem when struggling against the force of violent gales.

Leaves

The crown is a rather dense head of foliage with leaves that are stiff, palmate up to 10 m in diametre and petioles of two to four metres in length. The leaf is plicate at the base, cut one third or more into segments 4-10 cm broad with bifid end which are often drooping. A triangular cleft develops at the petiole base (Uhl and Dransfield, 1987).

Flowers

The clusters of staminate flowers are arranged spirally and are flanked by very tough leathery bracts. Each has a small bracteole, three sepals forming a cylindrical tube, and a three-lobed corolla. There are 17 to 22 stamens. The pistillate flowers are solitary and borne at the angles of the rachis and are partially sunken in it in the form of a cup. They are ovoid with three petals as well as three sepals (Uhl and Dransfield, 1987). It has been suggested that they may be pollinated by aninals such as the endemic lizards which inhabit the forest where they occur (Beaver and Chong Seng, 1992). Pollination by wind and drain are also thought to be important (Edwards, Kollman and Fleischmann, 2002). Only when Locoicea begins to produce flowers is it possible to determine the sex of the plant which can very from 11 to 45 years and more (Chong Seng, pers.comm. 2006; Andre, pers.comm. 2006).

Inflorescences

The inflorescences are interfoliar, lacking a covering spathe and shorter that the leaves. The staminate inflorescence is catkin-like, one to two metres long and generally terminal and solitay, sometimes two or three catkins may be present. The pistillate inflorescences are also one to two metres long unbranched and the flowers are borne on a zig-zagging rachilla (Wise, 1998).

Fruit

The fruit is bilobed, flattened, 40 to 50 cm long ovoid and pointed, and contains usually one but occasionally two to four seeds. The epicarp is smooth and the mesocarp is fibrous. The endosperm is thick, relatively hard, hollow and homogenous. The embryo sits in the sinus between the two lobes. During germination a tubular cotyledonary petiole develops that connects the young plant to the seed. The length of the tube is reported to reach about four metres (Uhl and Dransfield, 1987). Beaver and Chong Seng (1992) state that in the Vallee de Mai the tube may be up to 10 m long.

References

• Nature Protection Trust of Seychelles (1998). Lodoicea maldivica. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 05 May 2006. Listed as Vulnerable (VU A1cd v2.3)
• Arkive: Lodoicea maldivica
• Palm Society of Australia: Lodoicea maldivica description and photo gallery
• Hutchinson, 1959, The Families of Flowering Plants (2nd ed.)
• Fleischer-Dogley, F. (2006). Towards sustainable management of Lodoicea maldivica (Gmelin) Persoon, PhD thesis, University of Reading, UK.

See Also

Drift seed

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