Lodoicea

Lodoicea, commonly known as the sea coconut, coco de mer, or double coconut, is a monotypic genus in the palm family. The sole species, Lodoicea maldivica, is endemic to the islands of Praslin and Curieuse in the Seychelles, and was historically found on the neighboring small islets of St Pierre, Chauve-Souris, and Ile Ronde. while other sources say that Lodoicea is from Laodice, the daughter of Priam and Hecuba.

Lodoicea belongs to the subfamily Coryphoideae 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 coasts 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.

Description

right|thumb|The Vallée de Mai palm forest in Praslin

right|thumb|Lodoicea maldivica seed from the Royal Ontario Museum's green plant herbarium.

It generally grows to tall. The leaves are fan-shaped, 7–10 m long and 4.5 m wide with a 4 m petiole in mature plants. However, juveniles produce much longer petioles, up to long. It is dioecious, with separate male and female plants. The male flowers are arranged in a catkin-like inflorescence up to long 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, love nut, double coconut, coco fesse, or Seychelles nut.

While the functional characteristics of Lodoicea are similar to other trees of monodominant forests in the humid tropics, its unique features include a huge seed, effective funnelling mechanism and diverse community of closely associated animals. These attributes suggest a long evolutionary history under relatively stable conditions. Of the six monospecific endemic palms in Seychelles, Lodoicea is the "only true case of island gigantism among Seychelles flowering plants, a unique feature of Seychelles vegetation". It holds a number of botanical records:

It produces the heaviest fruit of any palm, weighing up to .
The fruit is composed of three carpels which are the largest of any flowering plant (although the carpels of Entada spp. are longer).
These fruit are the slowest to mature, requiring 8 to 10 years.
The mature seeds weighing are the world's heaviest. and on occasion as long as .
It is the slowest growing of all large trees, although some small to medium-sized desert trees are slower. At the Peradenaya Royal Botanic Gardens, it grew an average of per year over a period of 40 years.
The female flowers are the largest of any palm, up to diameter.
The male catkins, up to in length, are the longest known.
The leaves of Lodoicea have the longest lifespan of any monocot, nine years to develop in the terminal spike, and then nine more years as a fully functioning leaf. However, adult Lodoicea can have as many as twenty leaves with a potential lifespan of 24 years.
Finally, Lodoicea is the most efficient plant known at recovering nutrients from moribund leaves.

Of the six endemic palms in Seychelles, it is the only dioecious species, with male and female flowers on different plants.

Habit

L. maldivica 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 in diameter and deep, 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; they are partially elastic, 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 diameter 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.

Inflorescence

right|thumb|Male inflorescence

The inflorescences are interfoliar, lacking a covering spathe and shorter than the leaves. The staminate inflorescence is catkin-like, one to two metres long by about in width and produces pollen over a period of 8 to ten years. These catkins are generally terminal and solitary, but 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.

Habitat

Lodoicea maldivica inhabits rainforests where there are deep, well-drained soils and open exposed slopes; although growth is reduced on such eroded soils.

Phylogeny

Despite the proximity of the Seychelles to Africa, the broader diversity of palm life on the islands are considered to be slightly closer phylogenetically to that of south Asia; A genetic sequencing study of Lodoicea and other palms showed similarity between south Asiatic palms and Lodoicea. Lodoicea is one of four genera in the Lataniieae subtribe of the tribe Borrassae, and sequencing found them to be very closely related to Borassus and Borassodendron, although notably the phylogenetic placement of Lodoicea was among the least confident. thus this study provided genetic evidence for the suspected close relationships between Lodoicea and south Asian palms.

Dispersal

Genetic similarity between Lodoicea and south Asian palms, despite their geographical distance, raises questions about ancestral historical dispersal of Lodoicea to the Seychelles; and this natural history of Lodoicea is further obscured by the geology of the Seychelles, as the entirety of the archipelago (excluding some Pleistocene and coral reef formations) is composed of non-fossiliferous rock. Divergence between the palm populations would then follow from the isolation of the archipelago from the rest of Gondwonaland. Evidence suggests at least a proportion of the diversity of Flora on the islands are of "very ancient origin", Agricultural surveys of the Seychelles tend to categorize the islands as having very shallow, nutrient-poor soils, and the life-cycle of the coco de mer often involves a very long period of subterranean transversal of the primary apical shoot after fertilization and excision from the parent tree, wherein the growing plant cannot use solar radiation to undergo photosynthesis, These facts may jointly act as evolutionary incentives for the development of large, nutrient rich fruit, to feed the growing plant and increase likelihood of successful reproduction.

Competition may also be the driving factor in the evolution of the size of Lodoicea fruit. One hypothesis asserts that competition between parent tree and its progeny, as well as competition between sibling offspring, drove the large size of the coco de mer fruit. The hypothesis suggests that because coco de mer fruit fall directly at the base of their parental tree, there is strong competition between parent and offspring for resources, within which the already-established parent tree has a large asymmetric advantage. Furthermore, as the number of offspring produced by a specific parent increases, the number of individuals growing its immediate surroundings increases, and thus the competition for resources between its offspring worsens. Therefore, there exists a selective pressure favouring the production of fewer offspring, each with a maximal chance of successfully reaching adulthood conferred by large energy reserves in the fruit.

Until the true source of the nut was discovered in 1768 by Dufresne, 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 polished and decorated with valuable jewels as collectibles for their private galleries. The coco de mer tree is now a rare and protected species.

Uses

right|thumb|Tree in a Sri Lanka botanic garden

The species is grown as an ornamental tree in many areas in the tropics (including, for example, botanical gardens in Sri Lanka and Thailand), and subsidiary populations have been established on Mahé and Silhouette Islands in the Seychelles to help conserve the species.

The seeds of Lodoicea have been highly prized over the centuries; their rarity caused great interest and high prices in royal courts, and the tough outer seed coat has been used to make bowls such as for Sufi/Dervish beggar-alms kashkul bowls and other instruments. The history of exploitation continues today, and the collection of nuts has virtually stopped all natural regeneration of populations with the exception of the introduced population on Silhouette. This palm has been lost from the wild from three Seychelles islands within its former range. The main populations of Lodoicea maldivica are found within the Praslin and Curieuse National Parks,

Gallery

File:Keskul GrantBowl.JPG|Sufi kashkuls were often made from a coco de mer which would be difficult to find for ordinary beggars.

File:Kashkul, or Beggar’s Bowl, with Portrait of Dervishes and a Mounted Falconer, A.H. 1280.jpg|Kashkul with portrait of dervishes and a mounted falconer, A.H. 1280. Brooklyn Museum.

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