| Voanioala | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Arecales |
| Family: | Arecaceae |
| Subfamily: | Arecoideae |
| Tribe: | Cocoseae |
| Subtribe: | Attaleinae |
| Genus: | Voanioala J. Dransf. |
| Species: | V. gerardii |
| Binomial name | |
| Voanioala gerardii J. Dransf. | |
Voanioala gerardii, commonly known as theforest coconut, is a species offlowering plant in the familyArecaceae. It is a relative of thecoconut, and is generally regarded asmonotypic within the genusVoanioala. However, a team of geneticists headed by Bee F. Gunn found sufficient genetic variation withinVoanioala to constitute at least two and possibly four cryptospecies.[3]Voanioala isendemic toMadagascar, and is threatened byhabitat loss.Voanioala is harvested for its edible seeds and palm heart. It is estimated that there are fewer than 15 mature trees remaining.[1]
The forest coconut is a Madagascan tree that can reach 15–20 meters high in the wild. It is supported by a strong root base, and its leaves sprout from the crown. Voanioala can reach up to 5 meters in height. Theleaflets are waxy, green, and stiff, and seventy of them can grow from each side of a leaf. The fruit grows in groups at the crown with a thick reddish-brown color. Each seed is up to 2.8 inches (7 cm) long and 1.5 inches (3.5 cm) thick and is longitudinally grooved.[4] A scientifically remarkable trait is that each cell has about 600 chromosomes, which is extraordinary for amonocotyledon.[5]
The fleshy, fibrous fruit of these trees has a highly sculpturedendocarp (woody inner layer surrounding the seed), which has been suggested to be an adaptation to being swallowed and surviving thecrop ofelephant birds, an extinct group of large flightless birds formerly native to the island, as New Guinea palm fruit with similar features, belonging to the generaPtychococcus,Brassiophoenix andLicuala are readily eaten bycassowaries who serve as their major seed dispersers. The trees appear to lack effective living seed dispersers, and rotting fruit blankets the ground beneath the trees, with seedling seemingly unable to disperse significant distances away from mature trees.[6]
Voanioala gerardii is endemic to Madagascar, and is found in only theBay of Antongil of theMasoala Peninsula, in the northeastern area of the island. It is extremely rare.[1][5]
The forest coconut is found in the bottom of swampy valleys, as well as slopes inrainforests[5] at an elevation of 200–450 meters above sea level.[7]
Voanioala gerardii is critically endangered because of its scarcity. Only 10-15 trees are found. They are cut down for their edible palm hearts, and their seeds are used for market trade. They are also rare because of its poor dispersal of seeds. Habitat loss through agricultural logging threatens forest coconuts as well.[1] The national park in Masoala Peninsula protects the forest coconuts on its property, and its future depends greatly on the effort of the national park.[5] Its population is currently decreasing.[1]
We suggest the endocarp [ofSatranala decussilvae] may be adapted to being swallowed by large birds (such as the now extinctAepyornis) – a theory which, of course, cannot be tested. However, it is worth noting that very heavily sclerified and sculptured endocarps are found inPtychococcus andBrassiophoenix (Uhl & Dransfield 1987) and in two species of Licuala (M. Forrero, pers. comm.) in New Guinea, where they appear to be adapted to dispersal by cassowaries, extant relatives of the extinct Madagascar elephant bird ... As inSatranala decussilvae, we suggest that the extraordinarily hard sculptured endocarp [ofVoanioala gerardii] is an adaptation by a now extinct animal, such as the elephant bird,Aepyornis.
