Difference between revisions of "Voanioala gerardii"

Robust solitary, monoecious, palm. TRUNK 15-20 m tall, basally with a large root boss to about 1 m in diam., about 35 to 40 cm in diam. head high, distally the stem bare, very conspicuously "stepped" and ringed with oblique leaf scars about 10 cm distant, the distal part of the internode projecting about 5 cm outwards from the proximal part of the following internode. LEAVES about 15-20 in the crown, about 5 m long, cleanly abscising; leafsheath tubular at first, fibrous, apparently soon disintegrating to leave a massive elongate rectangular leaf base, forming an apparent petiole about 150 x 30 cm, about 8-10 cm thick, with sparsely fibrous margins, abaxially densely covered with caducous brown indumentum; leaf base suddenly contracting into rachis, true petiole absent, the rachis ; ± rectangular in cross section in the mid-leaf region, 4 x 3 cm, abaxially densely covered with caducous brown indumentum as the leaf base; leaflets about 70 on each side of the rachis, regularly arranged, rather stiff, scarcely pendulous, very coriaceous, concolorous, shining mid green when fresh, drying pale, mid-leaf leaflets about 150 x 7 cm, unevenly bilobed at the tips, mid vein prominent adaxially, abaxially bearing a few brown ramenta near the base, about 8 longitudinal veins besides the mid vein, transverse veinlets obscure but lamina minutely transversely striate, portion of leaflet exposed in the sword leaf bearing caducous chocolate scales, thin wax also present on both surfaces. INFLORESCENCES to about 1.5 cm long, interfoliar, erect in bud, later horizontal; peduncle about 90 cm long, circular in cross section, 4-5 cm in diam., pale cream-coloured at anthesis, becoming green in fruit, brown scaly when newly emerged; prophyll tubular, 2 keeled, about 70 x 13 cm, fibrous, remaining hidden among the leaf bases, bearing caducous brown scales; peduncular bract about 120 x 18 cm, bright green and strictly tubular in bud, later splitting longitudinally, flattening and becoming somewhat cowl-like, abaxially deeply and closely longitudinally grooved, bearing scattered brown scales on the ridges between the grooves, adaxially smooth, glabrous, pale cream-coloured; rachis about 60 cm long; rachillae about 60, those near the base longest, to about 50 cm, decreasing in length towards tip of inflorescence, most with a basal bare portion 2-5 cm long, about 7 mm in diam. near the base, decreasing to 1.5 mm in diam. near the tip, the rachillae bearing 0-7 triads near the base and paired or solitary staminate flowers distally, the flower groups spirally arranged, or becoming somewhat distichous by close-packing, about 5-10 mm apart. STAMINATE FLOWERS asymmetrical, broadly or narrowly triangular in outline, about 10-12 x 7-9 mm, creamy-yellow just before anthesis, the whole inflorescence smelling sweetly; sepals about 3-4 x 4 mm, distinct, slightly to strongly imbricate at the base, triangular, acute to acuminate, membranous, glabrous; petals 9-19 x 3-6 mm., unequal, glabrous, thinly coriaceous except at the thick angular tips, broadly and irregularly triangular-ovate, with acute or acuminate tips, abaxially smooth, adaxially marked with the impressions of the stamens and papillose near the thick tips; stamens with filaments subulate, 0.5-2.5 x 0.1 mm, anthers 9 x 1 mm, basifixed, basally sagittate, apiculate at the tips, latrorse. PISTILLATE FLOWERS only known as buds, irregularly triangular, about 18 x 10 mm; sepals 8-12 x 10 mm, unequal, strongly imbricate, broadly ovate, with triangular, keeled tips, coriaceous, glabrous, the margins minutely toothed; petals 15 x 8 mm, basally irregularly imbricate, conspicuously valvate at the triangular tips, abaxially with scaly indumentum towards the apex, adaxially strongly papillose towards the tip; staminodial ring about 1.2 mm high with 9 irregular, triangular teeth, 0.1-0.5 mm; gynoecium about 4 mm in diam. FRUIT green when immature, turning rich red-brown when ripe, 7-8 x 4-5 cm, covered with dense chestnut-brown scaly indumentum, one-seeded, somewhat irregularly ellipsoid, tipped with a short beak and stigmatic remains; epicarp purplish-brown, densely covered with brown scaly indumentum; mesocarp with an outer fibrous zone just below the epicarp, and an inner fleshy zone; endocarp ellipsoid, apically pointed, basally truncate, very heavily thickened, pale brown when fresh, becoming grey with age, very deeply and irregularly longitudinally grooved, with 3 very deep basal impressions each with a central germination pore, in section the body of the endocarp traversed by longitudinal irregular vertical canals and fibres, inner surface of the endocarp with numerous irregular rounded excrescences intruding into the cavity. SEED irregularly ellipsoid, 4 x 2 cm, filling the endocarp cavity, laterally attached with a narrow irregular hilum, endosperm homogeneous but irregularly intruded by the endocarp protruberances, very hard, white, with a narrow, irregular central lacuna. EOPHYLL and leaf 2 entire, lanceolate, about 30 x 7 cm, leaves 3 and 4 bifid. (J. Dransfield and H. Beentje. 1995)/Palmweb.

This is a monotypic genus.

An extraordinary palm, occurring as scattered trees in the depths of the forested Masoala Peninsula. The discovery of the palm and the first scientific collection are described in Dransfield (1989b, 1992b). The forest coconut is a robust palm with a conspicuously "stepped" trunk. Endocarps and partially rotted fruit carpet the ground beneath the only mature trees known, and as seedlings have not been observed away from the base of the trees, it seems that there is little effective dispersal at the present day. As in Satranala decussilvae, we suggest that the extraordinarily hard sculptured endocarp is an adaptation by a now extinct animal, such as the elephant bird, Aepyornis. Seed collected in October 1986 germinated at Kew in February 1987. From this batch of seedlings, Margaret Johnson (1989) counted the chromosomes of Voanioala, and discovered that there are at least 596 chromosomes. This quite extraordinary number, at that time the highest recorded not only in the palms, but in all the monocotyledons, this has been confirmed by RŮser (1994) who counted over 600 in another sample from the same batch of seed, grown at Fairchild Tropical Garden in Florida. The genus is named after the local name, while the specific epithet honours Jean Gerard, one of the discoverers. (J. Dransfield and H. Beentje. 1995)/Palmweb.

Conservation: Critical. Voanioala gerardii seems to be a very rare palm; less than ten trees are known to exist in the wild. Unless the superb primary rain forests of the Masoala Peninsula can be effectively protected against further destruction, and palms in particular safeguarded from destructive exploitation for palm cabbage, then the chances of survival for this remarkable and beautiful palm are slim indeed. Forest coconuts are cut down for their edible palm hearts and the seeds are also harvested for trade. Only 10 mature trees are known and such a small population is inherently vulnerable to any chance event that may occur. These trees are also vulnerable due to the current limited dispersal of their seeds. The forest coconut is found within an area of the Masoala Peninsula that has recently been declared a National Park; the survival of the species will depend largely on the effectiveness of this park.

The Forest Coconut, Voanioala gerondii, is a slow-growing palm from the family Arecaceae, discovered and described in 1989 as the only species in genus Voaniala. Endemic to the Northeast of Madagascar, it currently occurs only in three separate locations in swampy valleys and on low hills (up to an elevation of 450 meters) in palm dominated rain forest around the Bay of Antongil, largely in Parc National de Masola. The Forest Coconut is a massive palm that grows to 15-20 meters tall. The crown is composed of 15-20 bracts, each about 5 meters long. Up to 60 flower stalks develop at a time, and bear mature fruit that is about 8X5 cm, and red-brown when mature. Fruit accumulate under the tree, indicating that animals or birds that once acted as dispersal agents may have become extinct. The thick, hard endocarp suggests that animals involved in dispersal would need special adaptation for opening the fruit, such as the extinct elephant bird (Aepyornis). The fruit are attractive to illegal seed collectors, and the edible palm heart is also desirable; harvesting of this species in addition to habitat loss to agriculture and logging has reduced the number of mature individuals to about 15-30 trees total. The IUCN recognizes V. gerondii as critically endangered, and it is included as one of the world’s 100 most endangered species in a report submitted by the IUCN and the Zoological Society of London in 2012. (Baillie and Butcher 2012; Dransfield 1989; Dransfield and Beentje 1995; Dransfield et al. 2006; Dransfield and Rakotoarinivo 2011)

Study of seedlings germinated from isotypes held in the Kew Living Collections Department show that V. gerondii has a mitotic index much larger than other palms and shows rapid root growth, although seedlings are reported to grow very slowly. Their seeds are banned from export; few individuals are cultivated outside of Madagascar. V. gerondii is polypoid (uncommon for palms) and has a chromosome count far larger than most palms (with a diploid number more than 550, as compared to other polyploid palms reported between 2n=64-200). Its chromosomal number may be one of the highest known chromosome numbers for angiosperms in general. It is thought to be closely related to Jubaeopsis caffra, a diploid palm native to the Eastern Cape of South Africa, thus may have diverged from a polyploid ancestor before the separation of Madagascar from the African continent. The Forest Coconut also has a close relationship with the modern coconut, Cocos nucifera. (Baillie and Butcher 2012; Dransfield 1989; Dransfield and Beentje 1995; Dransfield et al. 2006; Dransfield and Rakotoarinivo 2011)

This species is thought perhaps to have been the ancestor of the coconut that we know today. Even though the nut only measures about 5 cm x 7 cm and weighs approximately 100 - 120 grams, the close relationship with the modern coconut, Cocos nucifera, can be observed in the similarities of the arrangement of the inflorescences and in the physical structure of the fruits (nuts). One feature of this palm is the large number of chromosomes its cells contain, at around 600 this is the largest number ever recorded for a monocotyledon.

"A very slow and VERY rare palm from Madagascar. It seems to be the closest relative to the modern coconut, but has an unbelievably large number of chromosomes (so hybridization with the coconut is not likely). Seed has been banned from exportation for some time now, so it is increasingly hard to acquire a specimen. It appears to have a little more cold tolerance than the coconut (though not the cool tolerance that would be needed to grow it in California), but there's no way I'm going to put either of mine through less than 40F. The grower who had them before me got down to 29F and they don't have any damage, so I think the hardiness thing may be true, but they wouldn't recover from damage as fast as a coconut can. For me they are one of my slowest palms, growing at about the speed of a Howea forsteriana (sending out maybe 2-3 leaves per year in optimal conditions), so don't expect this palm to rocket towards the sky like it's coconut relative. The largest one currently appears to be the one at the Sullivan garden in Hawaii, which is maybe 8-10 feet overall. If you grow one and live to see it set seed, consider yourself a lucky person. It's a beautiful adult however, looking like an extra lush coconut with notches on it's trunk (hard to describe, I'll upload a picture), so I think that the negatives pale in comparison to the possible positives of having an adult plant." (Keith Zimmerman)