Difference between revisions of "Voanioala gerardii"

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• SUB CATEGORY PALMS OF MADAGASCAR

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Voanioala gerardii
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Scientific Classification
Genus: Voanioala Species: gerardii
Synonyms
None set.
Native Continent
Africa
Morphology
Habit: Clustering Leaf type: Pinnate
Culture
Survivability index
Common names
Voa-nio-ala (forest coconut, Betsimisaraka).

Habitat and Distribution

Endemic to Madagascar, Masoala Peninsula. Primary forest rich in palms and pandans in swampy valley bottom and on gentle slopes at about 400 m. alt.

Description

Robust solitary unarmed pleonanthic monoecious tree palm. TRUNK 15-20 m tall, basally with a large root boss to c. 1 m diam., c. 35 cm diam., distally the stem bare, very conspicuously "stepped" and ringed with oblique leaf scars c. 10 cm distant, the distal part of the internode projecting c. 5 cm outwards from the proximal part of the following internode. LEAVES c. 15-20 in crown, c. 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 c. 150 x 30 cm, c. 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 c. 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 c. 150 x 7 cm, unevenly bilobed at the tips, mid vein prominent adaxially, abaxially bearing a few brown ramenta near the base, c. 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 c. 1.5 cm long, interfoliar, erect in bud, later horizontal; peduncle c. 90 cm long, circular in cross section, 4-5 cm diam., pale cream-coloured at anthesis, becoming green in fruit, brown scaly when newly emerged; prophyll tubular, 2keeled, c. 70 x 13 cm, fibrous, remaining hidden among the leaf bases, bearing caducous brown scales; peduncular bract c. 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 c. 60 cm long; rachillae c. 60, those near the base longest, to c. 50 cm, decreasing in length towards tip of inflorescence, most with a basal bare portion 2-5 cm long, c. 7 mm diam. near the base, decreasing to 1.5 mm 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, c. 5-10 mm apart. STAMINATE FLOWERS asymmetrical, broadly or narrowly triangular in outline, c. 10-12 x 7-9 mm, creamy-yellow just before anthesis, the whole inflorescence smelling sweetly; sepals c. 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, c.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 c. 1.2 mm high with 9 irregular, triangular teeth, 0.1-0.5 mm; gynoecium c. 4 mm 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, c. 30 x 7 cm, leaves 3 and 4 bifid. (J. Dransfield and H. Beentje. 1995)

Culture

Comments and Curiosities

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, 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.

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.

Uses: Cut for palm-heart.

External Links

• Glossary of Palm Terms
• Pronunciation Key

References

Special thanks to Geoff Stein, (Palmbob) for his hundreds of photos, edric.

Many Special Thanks to Ed Vaile for his long hours of tireless editing and numerous contributions.