Ravenea lakatra
Ravenea (rah-vehn-EH-ah) lakatra (lah-KAHT-rah) | |||||||
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Photo by Dr. Charles Rakotovao, MBG-Madagascar/Royal Botanic Gardens, Kew. Uploaded by Dr. Romer Rabarijaona (curator), Kew, Madagascar Conservation Centre. | |||||||
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Contents
Habitat and Distribution
Endemic to east Madagascar, from between Masoala and Vangaindrano. Moist lowland forest on slight mid slope or ridge crest; alt. 90-850 m. Ravenea lakatra Occurs in moist lowland forest on slight mid slopes or ridge crests from 50 to 1,200 m.Description
Moderate-sized solitary palm. TRUNK 4.5-14 m high, 13-17 cm in diam., to 11 cm across near the crown; nodal scars about 1 cm (to 3.5 cm near crown), internodes 10-16 cm (about 2 cm near crown), light brown; wood very hard, with black fibre layer; sheath remnants clothing distal part of trunk; short, erect woody sheath base remnants set at nodes over the whole length of trunk, very hard, to 7 cm long; base of crown about 22 cm across. LEAVES 8-10 in the crown, porrect, slightly arching, held on edge in distal part of leaf; sheath 75-80 x 16 cm, with down-pointing fibres on margins, white-tomentose, with black internal fibres; petiole 80-160 cm, proximally 5-6 x 3-6 cm across, distally 4 x 3 cm across, channelled, with very sharp (almost sawtooth) edges, proximally closely den- ticulate, with white or grey tomentum but glabrescent; rachis 2.3-3.5 m, in mid-leaf 1.2-2.2 x 1.3 cm, with white to grey tomentum but quickly glabrescent; leaflets stiff, in one plane, mid-green, 87-98 on each side of the rachis, the proximal 42-102 x 0.8-3.8 cm, the median 66-77 x 2.7-4.7 cm (interval 3-4 cm), distal 23-49 x 0.7-2.3 cm, few small ramenta near the rachis, but these deciduous, sinuous transverse veinlets clearly visible. STAMINATE INFLORESCENCE interfoliar, solitary, branched to 1 order (only seen as dead); peduncle not seen; prophyll not seen; peduncular bracts seen 89, 103 cm; rachis about 92 cm; rachillae 6-30 cm, 1-1.5 mm across; pedicel 1.2-1.6 mm. STAMINATE FLOWERS with the calyx connate for 1 mm, with free lobes 0.8 x 0.2-0.3 mm; petals probably connate for 1.8 mm, free lobes 5-5.5 x 1.3 mm; stamens ? in 2 series, the epipetalous ones adnate for/inserted at 2.2-2.5 mm, the filaments absent, the anthers 1.5 x 0.5 mm. PISTILLATE INFLORESCENCE solitary, erect, interfoliar among old leaf bases in fruit, branched to 1 order; peduncle 82-130 cm, proximally 3.5-4 x 1.5-2 cm, distally 2.5 x 1.5 cm, densely white-brown pubescent; prophyll 10-25 x 5 cm, tattering, white, membranous; peduncular bracts 20-43 cm, 30-40 cm (inserted at 22-24 cm from the base of the peduncle), 140 cm (inserted at 48 cm), 88-119 cm (inserted at 60-87 cm), all densely white- to brown-pubescent abaxially, glabrous adaxially; rachis 44-86 cm, white-tomentose, with 50-70 porrect rachillae; rachillae 7-65 cm, 2 mm across, sinuous, proximally 11 x 5 mm; pedicels 3-6 mm; bracteole 1.5 x 1.5 mm, connate for up to 1 mm. PISTILLATE FLOWERS with the calyx connate for 2-2.5 mm, 3.5 mm across, the free lobes 0.8-2 x 0.9-1.2 mm; petals 5-8 x 2.5-5.5 mm. FRUIT blackish, slightly depressed globose, 15-20 x 18-21 mm, with terminal stigmatic remains, 1-/2/3-seeded; each seed with sclerified layer 8-11 mm and 6-10.6 mm across with sharp distal acumen 2.5-3 mm, the layer 0.3-0.35 mm thick. SEED 9-10 mm, 5-10 mm across, with distal acumen of 1.5 mm; seedcoat black, 0.2 mm thick. (J. Dransfield and H. Beentje. 1995)/Palmweb. Editing by edric.
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Dioecious, medium-sized palm with solitary trunk 4.5–14 m tall and 13–17 cm in diameter at breast height, with a layer of black fibres in the outer part of the stem, the nodes over the whole length of the trunk set with up to 7 cm long woody leaf sheath base remnants; crown shaft absent. Leaves 8–10 in crown, spirally inserted, pinnately compound, slightly arching; sheath 75–80 cm long, with downward-pointing fibres on the margins, densely white-hairy, with black internal fibres; petiole 80–160 cm long, channelled with very sharp edges, with white or grey hairs but glabrescent; rachis 2.5–3.5 m long, with white or grey hairs but glabrescent; leaflets 87–98 on each side of the rachis, in one plane, stiff, medium green, with sinuous transverse veins connecting the longitudinal veins, basal leaflets up to 102 cm long, median leaflets up to 77 cm long, upper leaflets up to 49 cm long. Inflorescence unisexual, solitary, between the leaves, branching to 1 order; male inflorescence with rachis c. 92 cm long, branches up to 30 cm long; female inflorescence erect, peduncle 82–130 cm long, bracts up to 140 cm long, rachis 44–86 cm long, with 50–70 branches up to 65 cm long, white hairy. Flowers unisexual, 3-merous; male flowers with sepals connate for 1 mm, stamens 6, in 2 series, pistillode short, with rudimentary locules and ovules; female flowers with calyx connate for 2–2.5 mm, staminodes 6, with sterile anthers, gynoecium with 3 unilocular carpels, stigmas 3. Fruit a slightly depressed globose drupe 15–20 mm × 18–21 mm, blackish, with terminal stigmatic remains, 1–3-seeded. Seed 9–10 mm × 5–10 mm, black, with distal acumen 1.5 mm long. (PROTA) The type and the material found much further south agree perfectly as for the leaf and inflorescence details. The Flora (Jumelle & Perrier 1945), but not the protologue, describes the tree as being 15-30 m high, and with a diameter of 15-30 cm, while the wood is described as white and soft. We treat these later additions with suspicion. The seed is unique within the genus in having a sharp pointed apex. (J. Dransfield and H. Beentje. 1995)/Palmweb. |
Culture
Cold Hardiness Zone: 10a
Comments and Curiosities
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This is a dioecious genus. This species can be recognized immediately by the woody "steps" on its trunk - actually remains of the leaf sheaths. All woody parts of this species are rock-hard. The scientific name is taken from the local name. (J. Dransfield and H. Beentje. 1995). Conservation: IUCN Red List 2012 - Critically Endangered. The palm has a large distribution range (extent of occurrence is over 58,000 km²) but it is not common in any of the current known sites. The population is estimated to only number 30 mature trees. The leaves of this species are exploited by local people for weaving hats and individual palms may be pruned into juvenility by constant harvest of the emerging leaves. This species is listed as Critically Endangered based on the small population size, this is a genuine deterioration since the 1998 listing of Endangered. This species has an extremely wide range but at each of the known sites there are only a few individuals. The population is estimated to number fewer than 30 mature trees. The population is declining. The main threats to this species are habitat loss through clearance for shifting agriculture and logging and harvesting of the leaves to be used in weaving. Excessive harvesting impacts the reproductive output of the species. Protected in Masoala, Makira and Andasibe. Regulation and monitoring of the harvest may be required. (Rakotoarinivo, M. & Dransfield, J. 2012) Uses: At Andasibe extensively used as a source of fibre for weaving high-quality hats, the young leaves being harvested; this prevents the trees from growing, and most populations are pruned to a perpetually juvenile rosette stage. The leaves are harvested and used for weaving hats and other handicrafts. Ravenea lakatra is easily recognized by the woody ‘steps’ (remains of the leaf sheaths) on the trunk, and within the genus it is the only Ravenea species with acuminate seeds. (PROTA) Phenology: In the Manombo region (south-eastern Madagascar) Ravenea lakatra flowers in July–September, and fruits in October–February. (PROTA) Management: The harvesting of young leaves for weaving prevents the palms from growing, and in practice most populations are pruned to a perpetually juvenile rosette stage. (PROTA) Genetic resources and breeding: Ravenea lakatra is classified as endangered in the IUCN Red list, as it occurs in low numbers in few locations, several of which are being destroyed rapidly. The population at Mantady consists of pruned rosettes only. (PROTA) Prospects: As Ravenea lakatra is an endangered species, in-situ and ex-situ conservation activities are of the highest importance. In its current area of distribution exploitation of this species should be made sustainable. Introduction into other locations such as botanical gardens and reforestation sites should be encouraged, and supported by research on appropriate propagation and management practices. (PROTA) In its native Madagascar, this palm carries the name Tsilanitafika, which, in English, means "cannot be cut down by an Army," as the trunk of this palm is so extraordinarily durable. It is rather slender and can reach up to about 14 m (47 ft.) tall and carries an upright crown of pinnate leaves that arch slightly towards the tip. It is now endangered in its native home by forest destruction and overexploitation of its leaves as a source of fiber. The few remaining populations in the rainforests on the eastern side of the island only have a small number of mature trees still remaining. (RPS.com) "Lakatra is among or the rarest of Raveneas, not much left in it's native Madagascar due to overharvesting for the trunk( for what it's also named Ironwood palm) Very rarely seen outside some nature reserve in Madagascar. Also a very usefull palm for it's leaves for fine artisanal handicrafts hat , basket and other stuffs , also one of the reason of it's almost extintion.It is rather found in rainforest and prefer humid and much water. Sometimes can be found in nursery in Mauritius. A good indoor and pot plant when young." (timrann, Mauritius Island 2007) This is a tillering palm, it exhibits saxophone style root growth (it has a heel), keep top third of heel above soil elevation! |
External Links
- Glossary of Palm Terms
- MODERN BOTANICAL LATIN
- "Just To Be Clear"
- THE SAXOPHONE STYLE ROOT GROWTH (HEEL)
References
Phonetic spelling of Latin names by edric.
Special thanks to Geoff Stein, (Palmbob) for his hundreds of photos.
Special thanks to Palmweb.org, Dr. John Dransfield, Dr. Bill Baker & team, for their volumes of information and photos.
Glossary of Palm Terms; Based on the glossary in Dransfield, J., N.W. Uhl, C.B. Asmussen-Lange, W.J. Baker, M.M. Harley & C.E. Lewis. 2008. Genera Palmarum - Evolution and Classification of the Palms. Royal Botanic Gardens, Kew. All images copyright of the artists and photographers (see images for credits).
Dransfield, J. & Beentje, H. 1995. The Palms of Madagascar. Royal Botanic Gardens, Kew and The International Palm Society.
Many Special Thanks to Ed Vaile for his long hours of tireless editing and numerous contributions.