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Phylloxylon xylophylloides (Baker) Du Puy, Labat & Schrire

Protologue
Kew Bull. 50(3): 489 (1995).
Family
Papilionaceae (Leguminosae - Papilionoideae, Fabaceae)
Synonyms
Phylloxylon ensifolium Baill. (1896).
Origin and geographic distribution
Phylloxylon xylophylloides is endemic to Madagascar, where it mainly occurs on the upper slopes of the eastern margin of the Central Plateaux over nearly the whole length of the island.
Uses
The wood, known as ‘harahara’ or ‘arahara’, is traditionally used for house construction, furniture, agricultural implements and tool handles, but it is also suitable for long-lasting poles, heavy-duty flooring, turnery and novelties. It is used as fuelwood and for making charcoal.
A decoction of the twigs is used in traditional medicine as a tonic, and to treat fever and skin complaints. The leaves are credited with stimulant, digestive and febrifugal properties, the roots with depurative activity. The wood is used as fish poison, and a maceration of the wood is used against a poisonous water beetle (‘tsingala’).
Properties
The heartwood is dark reddish brown and distinctly demarcated from the yellowish grey to brownish grey sapwood. The grain is straight or wavy and interlocked, texture very fine.
The wood is very heavy, with a density of about 1200 kg/m³ at 12% moisture content. The wood dries slowly, planks 25 mm thick can be dried in 3–4 months under high plateau conditions without twisting, splitting or deformation. Shrinkage rates from green to oven dry are high: 6.3% radial and 11.2% tangential. Once dried, the wood is very stable in service. The wood is very hard and elastic. At 12% moisture content, the modulus of rupture is about 260 N/mm², modulus of elasticity 15,500 N/mm², compression parallel to grain 105 N/mm² and Chalais-Meudon side hardness 19.7.
Sawing and working of the wood is difficult, and the use of stellite teeth and tungsten carbide tools is necessary. The wood holds nails and screws well, but pre-boring is necessary. Gluing is difficult but varnishing and waxing properties are good. The wood is very durable and extremely resistant to impregnation.
Botany
Leafless shrub or small tree up to 15(–20) m tall; bole up to 35(–50) cm in diameter; bark pale brown, flaking off in fibrous pieces; stems flattened, thinly leathery, glossy green, much-branched, internodes leaf-like, elliptical to narrowly elliptical, 3–20 cm × 0.5–3.5 cm, with buds along the margins, glabrous except for the buds; older stems becoming rounded. Inflorescence a few-flowered raceme produced from the buds on the leaf-like stem margins, 3–8 (–18) mm long; bracts numerous on the axis, broadly ovate. Flowers bisexual, papilionaceous; pedicel 2–5 mm long; calyx shallowly cup-shaped, c. 2 mm long, with short teeth, minutely brown hairy; corolla pink to pale purple, with elliptical standard c. 8 mm long, with white or greenish basal spot, wings and keel c. 10 mm long; stamens 10, 9 united into a long sheath c. 8 mm long and 1 free; ovary superior, narrowly oblong to linear, style curved upward. Fruit a spindle-shaped pod 2.5–4.5 cm × 1.5–2 cm, with beak at apex, leathery, greenish, glossy, eventually dehiscent, 1(–2)-seeded. Seed ovoid, with thin seed coat. Seedling with epigeal germination; hypocotyl curved; cotyledons completely fused to a homogeneous mass.
Phylloxylon xylophylloides shows a peculiar germination. A plumule is absent in the seed. The radicle penetrates into the soil while the seed remains at its position on top of the soil. In 3–4 months the seedling develops a spindle-shaped primary root 10–15 cm long and a curved hypocotyl. At this stage the cotyledonous mass of the seed has been much reduced, and the seedling enters into a resting period until the onset of the next rainy season. Then a leaf-like stem develops from a bud on the hypocotyl. The growth is very slow. Phylloxylon xylophylloides usually flowers from August to November and March to April.
Phylloxylon comprises 7 species, all endemic to Madagascar. It belongs to the tribe Indigofereae, in which it is considered to be basal because it shows many primitive character-states. The leaf-like young stems are characteristic in 4 species, but the other 3 have narrow and rounded young stems.
Phylloxylon arenicola Du Puy, Labat & Schrire from north-eastern Madagascar is a shrub or small tree up to 4 m tall with bole up to 15 cm in diameter. It does not have leaf-like stems and has obovate leaves. Its wood is heavy and extremely durable, and the stems are used for house posts, which may last for up to 100 years. A leaf decoction is used in rituals.
Ecology
Phylloxylon xylophylloides occurs in humid, evergreen forest, often along water courses, usually at 600–1600 m altitude, but descending to sea-level in the south-eastern part of Madagascar. It is found on laterite and sandy soils.
Management
The seeds remain viable for up to 6 months. Trees are difficult to fell with traditional equipment because of the very hard wood.
Genetic resources and breeding
Phylloxylon xylophylloides is classified as vulnerable in the IUCN Red list. Although it is widespread in eastern Madagascar, its distribution area is discontinuous and many larger populations are threatened by forest clearing, e.g. for titanium mines, and selective felling for its timber. All other Phylloxylon species are classified as endangered or even critically endangered.
Phylloxylon xylophylloides shows significant genetic variation, particularly in the shape of the leaf-like stems and the length of the staminal sheath, which differ between northern, central and southern populations.
Prospects
The prospects for Phylloxylon xylophylloides and other Phylloxylon species as timber trees of commercial importance are very poor because of the often small size of the bole, their uncommon occurrence and their slow growth. Locally, they will remain important for the production of durable posts and implements. However, attention should be given to adequate protection.
Major references
• Boiteau, P., Boiteau, M. & Allorge-Boiteau, L., 1999. Dictionnaire des noms malgaches de végétaux. 4 Volumes + Index des noms scientifiques avec leurs équivalents malgaches. Editions Alzieu, Grenoble, France.
• du Puy, D.J., Labat, J.N., Rabevohitra, R., Villiers, J.-F., Bosser, J. & Moat, J., 2002. The Leguminosae of Madagascar. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 750 pp.
• du Puy, D.J., Labat, J.N. & Schrire, B.D., 1995. A revision of Phylloxylon (Leguminosae: Papilionoideae: Indigofereae). Kew Bulletin 50(3): 477–494.
• Guéneau, P., Bedel, J. & Thiel, J., 1970–1975. Bois et essences malgaches. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 150 pp.
• Peltier, M., 1971. Singularités de la graine et de la plantule chez Phylloxylon ensifolium H. Baill. (Papilionacées). Adansonia, ser. 2, 10(4): 533–535.
Other references
• Debray, M., Jacquemin, H. & Razafindrambao, R., 1971. Contribution à l’inventaire des plantes médicinales de Madagascar. Travaux et Documents No 8. ORSTOM, Paris, France. 150 pp.
• du Puy, D. & Labat, H., 1998. Phylloxylon xylophylloides. In: IUCN. 2007 Red list of threatened species. [Internet] http://www.iucnredlist.org. Accessed January 2008.
• Guéneau, P., 1971. Bois de Madagascar. Possibilités d’emploi. Centre Technique Forestier Tropical, Antananarivo, Madagascar. 75 pp.
• Kerharo, J., Guichard, F. & Bouquet, A., 1961. Les végétaux ichtyotoxiques (poisons de pêche), 2ème partie : inventaire des poisons de pêche. Bulletins et Mémoires de l’École Nationale de Médecine et de Pharmacie de Dakar 9: 355–386.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
Author(s)
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article:
Lemmens, R.H.M.J., 2008. Phylloxylon xylophylloides (Baker) Du Puy, Labat & Schrire. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.