Triplochiton scleroxylon

Triplochiton scleroxylon

The obeche (Triplochiton scleroxylon K. Schum.) is an arboreal species belonging to the Sterculiaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Plantae,
Magnoliophyta division,
Class Magnoliopsida,
Malvales Order,
Sterculiaceae family,
Genus Triplochiton,
Species T. scleroxylon.
The terms are synonyms:
– Samba scleroxylon (K.Schum.) Roberty;
– Triplochiton johnsonii C.H.Wright;
– Triplochiton nigericum Sprague.

Etymology –
The term Triplochiton comes from the union of the Latin word triplus, derived from tri, three and from chiton, neo-Latin derived from the Greek χιτών, khitōn, which means tunic, which is also the origin of the word chitin.
The specific epithet scleroxylon comes from the union of the terms sclero, in turn from the Greek σκληρός, hard and from ξυλον, xylon, wood; then with hardwood.

Geographic Distribution and Habitat –
Triplochiton scleroxylon is a plant native to western tropical Africa and present from Sierra Leone to Gabon, the Central African Republic and the Democratic Republic of the Congo.
This species is widely distributed in the forest zone of West and Central Africa from Guinea east to the Central African Republic and south to Gabon and the Democratic Republic of the Congo. It is commonly planted in its natural range (e.g. Ivory Coast, Ghana and Nigeria) and occasionally elsewhere, e.g. in the Solomon Islands.
Its habitat is that of the pluvial forests of western and central Africa and in particular of the semi-deciduous forests of the plain, also in abandoned cultivated lands in the transition zone between pluvial forest and semi-deciduous forest or, also, in old secondary forests.
In Nigeria it is almost exclusively limited to low- and medium-elevation wet forest areas. It is found up to 900 m altitude in regions with annual rainfall up to 3000 mm, but is most abundant at 200–400 m altitude and in areas with annual rainfall of 1100–1800 mm and 2 rainy seasons.

Description –
Triplochiton scleroxylon is a deciduous tree that reaches heights of even 50 m, with a dense and rounded crown, with heavy, slightly expanded branches.
The trunk is straight, often angular and strongly ridged, branchless up to 30 m; up to 150 (210) cm in diameter, with low to very high (up to 8 m) buttresses; the bark is 7–30 mm thick, gray to yellowish brown, smooth when young, becoming scaly with age, often with vertical lines of lenticels.
The leaves are alternate, simple; the stipules are linear, 2-4 cm long, initially deciduous and leaving annular scars; the petiole is 3–10 cm long; the lamina is palmate with 5-7 lobes, up to 20 cm long and wide, cordate at the base, lobes largely ovate or triangular, from obtuse to acute at the apex, brown in colour, hairy when young but soon becomes glabrous.
The inflorescences have an axillary or terminal panicle, up to 10 cm long, densely hairy; the bracts are about 0,5 cm long, early deciduous.
The flowers are bisexual, regular, 5-mer; the 3-4 mm long pedicel, articulated at the base; the sepals are triangular, about 7 mm long, brown, starry and hairy; the petals are largely obovate, about 1 cm long, of a pinkish white color but purple at the base, hairy and densely silky; androgynophore about 3 mm long, hairy; there are 30-40 stamens, connected to the base in pairs; the ovary is surrounded by 5 petal-like staminodes, made up of 5 free carpels, connate styles.
The fruit consists of 1–5 rhomboid nuts about 2 cm × 1 cm with a 4–6 cm × 1–2 cm large wing.
The seedling has epigeal germination; hypocotyl about 7 cm long, epicotyl 1.5–2 cm long; cotyledons leafy, rounded, 2.5–3 cm in diameter, with 3–5 veins from the base.

Cultivation –
Triplochiton scleroxylon is a deciduous tree common in western and central Africa. Its wood is also known as ayous.
This plant is characteristic of semi-deciduous forests, where it often grows in a gregarious manner, but can sometimes be found in clearings in dense evergreen forests and in dry forests. It prefers more fertile, well-drained, ferruginous soils with a light or medium texture and acid to neutral pH. It does not tolerate waterlogging and generally avoids swamps. It is a pioneer species that requires light. Seedlings can be very abundant in larger forest gaps and the tree is characteristic of secondary forest.
It is a major West African timber species which has unfortunately been heavily exploited in the wild and is now commonly planted as a timber crop within its native range and sometimes outside its range as well. The tree is also used topically for food and medicine.
As a widely distributed pioneer species it is not easily subject to genetic erosion, but in many regions within its range it is under severe pressure from overexploitation.
For its cultivation it should be remembered that, being a plant of the humid and lowland tropics, where it is found at altitudes of up to 900 metres, it grows better in areas where the annual daytime temperatures are between 24 and 30 °C, but it can tolerate 18-36°C.
It prefers an average annual rainfall between 1,600 and 2,400 mm, but tolerates between 1,000 and 4,000 mm, and also requires a sunny position.
It grows in the most well-drained, fertile soils and prefers a pH between 5.5 and 6.5, tolerating between 4.5 and 7.5.
It is a very fast growing plant. In natural conditions the seedlings can reach 15 meters in height and 15 cm in stem diameter after 4 years. The average annual diameter increase in the forest averages 1 cm, but average annual diameter increases of up to 2.5 cm have been recorded in Nigeria and up to 0.3 cm in the Central African Republic. In a 19-year-old plantation in Ghana with 600 stems/Ha, trees averaged 21.8 meters tall with a trunk diameter of 27 cm.
Propagation can be by seed which begins to germinate 1 – 2 weeks after sowing, but the germination rate is often low. The rate and speed of germination increases when seeds are pretreated by moistening between layers of moist cotton wool.
Fruits with wings removed are buried shallowly in pots, which are placed in the shade. Seedlings are transplanted when the first leaves appear. They are fragile and sensitive. These develop a taproot, often forked, with few lateral roots in the upper 15 cm of the soil. The taproot of a 2m high sapling can be 1m long.
1 – 3 year old seedlings, with the tops intact but the root system severely reduced to allow planting in 40cm × 40cm × 40cm holes, have been successful. However, it has also been observed that cutting the primary root for planting causes serious drawbacks; new roots are slowly formed, which makes the plant subject to parasitic attacks.
Fruits can be picked from trees while still green just before ripening. Fruits stored at 18°C fully retained their vitality for 18 months. However, at 25°C the viability drops from about 80% to 15% after 6 months.
More than 50% of the seeds can still germinate after being stored for 7.5 years in sealed containers at 4°C.
Propagation can also take place by cuttings. Single node cuttings with one leaf have been successfully rooted under fog; rooting was improved by hormone treatment and a high bed temperature of 30°C.
10 cm long cuttings with 2 – 4 leaves taken from 2 month old branches can be used. These are placed in the nursery under 40 – 60% shade under fog. It takes about 12 weeks to get a rooted and fairly lignified seedling.
Layering can also be prepared by rooting them from the internodes. Results are best when foliage is at its densest, between August and October, with up to 50% success on 12 year old trees.

Customs and Traditions –
Triplochiton scleroxylon is a timber tree known by the common names of abachi or obeche (in Nigeria), wawa (in Ghana), ayous (in Cameroon) and sambawawa (in the Ivory Coast). The tree is the official state tree of Ekiti State in Nigeria.
This plant also has edible uses.
The cooked leaves are eaten and used as a cooked vegetable or dip in traditional West African cooking.
The plant is also used in traditional medicine to treat edema and as an anodyne.
Other uses include agroforestry.
The trees are often kept on cocoa plantations to serve as shade trees. In Nigeria Triplochiton scleroxylon is planted in agroforestry systems associated with cocoa.
The plant is a natural pioneer species, rapidly encroaching on open land especially in abandoned farmland. It could be used to help re-establish native forest or as a nurse tree in creating a woodland garden.
However, the main uses of this tree are those relating to timber and bark.
The bark is used to cover the roof and walls of the huts.
The heartwood is whitish to pale yellow in color; it is indistinctly delimited by the up to 15 cm wide band of slightly paler sapwood. The grain is generally intertwined, sometimes straight; moderately coarse texture. The wood has a ribbon-like appearance on the quarter-sawn faces and is lustrous. Fresh wood has an unpleasant odor which disappears when dried. The wood is very light; very soft; not durable, being subject to fungal attack, and susceptible to termites, beetles and wood borers; for this reason it should not be used in contact with the ground or exposed to bad weather. Cures quickly with little risk of control or distortion; when dry it is moderately stable to stable in service. Works easily with hand and machine tools; ordinary saw teeth and cutting tools can be used; sharp edges are needed for a smooth finish, and wood tends to tear in the mortise; a 15° cutting angle is recommended when planing to avoid lacerations; peeling and slicing properties are good; wood stains and polishes well; grouting is recommended to obtain a good finish; the nailing and screwing properties are rather poor; splitting may occur; gluing is no problem, although it must be done carefully as wood is absorbent. The carving characteristics are good.
The wood is used extensively for interior joinery, panelling, mouldings, furniture, boxes and crates, sculpture, matches, pencils, peeled and sliced veneer for interior and exterior plywood, fiberboard and chipboard, and battens. It is of great importance in the construction of houses, for beams, posts and planks, and is also used for roof tiles. The wood from the buttresses is used to make doors, trays, bowls and sandals, and the bowl is used for dugout canoes. Wood pulp can be used to make paper of modest quality.
Obeche wood has low shrinkage and hardness, with compressive strength of 31 Mpa, flexural strength of 74 Mpa and 6100 Mpa.
It should be noted that sawdust causes occupational allergic contact dermatitis, allergic rhinitis and asthma in sawmill workers.
This wood is also used by luthiers. Gibson and Fender Japan have used the wood to produce limited edition guitars.
English guitar maker Shergold used Obeche wood as the body on some of their limited edition models in the 1970s. It is also used for quality framing in oil paintings, drawings, watercolors and other similar works of art.
From an ecological point of view, it should be noted that this plant is home to the African silk moth, Anaphe venata, whose caterpillars feed on the leaves and spin the cocoons which are then used to make silk.
Unfortunately the wood is exploited in its natural habitat, in fact it is an unsustainable crop in some areas.
In some areas the plant’s range is extending due to its successful colonization of deforested and abandoned farmland. It is currently classified as “Least Concern” on the IUCN Red List of Threatened Species (2011).

Method of Preparation –
Triplochiton scleroxylon is an important tree in the economy of western tropical Africa and is utilized both for alimentary and medicinal purposes but, above all, for wood and other parts.
The leaves are eaten cooked, as a cooked vegetable or a sauce in traditional West African cooking.
In traditional medicine it is useful for treating edema and is also anodyne.
Other uses are agroforestry especially in areas where to rebuild tree covers or as a shading plant for cocoa.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Photo source:
– http://www.westafricanplants.senckenberg.de/images/pictures/triplochiton_scleroxylon__ms1778_2385_c92b47.jpg
– http://mediaphoto.mnhn.fr/media/1441390638460cXZdcgfx5kuXsOEj

Attention: The pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not in any way represent a medical prescription; we therefore decline all responsibility for their use for curative, aesthetic or food purposes.