Prota 7(2): Timbers/Bois d’œuvre 2
Bot. Jahrb. Syst. 43: 308 (1909).
Celtidaceae (APG: Cannabaceae)
African ita, ita (En).
Origin and geographic distribution
Celtis adolfi-fridericii is widespread, occurring from Côte d’Ivoire east to western Uganda and south to Gabon and DR Congo.
The wood, traded together with other Celtis spp. as ‘African celtis’, is used for light construction, flooring, joinery, interior trim, frames, staircases, furniture, ladders, sporting goods, agricultural implements, handles, pestles, crates, boxes, match splints, hardboard and particle board. It is suitable for mine props, ship building, railway sleepers, veneer and plywood. It is also used as firewood.
In traditional medicine, bark decoctions are taken to treat general malaise, severe cough, fever and headache, and as an emetic. A leaf decoction is used for treating sore eyes. In DR Congo bark pulp is applied on scarifications in the chest to relieve costal and side pains, and fruits have been used to treat tuberculosis. The bark is used as emetic and in magical preparations. The seeds are edible, and edible caterpillars are collected from the leaves and edible beetle larvae from dead trunks.
Production and international trade
The wood of Celtis adolfi-fridericii is mainly used locally and only occasionally traded on the international market in mixtures with other Celtis spp. Trade statistics are not available.
The heartwood is white to pale yellow when freshly cut, later turning to grey-white; it is not distinctly demarcated from the sapwood. The grain is usually straight, sometimes interlocked, texture moderately fine. The wood is usually lustrous.
The wood is medium-weight, with a density of about 700 kg/m³ at 12% moisture content, and fairly hard. Kiln drying requires care to avoid splitting and distortion. The rates of shrinkage are moderate, from green to oven dry 4.8% radial and 7.8% tangential.
At 12% moisture content, the modulus of rupture is 150 N/mm², modulus of elasticity 11,760 N/mm², compression parallel to grain 65 N/mm², shear 8 N/mm², cleavage 21 N/mm and Chalais-Meudon side hardness 7.2.
The wood works well with both hand and machine tools and has moderate blunting effect on cutting tools. Straight-grained stock planes well, but a cutting angle of 15° is recommended to avoid tearing in wood with interlocked grain. The wood finishes and polishes very well. It is difficult to nail and screw; pre-boring is recommended to prevent splitting. The wood glues well. The veneering properties are variable. The wood has a low durability with an expected service life of 1–8 years for external usage. It is susceptible to attacks of blue-stain fungi and insects, including termites and Lyctus borers. The heartwood is moderately resistant to preservative treatment, but the sapwood is permeable. Wood dust may cause allergic reactions and skin irritation in wood workers.
Some traces of alkaloids have been reported in the bark and leaves of Celtis adolfi-fridericii.
Semi-deciduous, medium-sized to fairly large tree up to 35(–50) m tall; bole branchless for up to 20(–30) m, usually straight and cylindrical, up to 100 cm in diameter, usually with wide-spreading buttresses up to 2(–5) m high; bark surface rough, brownish grey to dark grey, usually marked with horizontal ridges near the base of the bole, inner bark thick, granular, creamy with dark brown blotches; crown rounded, dark green, with branches drooping towards tips; twigs whitish short-hairy, soon becoming glabrous. Leaves alternate, simple and entire; stipules lanceolate, 3–6 mm long, hairy, caducous; petiole 0.5–2 cm long, grooved above; blade elliptical to ovate or obovate, 8–16(–20) cm × 5–10 cm, cuneate to rounded and very asymmetrical at base, with short-acuminate apex, leathery, glabrous except for some tufts of hairs in axils of veins below, slightly rough on lower surface, prominently 3-veined from the base and additionally with 1–3 pairs of lateral veins. Inflorescence an axillary cyme 1–5 cm long, short-hairy, many-flowered. Flowers unisexual or bisexual, regular, usually 5-merous, small, white to greenish, sessile; tepals 1–1.5 mm long, hairy; stamens free, incurved in bud and later spreading; ovary superior, ovoid, densely hairy, 1-celled, styles 2, 2-lobed; male flowers numerous and densely clustered, with rudimentary ovary; female flowers and/or bisexual flowers at tops of upper inflorescences, female flowers with rudimentary stamens. Fruit an ovoid to globose drupe 1.5–2 cm long, reddish when ripe, glabrous, crowned at top by remains of styles; stone globose, 1–1.5 cm long, pitted, whitish, 1-seeded. Seedling with epigeal germination; hypocotyl c. 5 cm long, epicotyl 3–4 cm long; cotyledons c. 1.5 cm long, thick and fleshy, notched at apex; first two leaves opposite, toothed.
Other botanical information
Celtis comprises about 100 species and is widespread in all tropical, subtropical and temperate regions. For tropical Africa 11 species have been recorded, 2 of which are endemic to Madagascar. Celtis is taxonomically a difficult genus, showing much morphological variability. Traditionally, it has been treated as part of the family Ulmaceae, but later it was often considered to belong to a separate family Celtidaceae, whereas from most recent research it was proposed to take up the latter family into Cannabaceae.
Wood-anatomical description (IAWA hardwood codes):
Growth rings: 1: growth ring boundaries distinct; 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; (7: vessels in diagonal and/or radial pattern); 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 26: intervessel pits medium ( 7–10 μm); (27: intervessel pits large (≥ 10 μm)); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 42: mean tangential diameter of vessel lumina 100–200 μm; (46: ≤ 5 vessels per square millimetre); 47: 5–20 vessels per square millimetre. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 79: axial parenchyma vasicentric; 80: axial parenchyma aliform; (81: axial parenchyma lozenge-aliform); 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand; (94: over eight cells per parenchyma strand). Rays: 98: larger rays commonly 4- to 10-seriate; 106: body ray cells procumbent with one row of upright and/or square marginal cells; 107: body ray cells procumbent with mostly 2–4 rows of upright and/or square marginal cells; (110: sheath cells present); 115: 4–12 rays per mm. Mineral inclusions: 136: prismatic crystals present; 137: prismatic crystals in upright and/or square ray cells; (138: prismatic crystals in procumbent ray cells); 141: prismatic crystals in non-chambered axial parenchyma cells; 144: druses present; 145: druses in ray parenchyma cells; (156: crystals in enlarged cells).
(E.K. Achi, A.A. Oteng-Amoako & P. Baas)
Growth and development
Celtis adolfi-fridericii is a non-pioneer light demander. Seedlings attain a maximum height of 40 cm after 1 year, and subsequently grow 20–100 cm per year. The tree is partly deciduous and the crown is never completely leafless. In West Africa flowering trees have been recorded from May to June and November to December. Fruits ripen about 4 months later. The fruits are relished by animals such as birds, monkeys, chimpanzees and gorillas, which probably disperse the seeds.
Celtis adolfi-fridericii is most common in semi-deciduous forest; it markedly prefers drier forests. It is often found in secondary forest and gallery forest, and occurs up to 900 m altitude. It prefers well-drained fertile soils.
Propagation and planting
The weight of 1000 seeds is about 65 g. Seeds germinate after 15–30 days with a quite low germination rate. Under natural conditions, seedlings are usually found in small to medium-sized forest gaps. Although they are more light-demanding than other Celtis spp., some shade is required for young seedlings; for older seedlings exposure to more light is necessary for optimal growth. Seedlings can be quite abundant in forest that has been subject to logging, but they are less common in burnt forest.
In the nursery, germination of seeds is rather erratic and usually takes about 1 month. Pre-treatment by soaking seeds in water and exposing them to the sun can accelerate germination and increase the germination rate.
In Ghana the minimum bole diameter allowed for harvesting Celtis adolfi-fridericii is 70 cm, in Cameroon 50 cm.
Handling after harvest
After felling, logs should be extracted from the forest as soon as possible or treated rapidly with preservatives because they are susceptible to attacks by blue-stain fungi and insects.
Celtis adolfi-fridericii is locally common and occurs often in secondary forest. It is unlikely to suffer from genetic erosion.
Celtis adolfi-fridericii has potential to serve as substitute for other Celtis species that are more commonly traded on the international timber market, such as Celtis mildbraedii Engl. and Celtis zenkeri Engl. Very little research has so far been done on Celtis adolfi-fridericii and research on its growth rates, propagation methods and management requirements is therefore warranted.
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Correct citation of this article:
Jiofack Tafokou, R.B., 2010. Celtis adolfi-fridericii Engl. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). Prota 7(2): Timbers/Bois d’œuvre 2. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, part of flowering twig; 2, part of inflorescence with many male flowers and one female flower; 3, leaf and fruit.
Redrawn and adapted by Achmad Satiri Nurhaman
obtained from W.D. Hawthorne
wood in transverse section
wood in tangential section