USDA Forest Service
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53705-2398
(608) 231-9200

 

Wood Technical Fact Sheet

 

 Piptadeniastrum africanum

syn. Piptadenia africana

Dahoma

Family: Leguminosae

Other Common Names: Mbeli (Liberia), Dabema (Ivory Coast), Dahoma (Ghana), Agboin, Ekhimi (Nigeria), Atui (Cameroon), Bokungu (Zaire), Mpewere (Uganda).

Distribution: Tropical West Africa from Senegal to Angola and across the Congo region to Uganda. Found in mixed deciduous and evergreen forests, often stands as a single tree on farmland.

The Tree: Reaches a height of 150 ft; boles straight, cylindrical, clear to 50 ft, buttresses sharp and widespreading to 15 ft. Coppices well.

The Wood:

General Characteristics: Heartwood light to golden brown; sapwood 2-in. wide, grayish to pale straw, distinct. Texture coarse; grain broadly interlocked producing an attractive ribbon figure; moderate luster; unpleasant odor when freshly cut and may return if timber is rewetted; sawdust may irritate skin and mucous membranes; may stain if in contact with iron under moist conditions.

Weight: Basic specific gravity (overdry weight/green volume) 0.56; air-dry density 43 pcf.

Mechanical Properties: (2-cm standard)

Moisture content Bending strength Modulus of elasticity Maximum crushing strength

(%) (Psi) (1,000 psi) (Psi)

Green(9) 1,000 1,430 5,320

12% 15,800 1,620 8,520

12% (27) 16,000 1,790 8,250

Janka side hardness 1,320 lb for green and 1,540 lb for dry material. Amsler toughness 266 in.-lb at 12% moisture content (2-cm specimen).

Drying and Shrinkage: Dries slowly, air-drying prior to kiln-drying is suggested; some material prone to collapse and warp, collapse not removable by reconditioning. Kiln schedule T2-D4 is suggested for 4/4 stock and T2-D3 for 8/4. Shrinkage green to ovendry: radial 3.9%; tangential 8.7%; volumetric 12.5%. Movement in service is rated as medium.

Working Properties: Works well, blunting of tooth edges most pronounced in sawing, cutting angle of 15 degrees is suggested for planing knives to minimize tearing of interlocked grain, nailing and gluing satisfactory, moderate wood- bending characteristics.

Durability: Heartwood is rated as durable, reported to be resistant to termite attack in West Africa but only moderately so in South Africa.

Preservation: Heartwood is rated as resistant to preservative treatments; sapwood moderately resistant.

Uses: Heavy construction, wharf decking, flooring.

Additional Reading: (3), (9), (27)