Commercial Timbers

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H. G. Richter and M. J. Dallwitz

Baikiaea plurijuga Harms (Mukusi)

Nomenclature etc. FABACEAE-CAESALPINIOIDEAE. Trade and local names: Mukusi, mKusi, iGusi, iKusi (ZW); mPapa (AO); Zambesi redwood, Rhodesian teak, Rhodesian redwood (GB, trade). Not protected under CITES regulations.

Tree. Geographic distribution: tropical Africa (Zimbabwe, Sambia, S.Angola, N.Namibia).

General. Growth ring boundaries distinct. Heartwood basically copper or orange brown, with streaks. Sapwood colour distinct from heartwood colour. Odour indistinct or absent. Density 0.58–0.78 g/cm³.

Vessels. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows or radial rows of 4 or more. Two distinct vessel diameter classes absent. Average tangential vessel diameter 40–70–90 µm. Average number of vessels/mm² 17–30. Average vessel element length 250–320–400 µm. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 5–8 µm, vestured. Vessel-ray pits with distinct borders, similar to intervessel pits. Helical thickenings absent. Tyloses in vessels absent. Other deposits in heartwood vessels present (yellowish brown).

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres of medium wall thickness. Average fibre length 630–1450 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate.

Axial parenchyma. Axial parenchyma banded. Axial parenchyma bands marginal (or seemingly marginal), fine, up to three cells wide. Axial parenchyma paratracheal. Paratracheal axial parenchyma scanty, vasicentric, confluent, and unilateral. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 2–4.

Rays. Rays 7–11 per tangential mm, multiseriate (also if only few), 2–3(–4) cells wide. Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of one size. Rays composed of a single cell type (homocellular), or two or more cell types (heterocellular); homocellular ray cells procumbent. Heterocellular rays with square and upright cells restricted to marginal rows, mostly 1 marginal row of upright or square cells. Sheath cells absent. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent.

Storied structures. Storied structure present, all rays storied, axial parenchyma storied, vessel elements storied, fibres storied. Arrangement of tiers regular (horizontal or straight), or irregular. Number of ray tiers per axial millimetre 3–4.

Secretory structures. Oil and mucilage cells absent. Intercellular canals absent. Laticifers or tanniniferous tubes absent.

Cambial variants. Included phloem absent. Other cambial variants absent.

Mineral inclusions. Crystals present, prismatic, located in axial parenchyma cells. Crystal-containing axial parenchyma cells chambered. Number of crystals per cell or chamber one. Crystal containing cells of normal size and enlarged (idioblasts). Cystoliths absent. Silica not observed.

Physical and chemical tests. Heartwood not fluorescent. Water extract not fluorescent; basically red or shade of red. Ethanol extract fluorescent (green). Colour of ethanol extract red or shade of red. Froth test positive.

Illustrations. • Macro images. Baikiaea plurijuga. • Transverse section. Baikiaea plurijuga. Note: Variable expression of x-section in different specimens as a function of vessel size/frequency and amount of axial parenchyma. • Tangential section. Baikiaea plurijuga. • Radial section. Baikiaea plurijuga.


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Cite this publication as: ‘Richter, H.G., and Dallwitz, M.J. 2000 onwards. Commercial timbers: descriptions, illustrations, identification, and information retrieval. In English, French, German, Portuguese, and Spanish. Version: 25th June 2009. http://delta-intkey.com’.

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