| | Commercial timbers |
Nomenclature etc. FABACEAE-CAESALPINIOIDEAE. Trade and local names: m'kusi, i'gusi, i'kusi, umgusi (ZW); m'papa (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), southern Africa.
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 in short (2–3 vessels) radial rows or in radial rows of 4 or more. 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, pits vestured. Vessel-ray pits with distinct borders, similar to intervessel pits. Other deposits present (yellowish brown).
Tracheids and fibres. Fibres of medium wall thickness. Average fibre length 630–1450 µm. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres non-septate.
Axial parenchyma. Axial parenchyma banded. Bands marginal (or seemingly marginal). Bands fine. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma scanty, or vasicentric, or confluent, or unilateral. Axial parenchyma as strands. Average number of cells per strand: 2–4.
Rays. Rays 7–11 per tangential mm, multiseriate, 2–3(–4) cells wide. Height of large rays up to 500 µm. 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.
Storied structures. Storied structure present, all rays storied, axial parenchyma storied, vessel elements storied, fibres storied. Arrangement of tiers regular, or irregular. Number of ray tiers per axial millimetre 3–4.
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). Silica not observed.
Physical and chemical tests. Heartwood not fluorescent. Water extract not fluorescent; colour of water extract red. Ethanol extract fluorescent (green). Colour of ethanol extract red. Froth test positive.
Illustrations. • Macroscopic images. transverse (ca. 10x). radial (natural size). • Transverse section. variable expression of cross section in different specimens as a function of vessel size/frequency and amount of axial parenchyma. • Tangential section. • Radial section.
The interactive key allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, summaries of attributes within groups of taxa, and geographical distribution.
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: 9th April 2019. delta-intkey.com’.
