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Nomenclature etc. ZYGOPHYLLACEAE. G. officinale L., G. sanctum, G. coulteri A. Gray. Trade and local names: G. officinale: guajak (CZ, RU, HU); gaiac (FR); guaiacum wood (GB); pockhout (NL); gwajak (PL); guaiac (RO); guayacán (ES, VE); palo santo (CU, MX); Domingo- Jamaika- Panama Pockholz, Franzosenholz (DE); G. sanctum, G. coulteri: guayacan blanco, palo santo (cAm); Mexiko-Pockholz (DE); guayacancillo (MX). Listed in CITES Annex II (the entire genus).
Description based on 8 specimens. Tree. Geographic distribution: Mexico and Central America, Caribbean, tropical South America.
General. Heartwood basically brown, black, green; with streaks. Sapwood colour distinct from heartwood colour. Odour distinct (similar to rubber). Density 0.95–1.15–1.3 g/cm³. With greasy surface.
Vessels. Wood diffuse porous. Vessels exclusively solitary. Average tangential vessel diameter 15–68–80 µm. Average number of vessels/mm² 6–10–14. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 2–4 µm. Vessel-ray pits with distinct borders, similar to intervessel pits. Other deposits present (greenish-black, also in trasition zone from sapwood to heartwood).
Tracheids and fibres. Fibres very thick-walled. Average fibre length 440–590–830 µm. Fibre pits common in both radial and tangential walls, distinctly bordered.
Axial parenchyma. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse, or diffuse-in-aggregates. Paratracheal axial parenchyma scanty, or vasicentric (often incomplete), or unilateral. Axial parenchyma as strands. Average number of cells per strand: (1–)2–4.
Rays. Rays (12–)17–19 per tangential mm, exclusively uniseriate. Height of large rays up to 500 µm. Rays composed of a single cell type (homocellular); homocellular ray cells procumbent.
Storied structures. Storied structure present, all rays storied, axial parenchyma storied, vessel elements storied, fibres storied. Number of ray tiers per axial millimetre 8–10.
Secretory structures. Intercellular canals absent.
Mineral inclusions. Crystals not observed. Silica not observed.
Physical and chemical tests. Heartwood not fluorescent. Water extract not fluorescent; colour of water extract colourless to brown. Ethanol extract fluorescent (weakly violet). Colour of ethanol extract colourless to brown. Splinter burns to charcoal (under noticable blistering during combustion).
Illustrations. • Macroscopic images. Guaiacum officinale. transverse (ca. 10x). tangential (natural size). • Transverse section. Guaiacum sanctum. solitary vessels of different sizes (V), with very thick cell walls. «---V. «---V. «---V. • Tangential section. Guaiacum sanctum. uniseriate rays, storied structure, fusiform parenchyma. • Radial section. Guaiacum sanctum.
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’.
