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H. G. Richter and M. J. Dallwitz

Guazuma ulmifolia Lamk. (Guácimo)

Nomenclature etc. STERCULIACEAE. Syn.: Guazuma tomentosa H.B.K., Guazuma polybotrya Cav., Theobroma guazuma L., Guazuma bubroma Tuss., Theobroma foliis serratis L., Diuroglossum rufescens Turcz. Trade and local names: kamba akã (PY); imbiruçú, embirú, mutamba (BR); guácima, guácimo, cuaulote, aquiché, kabal-pixoy, pixoy, acashti, ajillá, majagua de toro, nocuana-yana, palote negro, parandesicua, tablote, tzuni, tzyui, uiguie, ya-ana, yaco granadillo, yaco de venado, zam-mi, áquich, ajya, k'olin kakaw (MX); guácimo, g. blanco (VE); guásimo (PE); guásima (CU). Not protected under CITES regulations.

Description based on 2 specimens. Tree. Geographic distribution: Mexico and Central America, Caribbean, tropical South America, and southern Brazil.

General. Growth ring boundaries distinct. Growth ring limits demarcated by a nearly invisible (uniseriate) marginal parenchyma band, local thickening of rays, and thicker walled latewood fibres. Heartwood basically white or grey. Sapwood colour similar to heartwood colour. Density 0.48–0.65 g/cm³.

Vessels. Vessels present. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows and radial rows of 4 or more. Vessel outline rounded. Two distinct vessel diameter classes absent. Average tangential vessel diameter (60–)110–150(–170) µm; diameter of vessel lumina: medium and large. Average number of vessels/mm² 6–19; vessels per square millimetre few. Average vessel element length 330–400 µm. Average vessel element length medium. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 4–5 µm, small, not vestured. Vessel-ray pits with distinct borders, similar to intervessel pits, of uniform size or type, of the same type in adjacent elements, located throughout the ray. Helical thickenings absent. Tyloses in vessels absent. Other deposits in heartwood vessels present, brown organic contents, rather scarce.

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres of medium wall thickness. Average fibre length 850–1940 µm. Average fibre length medium. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate.

Axial parenchyma. Axial parenchyma present, banded. Axial parenchyma bands marginal (or seemingly marginal) (marginal bands hardly visible in transverse section due to the similarity (dimension and wall thickness) with fibres), fine, up to three cells wide. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates. Paratracheal axial parenchyma scanty and vasicentric. Axial parenchyma as strands. Average number of cells per axial parenchyma strand 3–8. Unlignified parenchyma absent. The number of cells per strand differs for paratracheal (4–8) and apotracheal (3–5) axial parenchyma.

Rays. Rays present, 5–13 per tangential mm, multiseriate (also if only few), (1–)2–5 cells wide, narrow (2–3 seriate) and of medium width (3–5 seriate). Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of one size. Height of large rays commonly over 1000 µm. Rays composed of two or more cell types (heterocellular). Sheath cells absent. Tile cells present. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent. Rays considered heterocellular as procumbent and tile cells are mixed.

Storied structures. Storied structure present, some rays storied, some not, axial parenchyma storied, vessel elements storied, fibres storied. Arrangement of tiers regular (horizontal or straight) and irregular. Number of ray tiers per axial millimetre 2. Only the low (small) rays are storied.

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 ray cells and axial parenchyma cells. Crystal-containing ray cells procumbent. Crystals in procumbent ray cells not in radial alignment. Crystal-containing axial parenchyma cells chambered and not chambered. Number of crystals per cell or chamber one. Crystal containing cells of normal size. Cystoliths absent. Silica not observed.

Physical and chemical tests. Heartwood not fluorescent. Water extract not fluorescent; basically colourless to brown or shade of brown to yellow or shade of yellow. Ethanol extract not fluorescent. Colour of ethanol extract colourless to brown or shade of brown.

Illustrations. • Transverse section. Guazuma ulmifolia. • Tangential section. Guazuma ulmifolia. • Radial section. Guazuma ulmifolia -- note tile cells (blow-up lower left corner).


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: 25th June 2009. http://delta-intkey.com’.

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