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H. G. Richter and M. J. Dallwitz

Heliocarpus americanus L. (Amores secos)

Nomenclature etc. TILIACEAE. Syn.: Heliocarpus popayannensis Hook & Arn. Trade and local names: amores secos, apeyva, yvyra pire hu, tapika guasu (PY); amores secos (AR). Not protected under CITES regulations.

Description based on 5 specimens. Tree. Geographic distribution: tropical South America and southern Brazil.

General. Growth ring boundaries indistinct or absent. Heartwood basically white or grey and brown, without streaks. Sapwood colour similar to heartwood colour. Odour indistinct or absent. Density 0.29 g/cm³.

Vessels. Vessels present. Wood diffuse-porous. Vessels arranged in no specific pattern, in multiples, commonly short (2–3 vessels) radial rows. Vessel outline rounded. Two distinct vessel diameter classes absent. Perforation plates simple. Intervessel pits alternate, average diameter (vertical) 9–15 µm, large, not vestured. Vessel-ray pits with distinct borders and with reduced borders or apparently simple, similar to intervessel pits and different from intervessel pits, rounded or angular, 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 not observed.

Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres very thin-walled. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Helical thickenings absent. Fibres non-septate.

Axial parenchyma. Axial parenchyma present, not banded. Axial parenchyma apotracheal and paratracheal. Apotracheal axial parenchyma diffuse and diffuse-in-aggregates. Paratracheal axial parenchyma scanty. Axial parenchyma as strands. Average number of cells per axial parenchyma strand (2–)3–5(–7). Unlignified parenchyma present. Non lignified parenchyma in broad bands or larger flecks, irregularly distributed.

Rays. Rays present, multiseriate (also if only few), (1–)3–5(–6) cells wide, of medium width (3–5 seriate). Rays with multiseriate portions as wide as uniseriate portions absent. Aggregate rays absent. Rays of two distinct sizes. Height of large rays commonly over 1000 µm. Rays composed of two or more cell types (heterocellular). Heterocellular rays with square and upright cells restricted to marginal rows, mostly 1 marginal row of upright or square cells and mostly 2–4 marginal rows of upright or square cells. Sheath cells present. Tile cells absent. Perforated ray cells absent. Disjunctive ray parenchyma end walls indistinct or absent. With some longitudinally fused rays.

Storied structures. Storied structure present, some rays storied, some not, axial parenchyma storied, vessel elements storied, fibres storied. Arrangement of tiers irregular. Rays locally irregularly 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 upright and/or square and procumbent, upright and/or square ray cells chambered and not chambered. 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 and more than one. Crystals in one cell or chamber of the same size. Crystal containing cells of normal size. Cystoliths absent. With some subdivided (2–4, up to 8 times) square and upright marginal ray cells. Silica not observed.

Physical and chemical tests. Heartwood not fluorescent. Water extract not fluorescent; basically colourless to brown or shade of brown. Ethanol extract not fluorescent. Colour of ethanol extract colourless to brown or shade of brown. Chrome azurol-S test positive (only along the periphery of the reaction area, possibly as a consequence of fungal decay). Froth test positive. Splinter burns to full ash. Ash other than white, grey, yellow or brown (dark grey).

Illustrations. • Transverse section. Heliocarpus americanus. Specimen with (left) and without (right) amply developed unlignified parenchyma. • Tangential section. Heliocarpus americanus. • Radial section. Heliocarpus americanus. • Crystals. Heliocarpus americanus. Prismatic crystals in septate ray cells (left) and non-septate axial parenchyma cells (right).


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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