Nomenclature etc. FABACEAE-MIMOSOIDEAE. Syn.: Prosopis algarrobilla Griseb. var. nigra Griseb. Trade and local names: algarrobo dulce, a. morado, a. negro (AR); a. amarillo (UY). Not protected under CITES regulations.
Description based on 2 specimens. Tree. Geographic distribution: temperate South America.
General. Growth ring boundaries distinct or indistinct or absent. Growth ring limits, if distinct, demarcated by discontinuous marginal parenchyma bands composed of smaller and mostly crystalliferous cells; macroscopically, growth ring limits are quite distinct. Heartwood basically light to dark brown, with streaks. Sapwood colour distinct from heartwood colour. Odour indistinct or absent.
Vessels. Vessels present. Wood semi-ring-porous and 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) 5–7 µm, small, 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, abundant amber coloured deposits in vessels.
Tracheids and fibres. Vascular or vasicentric tracheids sporadic to absent. Fibres of medium wall thickness to very thick-walled. Fibre pits mainly restricted to radial walls, simple to minutely bordered. Fibres non-septate.
Axial parenchyma. Axial parenchyma present, banded. Axial parenchyma bands marginal (or seemingly marginal), bands much wider than rays, coarse, more than three cells wide. Axial parenchyma apotracheal, or paratracheal. Apotracheal axial parenchyma diffuse-in-aggregates ((or in longer bands)). Paratracheal axial parenchyma vasicentric, aliform, and confluent. Aliform parenchyma lozenge. Axial parenchyma fusiform and as strands. Average number of cells per axial parenchyma strand 2–4. Unlignified parenchyma absent.
Rays. Rays present, multiseriate (also if only few), 2–5 cells wide, 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 500 to 1000 µm. Rays composed of a single cell type (homocellular) and 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. Heterocellular rays only sporadically.
Storied structures. Storied structure absent.
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 not chambered. Crystals in procumbent ray cells not in radial alignment. Crystal-containing axial parenchyma cells chambered. Number of crystals per cell or chamber one. Crystal containing cells of normal size. Cystoliths absent. Compound crystals (twins) in procumbent and square ray cells; size of crystals and crystalliferous cells very variable. Silica not observed.
Illustrations. • Transverse section. Prosopis nigra. • Tangential section. Prosopis nigra. • Radial section. Prosopis nigra.
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’.