Prosopis alba

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iAlgarrobo blanco

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Fabales
Family:	Fabaceae
Subfamily:	Mimosoideae
Genus:	Prosopis
Species:	P. alba

Binomial name

Prosopis alba
Griseb.

For other tree species with similar names, see Algarrobo.

Prosopis alba is a South American tree species that inhabits the center part of Argentina, the Gran Chaco ecoregion and part of the Argentine Mesopotamia. It is known as algarrobo blanco in Spanish, which means "white carob tree" (the Spanish settlers gave it that name because of its similarity to the European carob tree). Other common names come from Guaraní: ibopé or igopé.

Prosopis alba is a medium-sized tree, measuring between 5 and 15 m in height and 1 m in diameter, though such tall specimens occur very rarely at present. The trunk is short and the treetop is globulous, sometimes reaching 10 m in diameter. The bark is thin, brown-grayish in colour, with streaks, and it has tanning properties.

The tree is employed for ornamental and utilitary roadside planting and windbreaks. Its timber, which is rather dense (relative density = 0.76) and difficult to work, is used for doors and floors, for paving blocks, shoe lasts and wine casks (where it replaces the European oak). The wood responds well to drying and is therefore valuable for work that requires stable dimensions regardless of humidity. It is also durable for outdoor use.

The flowers are small, greenish-white or yellowish, and hermaphroditic. Pollination, mediated by wind and insects, is alogamous (crossed), since the female reproductive organs are turned active before the male ones.

The fruits are modified pods, 20 cm long, with brown seeds about 7 mm long, and they contain a sweet floury paste (patay), very high in calories, that can be used for fodder or turned into flour for human consumption. In the 1940s a mildly intoxicating beverage called aloja was made from it through fermentation; in turn it was sometimes distilled to produce ethanol. Between half and three quarters of the fruit's weight is sugar.

The tree can reportedly tolerate drought, salt and sand; in fact, it is extremely efficient with regards to water consumption, it produces the most fruits in years of drought and has been successfully introduced in arid terrains. However, it cannot stand even mild frost.

P. alba and other species of algarrobo of genus Prosopis, such as P. nigra (algarrobo negro) are often confused or not correctly distinguished in botanical literature; in part this is due to the ease of hybridization of the genus.

[edit] Sources

Prosopis alba in the Purdue University website (J. A. Duke, 1983, Handbook of Energy Crops)
Libro del Árbol: Especies Forestales Indígenes de la Argentina de Aplicación Industrial (edited by Celulosa Argentina S. A., Buenos Aires, October 1975)