Included here is a small area of the Chaco or Gran Chaco in South America. Chacoan vegetation covers the vast plains of north-central Argentina, western Paraguay, southeast Bolivia and extends into Brazil along the a narrow strip parallel to the River Paraquay in Mato Grosso do Sul.

Chacoan Calcareous Palm Groves

Stands of the endemic, fan-leaved palm tree Copernicia alba (Arecaceae) are features of marshes in seasonally flooded, alkaline soils. It can reach heights of 8-10 m but stands are usually open with variable levels of density. Other arboreal species may include various endemic or near endemic species such as Acacia caven (Fabaceae), Geoffroea decorticans (Fabaceae), Sapium haematospermum (Euphorbiaceae) and Tabebuia nodosa (Bignoniaceae). The field layer is typically dominated by the endemic or near endemic grass Spartina argentinensis (Poaceae) although species of Paspalum may replace it in places. In seasonally flooded parts of northeastern Paraguay and southeastern Bolivia, Copernicia alba is often co dominant with the shrub or small tree Triplaris gardneriana (Polygonaceae) which is endemic to the upper basin of the Paraguay River. Other characteristic species include Albizia inundata and Parkinsonia aculeata. 

References

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Prado, D. E., Gibbs, P. E., Pott, A. & Pott, V. J. 1992. The Chaco-Pantanal transition in southern Mato Grosso, Brazil. In: Nature and Dynamics of Forest-Savanna Boundaries. Eds. P. A. Furley, J. Procter and J. A  Ratter.  Chapman & Hall.

Ragonese, A. E. & Castiglioni, J. C. 1970. La vegetacion del Parque Chaqueno. Boletin de la Sociedad Argentina de Botánica, 11: 133-160.

Spichiger, R. & Ramella, L. 1989. The forests of the Paraguayan Chaco. In: Tropical Forests - Botanical Dynamics, Speciation and Diversity. Eds. L. B. Holm-Nielsen, I. C. Nielsen and H. Balslev. Academic Press.

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