Originally these tropical dry forests stretched along the Pacific coast of Central America from southwest Mexico (southern Chiapes) through Guatemala, El Salvador, Honduras, and Nicaragua to northwestern Costa Rica, in a zone where there is a prolonged dry season, but today these forests are highly fragmented. In altitude they range from sea level to about 800 m and are usually low stature, semi-deciduous forests with no more than two vertical tree stories. Certain trees can, however, reach heights of up to 30 m. In southern sectors the common trees include Annona holosericea, Bursera simoruba, Casearia arguata, Eugenia salmensis, Guazuma ulmifolia, Jacquinia pungens, Tabebuia chrysantha and a variety of endemic and near endemic taxa such as Bombacopsis quinatum (Bombacaceae), Brosimum costaricensis (Moraceae), Dalbergia retusa (Fabaceae), Enterolobium cyclocarpum (Fabaceae) and Jacquinia macrocarpa (Theophrastaceae). Most of the trees belong to the Leguminosae superfamily of Fabaceae and many have associations with nitrogen fixing bacteria or have symbiotic relationships with various species of ant. The presence of Bombacopsis quinatum is of considerable biogeographical interest since it represents a family (Bombacaceae), which includes the baobabs of Africa and Australia. These are said to be descendents of Gondwanan ancestors and the presence of Bombacopsis quinatum in the Neotropics is quoted as evidence of continental drift. Bursera simoruba (naked indian) is of interest for its ability to photosynthesis through its shiny green bark. The under storey may include various shrubs such as the endemic Cupania guatemalensis (Sapindaceae), Machaerium biovulatum (Fabaceae) and Miconia argentea (Melastomataceae), clumps of palms (mainly species of Bactris) and occasional terrestrial bromeliads. Epiphytes are sparsely distributed and not conspicuous, but the crowns of trees are often lightly festooned with orchids, bromeliads, mosses, lichens, and there are occasional lianas.

References

Frankie, G. W., Baker, H. G. & Opler, P. A. 1974. Comparative phenological studies of trees in tropical wet and dry forests in the lowlands of Costa Rica. Journal of Ecology, 62: 881-919.

Gentry, A. H. 1995. Diversity and floristic composition of neotropical dry forest. In: Seasonally Dry Tropical Forests. Eds. S. H. Bullock, H. A. Mooney & E. Medina. Cambridge University Press.

González-Rivas, B., Tigabu, M., Gerhardt, K. Castero-Marin, G. & Odén. 2006. Species composition, diversity and local uses of tropical dry deciduous and gallery forests in Nicaragua. Biodiversity and Conservation, 15: 1509-1527.

Hartshorn, G. S. 1989. Tropical and subtropical vegetation of meso-America. In: North American Terrestrial Vegetation. Eds. M. G. Barbour and W. D. Billings. Cambridge University Press.

Janzen, D. H. 1983. Costa Rican Natural History. The University of Chicago Press.

Leopold, A. S. 1950. Vegetation zones of Mexico. Ecology, 31: 507-518.

Lieberman, D., Lieberman, M., Peralta, P. & Hartshorn, G. S. 1996. Tropical forest structure and composition on a large-scale altitudinal gradient in Costa Rica. Journal of Ecology, 84: 137-152.

Lot, E. J. & Atkinson, T. H. 2006. Mexican and Central American Seasonally Dry Tropical Forests: Chamela-Cuixmala, Jalisco, as a Focal Point for Comparison. In: Neotropical Savannas and Seasonally Dry Forests. Plant Diversity, Biogeography, and Conservation. Eds. R. T. Pennington, G. P. Lewis and J. A. Ratter. Taylor & Francis.

Murphy, P. G. & Lugo, A. E. 1995. Dry forests of Central America and the Caribbean. In: Seasonally Dry Tropical Forests. Eds. S. H. Bullock, H. A. Mooney and E. Medina. Cambridge University Press.

Ramamoorthy, T. P., Bye, R., Lot, A. & Fa, J. 1993. Biological Diversity in Mexico: Origins and Distribution. Oxford University Press.

Ricketts, T. h. et al. 1999. Terrestrial Ecosystems of North America - a conservation assessment. World Wildlife Fund, USA and Canada. Island Press, Washington.

Rico-Gray, V., Garcia-Franco, J. G., Puch, A. &  Sima, P. 1988. Composition and structure of a tropical dry forest in Yucatan, Mexico. International Journal of Ecology and Environmental Sciences, 14: 21-29.

Sabogal, C. 1992. Regeneration of tropical dry forests in Central America, with examples from Nicaragua. Journal of Vegetation Science, 3: 407-416.

Sabogal, C. & Valerio, L. 1998. Forest composition, structure, and regeneration in a dry forest of the Nicaraguan Pacific Coast. In: Forest biodiversity in North, Central and South America and the Caribbean. Eds. F. Dallmeier and J. A. Comiskey. Man and the Biosphere Series, Vol. 21. The Parthenon Publishing Group.

Sanchez-Sanchez, O. & Islebe, G. A. 2002. Tropical forest communities in southwestern Mexico. Plant Ecology, 158: 183-200.

Sawyer, J. O. & Lindsey, A. A. 1971. Vegetation of life zones in Costa Rica. Indiana Academy of Science, Monograph 2: 1-214.

Seymour, F. C. 1980. A checklist of the vascular plants of Nicaragua 1968-1976. Phytological Memoirs, 1: 1-314.

Taylor, B. W. 1963. An outline of the vegetation of Nicaragua. Journal of Ecology, 51: 27-54.

Trejo, I. & Dirzo, R. 2002. Floristic diversity of Mexican seasonally dry tropical forest. Biodiversity and Conservation, 11: 2063-2048.

Zuchowski, W. 2007. Tropical Plants of Costa Rica. A Zona Tropical Publication from Comstock Publishing Associates.