Natural History of Guacimo Fruits (Sterculiaceae: Guazuma ulmifolia) with Respect to Consumption by Large Mammals

Abstract

Guazuma ulmifolia (Sterculiaceae) is a shrubby tree common in the Central American lowlands in deciduous forest, and in the pastures cut out of it. The tree flowers in April-May (end of dry season) and bears dormant, incompletely expanded fruit until the end of the rainy season (November-December), at which time the fruits rapidly expand and ripen to fall during the first half of the dry season. The fruits are avidly eaten by livestock. A horse may consume 300-2,100 fruits in a meal, does not distinguish between fresh fruits that have been attacked by bruchid beetles and intact fruits, and defecates large numbers of viable seeds 2-5 days later. Moistened seeds germinate readily in horse dung or in soil. There are hard letter-shaped structures in the mesocarp of the fruit wall and a very hard core, both of which are large enough to function in preventing complete occlusion ofthe molar mill, an act which would crush the soft small seeds. Guazuma ulmifolia (guacimo) is probably one of the trees whose fruits would have been eaten and the seeds dispersed by the Pleistocene herbivorous megafauna that once roamed Central America.