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.
