Abstract

Seed germination response of the Puerto Rican wet and dry forest populations of Tabebuia heterophylla treo::s was tested using a gradient of osmotic potentials from O to -1.5 MPa. Morphological comparisons were also made from adult specimens. Dry forest tress showed smaller leaves, fiuits, and seeds, and greater specific leaf weigjrt. Dry forest fiuits produced smaller seeds than wá forest fiuits when similar small fiuits were compared. Germination percentage was strongly reduced as osmotic potential decreased, and was significant in both seed origins. This reductioo was greater 00 seeds from the wá forest population. Days for germination showed the same response but this was less evident in the seeds from the dry foresto Osmotic potential lower than -0.9 MPa. compláely arrested seed germination in both populations. No sigJlificant difference in final germination percentage and days to germinate exist at higll osmotic potentials in both seed populations. This physiological capacity along with the morphological modifications indicates why this species can maintain viable populations in the contrasting environmental conditions ofthe dry and moist forest habitats.