Jacquinia pungens, a Heliophile from the Understory of Tropical Deciduous Forest

Abstract

The general ecology of the understory shrub Jacquinia pungenis is described, with special reference to its behavior of bearing leaves during the dry season (when the overhead forest canopy is deciduous) and being deciduous during the rainy season. The bush is restricted to those stages of lowland deciduous forest succession ranging from 10 to 50 years of age; it appears to starve to death or be competitively excluded from habitats where it is continuously insolated, and from older or wetter forest where it does not receive enough sunlight owing to light obstruction by the deep canopy during the dry season. As expected for a plant that is vegetatively active during the dry season, the plant is especially well protected from herbivores by needle-tipped leaves and toxic compounds in the foliage. Effectively, J. pungens has invaded a seasonally available prairie and has the bush life form characteristic of woody plants in such well-insolated habitats. ALMOST ALL NON-RIPARIAN woody plants in Central American deciduous tropical forest bear leaves during the rainy season and are leafless or vegetatively dormant during the major dry season (January-April). An obvious way for a plant to avoid the intense interspecific vegetative competition of such a forest habitat is to bear leaves during the dry season and to be deciduous during the rainy season. A shrub, Jacqiinita pungens A. Gray (Theophrastaceae), does this and is thus important in illustrating how the number of species in a habitat can be increased through the invasion by a species that uses resources unused by other members of the