Intrapopulational Variation in the Germination of Seeds in Hyptis Suaveolens

Seeds collected from the same population of Hyptis sauveolens Poit. show a great variability in size, which is correlated with differences in the germination response. For experimental purposes these seeds were grouped in three weight categories and subjected to continuous light or darkness at five temperatures (20 degrees to 40 degrees C). Substantial differences, both in total germination percentages and in rate of germination, were observed between the groups tested. The period necessary for light saturation depends on the conditions of previous incubation in darkness and on the weight class tested. Both in initial photosynthetic area and in dry weight, seedlings derived from the smallest seeds differ significantly from seedlings derived from the other groups. The possible ecological significance of the heterogeneity in the germination reponse and in the early performance of the plantlets, may have important ecological significance.