PHENOLOGY AND FLOWERING PERIODICITY OF NEOTROPICAL DRY FOREST SPECIES- EVIDENCE FROM HERBARIUM COLLECTIONS

To examine the potential contribution of herbarium material to the des cription and analysis of tropical tree phenology, flowering times and geographical distribution were graphed for 1673 flowering collections from 18 species native to Neotropical dry forests and phenological dif ferences between species were analysed. These include the timing and d uration of flowering as well as morphological differences such as flow ering on leafless twigs vs flowering on shoots bearing old or new foli age. Species-specific flowering periods of herbarium collections are s imilar to those observed in phenological field studies, but are often longer because of the larger geographical and temporal sampling range. Conspecific collections of different geographical origin show distinc t differences in flowering periodicity, which are correlated with diff erences in the timing and intensity of the dry season. Interspecific d ifferences in the timing of phenology relative to the dry season indic ate differences in the control of phenology by seasonal drought. Herba ria thus represent a large potential source of phenological informatio n which can either supplement and extend phenological field studies or provide phenological information for dry forest species not studied i n the field but well represented in herbarium collections.