XVI International Botanical Congess

Seed biology of 7 Rhus species (aromatica, copallina, glabra, microphylla, trilobata, typhina, and virens) was compared, with particular attention to R. aromatica and R. glabra. Flowering/fruiting phenology of R. aromatica and R. glabra was separated by ca. 2 mo, but timetable and pattern of fruit/seed development were similar. Fruits of R. aromatica ripened in June and were dispersed rapidly, those of R. glabra matured in August, but dispersal was delayed until winter. Seeds of all species were physically dormant due to a water-impermeable endocarp that was made permeable by H2O-boiling in R. glabra and R. typhina and by H2SO4-soaking in R. aromatica, R. trilobata, and R. virens. Embryo dormancy was present only in R. aromatica. Soil seed bank of R. glabra was larger and persisted longer than that of R. aromatica.