Abstract

The germination requirements, dormancy cycle and longevity of nine Rumex species were studied in field conditions and laboratory experiments to show the adaptations of the related species to their specific habitat. Within one genus, rather striking differences were observed in germination ecology. However, the closely related species, R. acetosa and R. scutatus, are very similar: they fruit in early summer; their seeds can germinate immediately after dispersal, and they are nondormant and short-lived. R. acetosella also has fruits in summer, but the seeds do not germinate the first season after dispersal. They are long-lived, but buried seeds do not show a dormancy cycle; they might germinate in different seasons after exposure to light. Seeds of four species (R. conglomeratus, R. maritimus, R. sanguineus and R. crispus) are long-lived and undergo a seasonal dormancy cycle, with a low level of dormancy in winter and early spring and a deep dormancy in summer as was already known for R. obtusifolius. These seeds are shed in the autumn, and they germinate mainly in the spring in consecutive years. R. maritimus also germinates in summer and autumn on drying muddy soils. The seeds of R. hydrolapathum only germinate on waterlogged soils, which explains its growth at the edge of streams and ponds. Its seeds are rather short-lived. The seeds of the species on very wet places require a higher temperature for germination.

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