CLONAL GROWTH AND RAMET PERFORMANCE IN THE WOODLAND HERB, ASARUM CANADENSE

1 We report the results from a 7-year study on the patterns of reprodu ction and vegetative spread of Asarum canadense, conducted in replicat e plots located in the understorey of early and late successional fore st. 2 We recorded the spatial location, size, demographic performance and clonal fragment identity of all A. canadense ramets in our plots, as well as the position and fate of seedling recuits. We also collecte d detailed morphological data on patterns of clonal growth. 3 Recently germinated plants and the much larger, clonally produced daughter ram ets had equal survivorship. Size also had little impact on rhizome pro duction. Within sets of genetically identical ramets, flowering ramets were larger than non-flowering ramets. When there was an effect of ha bitat, ramets performed best in late successional forest. 4 Neither se xual nor asexual reproduction decreased the future performance of a ra met. Having connections to other ramets had little effect on survivors hip or rhizome production, but often was associated with an increased probability of flowering. Clones with more ramets outperformed smaller clones and spread the risk of genet mortality. 5 Rhizome lengths were shorter in the high light, early successional forest, but no other cl onal growth parameters differed between habitats. Empirically calibrat ed simulation and diffusion models indicated that the between-habitat differences in rhizome length were not great enough to affect the long -term expansion of clones. 6 Diffusion coefficients for the long-term spread by clonal growth or seed dispersal were compared for a number o f species. Diffusion model results indicated that plants can disperse as far by clonal growth as they do by seed, although the values for A, canadense were 14 and 8895 cm(2) year(-1), respectively. 7 Asarum can adense appears to be under unusually strong selection for seedling sur vival. As has been observed for some other clonal plant species, few c osts were found for either sexual or asexual reproduction.