Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Field and laboratory studies of aspects of the dispersal ecology of Solanum dulcamara, a perennial species bearing fleshy fruits, were conducted near London, Ontario. Although there were annual and inter-habitat variations, 51.9% of the dispersant fruits were not ripe. Each fruit type contained some viable seeds, but germination and seedling emergence were more rapid from ripe fruits. Seeds from which the flesh had been removed produced seedlings at a faster rate than seeds sown within intact fruits. Seeds sown within intact fruits were more likely to produce seedlings in later years. In one such study the bulk of seedlings emerged in the second rather than first year. Annual differences in the number of fruits, the probability of dispersal, and the retention period of dispersant fruits at various stages of development were observed in the field habitats. More fruits were set per inflorescence early in the season, but later fruits had more flesh and higher flesh-to-seed dry weight ratios when ripe. There were no seasonal differences in the retention period of dispersant fruits. Seeds from early fruits germinated more slowly than those from later fruits. Differences in the attributes of ripe fruits were mostly the results of adjustments to the flesh rather than the seeds, and inter-habitat differences may have been the result of phenotypic plasticity. The highest percentage of unripe fruits dispersed in the seasonally flooded and heavily shaded swamp habitat. The number of buds per inflorescence, the number of inflorescences per stem, the probability of fruit-set, and the probability of dispersal were generally low at the swamp, however. Fruits ripened most rapidly at the more open riverbank, where the number of buds per inflorescence, the number of inflorescences per stem, the percentage fruit-set and the probability of dispersal were high. Comparable patterns at the seasonally flooded marsh habitat and field-edge environment of the field station habitat were intermediate. However values at the marsh tended to parallel those at the swamp, and the values at the field station approached those at the riverbank.



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