Influence of Germination Date on Survival and Seed Production in a Natural Population of Leavenworthia stylosa

The influence of germination date in 1970 on survival and seed production was studied in a population of the winter annual Leavenworthia stylosa in the field. The lowest percentage of survival was in plants from July-germinating seeds, while the highest percentage was in plants from seeds that germinated in midto late September and early October. Plants from July-germinating seeds produced more fruits and seeds per plant than plants from seeds that germinated in September or October. However, since a much higher percentage of plants from seeds that germinated in September and October survived, the number of seeds produced per 100 seeds germinated was highest in these plants. The fewest seeds produced per 100 seeds germinated were in plants from seeds that germinated after 4 October.