Final answer:
Directional selection can lead to larger flower size over time, but there is often a trade-off between flower size and number.
Step-by-step explanation:
Directional selection is a process in which natural selection favors individuals with a trait at one extreme of a population's variation, leading to a shift in the average value of the trait over time. In the case of larger flowers, directional selection would result in an increase in average flower size over successive generations. This could be driven by factors such as pollinators preferring larger flowers or larger flowers being better adapted to compete for resources.
However, there is often a trade-off between flower size and number. This means that as flower size increases, the number of flowers produced may decrease. For example, larger flowers may require more resources to produce, diverting resources away from reproduction. On the other hand, smaller flowers may be able to produce more flowers with limited resources. The specific trade-off between flower size and number would depend on the ecological context and selective pressures acting on the population.