Which plants to plant for Part A?

For a vascular plant --> A sunflower, because they are apparently easy to grow and the smaller types begin to flower before 3 months.

For a non-vascular plant --> A liverwort, because they are more well-known than hornworts and they are also apparently easy to grow.

However, I will further investigate these types of plants when I go to the local "Flower Power" today. :)