Final answer:
The protagonist of the story involving Mrs. Bertha Flowers is the unnamed narrator, Dorothy Wordsworth, who is a round and dynamic character, showing development through the story.
Step-by-step explanation:
The protagonist in the story with Mrs. Bertha Flowers is the unnamed narrator. When identifying the protagonist in a literary work, we look for the central character who drives the plot and is typically the one most developed through the narrative. In this case, the narrator, Dorothy Wordsworth, is the closest to a protagonist as she is the most developed character, who not only experiences a journey but is also changed by it. She is the person telling the story and, despite not being heavily described physically, we understand that she has a passion for botany. Her engagement with the environment, coupled with personal growth throughout the story, suggests she fulfills the role of the protagonist more than any other character, including Mrs. Bertha Flowers.