Mama's plant symbolizes her anger. How is Mama's plant symbolic? It represents the importance of not giving up under tough circumstances. It reminds us that Mama is a good gardner.
Adjectives and Adverb phrases relate to prepositional phrases because if you remember what an adjective is, it describes a noun and then an adverb i believe can describe a verb, adjective, and other adverbs. Both adjective and adverb phrases contain prepositions, there fore relating them to prepositional phrases.... I hope this is what you were looking for and answered your question... :)
If you don't mind me asking, what are the following?