The type of punctuation used in literature has a strong bearing on how we read words and phrases. In this case, the semicolon here indicates a close relationship between two independent clauses. This allows us to understand that the speaker considers there to be a very close association between herself and the blossoming lime tree—as the speaker weeps, the tree also weeps by dropping flowers. That the tree is in blossom also serves to suggest that the speaker views herself as also in full bloom, or in the prime of her life, ready for love.