The theme of transformation pops up in two major ways in the story of "Apollo and Daphne." We'll go with the glaringly obvious one first: at the end of the story, Daphne's father transforms the young nymph into a laurel tree. Why a tree? Hmmm, well we guess it's better than a rock or something. At least Daphne will have a long life in her new tree form, and, thanks to Apollo's blessing, her laurel leaves will always be green (and will be really good in chicken soup).
The other kinds of transformations that we see in the story center around matters of the heart. Thanks to Cupid's gold-tipped arrow, Apollo falls head over heels for the young nymph. Daphne, on the other hand, is transformed into someone who despises the very idea of love when Cupid shoots her with his lead-tipped arrow. The story shows us how feelings of love and disgust can lead to dangerous transformations.