Hi, Richard. You are right: "le" refers to "el rosal". However, this is a particular use of the pronoun. We call it "dativo de interés". Rather than replacing "el rosal", this "le" reinforces it. It may even look redundant but that's its function. Without it, the sentence would still make sense, but for a Spanish speaker it would lack something: "salieron capullos al rosal". Another example would be "Me dejé las llaves en la casa" (I left my keys in the house.) "Me" is reinforcing that it was me who left the keys (and that they were my keys). One more example: "Le ensuciaste la alfombra" (You got his/her carpet dirty.) Again, "le" is merely emphasizing the fact that it was you who got the carpet dirty. I hope this clarifies your question. Gerardo.

You are completely right. "le salieron capullos al rosal" Indirect complement pronoun that replaces the rose