Is either tulip or daffodil an appositive phrase in this one bulb, either tulip or daffodil, in each hole.

Appositive phrases are used to further describe the nouns before them. They act like adjectives, although they aren't necessarily always adjectives. In most cases, they are separated from the rest of the sentence using commas on both sides. So yes, you are right - the appositive phrase in this sentence is either tulip or daffodil.

Go to school and learn fool