In the phrase "great, towering tree the ponderosa pine," a semicolon is not appropriate. If you want to separate two related independent clauses, a semicolon would be suitable. However, in this case, the sentence appears to be a fragment or a phrase rather than a complete thought.
If you meant to say something like "The great, towering tree is the ponderosa pine," you would not need a semicolon at all. If you intended to link two closely related independent clauses, you could use a semicolon like this: "The ponderosa pine is a great, towering tree; it stands tall in the forest."
Please clarify if you have a specific structure in mind!