"Orange pekoe" is not a flavoring or additional ingredient. It refers to a grade of black tea, based on the size of the leaves.
It was a better name than "dust off the floor".
Orange Pekoe is actually considered a fairly average tea on the grading scale, but has become a generic name for any black tea in North America. A lot of what is in tea bags here is actually classed as "dust" grade, which is the lowest grade of tea. It literally is the dust that's left over. "Loose leaf" like Yorkshire Gold is usually fannings, which are small pieces left over from higher grades.
These grades are cheaper and usually produce a stronger brew. Not the best tea but there's nothing wrong with it either. They still make a good cup. Unless it's the really cheap crap like Lipton sells.
What Teavana sells is usually broken grade. Large pieces but not the whole leaf. True whole leaf grades are usually quite expensive.
https://en.wikipedia.org/wiki/Tea_leaf_grading