Fraser trekked the Allegheny Mountains in 1789 when trans-Allegheny travel was limited to indigenous peoples' trails and one military trail, Braddock Road, built in 1751 and too far north of his journeys to be of help. He travelled with François André Michaux, and on the summit of the Great Roan was the first European to discover the Rhododendron catawbiense, now cultivated in many varieties. Of the rhododendrons he wrote We supplied ourselves with living plants, which were transmitted to England, all of which grew, and were sold for five guineas each.