They are known botanically as Halesia hispida and H. corymbosa, but ever since their introduction they have been known as Pterostyrax in gardens.
Halesia Hispida - The best examples of the tree I know of are in the neighborhood of Cork and Queenstown, but mild climatic conditions such as they exist under there are not essential to their well-being.
Monticola - This grows at low altitudes, and does not appear to ascend to the slopes of the high Appalachian mountains, although the Halesia of those mountain forests was long considered identical with the lowland tree.
The Halesia of the high slopes, however, is a tree often 80 or 90 feet high, with a trunk 3 feet in diameter, sometimes free of branches for a distance of 60 feet from the ground.
There is now every reason to believe that the mountain Halesia will prove one of the handsomest flowering trees of large size which it is possible to cultivate in this climate.