Pyramidal Hornbeam is a common columnar tree used for when immediate privacy screening is desired. Commonly used interchangably with the columnar oak. This easy, low maintenance tree maintains its upright columnar shape and provides a dense, green canopy with soft easy to clean leaves. Height 40 ft., Spread 10 ft.
For smaller settings, may I suggest Lucas Pyramidal Hornbeam. Similar tree, but only reaches 25 ft and spreads 6 to 8ft.