'Pioneer' is a fast-growing tree distinguished by a dense, globular crown, which as it matures becomes more broad than tall, like its U. glabra parent,[1] and casting a heavy shade.

The leaves are deep green, and similar in shape to the Wych Elm,[2] colouring yellow and red in the fall.

[8] The tree's foliage was adjudged "resistant" to Black Spot by the Plant Diagnostic Clinic of the University of Missouri [3].

[9] 'Pioneer' has had a very limited introduction to Europe,[10] featuring in street tree trials in several Dutch cities in the late 1990s.

The tree has reputedly been planted in Preston Park, Brighton, and along Tisbury Road, Hove, but does not feature in the NCCPG National Elm Collection held there.