Triumph Elm, a hybrid American Elm tree developed by the Morton Arboretum in Chicago. Hybrid American Elms are trees that are created by crossbreeding American Elms (Ulmus americana) with Asian Elms, such as Chinese Elms (Ulmus parvifolia) or Siberian Elms (Ulmus pumila). These hybrids are developed to create trees that are resistant to Dutch elm disease, which is a fungal disease that has devastated American Elm populations in many parts of the world. The Morton Arboretum has developed several different hybrid American Elm varieties, and it sounds like the one you are describing has an exceptional growth rate and attractive leaf color. American Elms are known for their strong wood, which makes them resistant to breakage and makes them a good choice for planting near buildings. They are also popular for their attractive vase-shaped form and their beautiful, lush canopy of green leaves.