Ulmus parvifolia 'Emer II' or 'Emerald Vase' (selling name Allee) is a Chinese Elm cultivar selected by Dr. Michael A. Dirr and cloned in the late 1980s from a tree planted circa 1910 on the University of Georgia campus at Athens, that had survived ice-storms undamaged.[1][2] It was patented in 1991.[3]
Allee can reach a height of about 15 m, with a more upright crown shape than its stablemate Athena, its spread approximately 13 m, with arching branches bearing medium green, glossy leaves turning orange to rust red in autumn. [1] The exfoliating, mottled bark has a puzzle-like pattern, and is considered attractive.[3]
The species and its cultivars are highly resistant, but not immune, to Dutch elm disease, and unaffected by the Elm Leaf Beetle Xanthogaleruca luteola.[4] As with the species overall, damage caused by Japanese Beetle is relatively slight (< 8% defoliation).[5]
Allee is reputedly drought tolerant, but in the elm trials conducted by Northern Arizona University at Holbrook, Arizona, it proved unsuited to the hot, arid climate and sustained over 50% mortality in its first year, as did its sibling Athena.[6] The tree is being evaluated in the National Elm Trial coordinated by Colorado State University.[7] With its more upright form, Allee has been described as a better street tree than the commonly planted lacebark elm 'Drake'.[8] It has been planted by the north front of Austin Hall, Oregon State University, Corvallis, Oregon.[1][9] Lines of Allee and Bosque in North Robinson Avenue and North Harvey Avenue, Oklahoma City, flank the Oklahoma City National Memorial.[10] The tree has been introduced to Australia and Europe,[citation needed] and was marketed briefly in England by the Thornhayes Nursery, Devon.
(Widely available)