The American Elm cultivar Ulmus americana 'Iowa State' was cloned in the 1980s from a tree discovered by Professor Alexander (Sandy) McNabb of Iowa State University as the sole survivor in 40 acres (16 ha) of diseased elm at Burlington.^[1]

The tree is possessed of a fastigiate, thickly-branched habit, but has relatively weak branch unions owing to acute angles of attachment leading to bark inclusions.

'Iowa State' was reported in the American Horticulturist News Edition, 63(5):4, 1984, as "a natural selection from southeastern Iowa, highly resistant to Dutch elm disease when inoculated". The species as a whole is highly susceptible to Elm Yellows; it is also moderately preferred for feeding and reproduction by the adult Elm Leaf Beetle Xanthogaleruca luteola,^[2] and highly preferred for feeding by the Japanese Beetle Popillia japonica ^[3][4] in the United States. U. americana is also the most susceptible of all the elms to verticillium wilt.^[5][6]

The cultivar was trialed in Minneapolis.^[1] One of the original plantings (1978) in the Dean Park area of Minneapolis had to be felled in 2012, 34 years later, after serious defects developed.^[7]