'Marmo' was selected from the collections of the Morton Arboretum, Lisle, Illinois, and named in honor of Margaret Morton. Characteristics include a vigorous growth rate, a strong central leader, excellent branching character, and a uniform upright habit. Fall color is an interesting mottled blend, ranging from combinations of red and green to burgundy, yellow, and gold, depending on temperature changes and site conditions. 'Marmo' is a naturally occurring hybrid between red and silver maples and is being promoted as a more ornamental and desirable alternative to A. saccharinum, and a more adaptable alternative to several cultivars of A. rubrum for heavy clay soils. The parent tree, planted at the Morton Arboretum in the mid-1920s, last measured 70' in height with a 35' spread. Zones 3-8.