Coefficient of Conservatism:
Coefficient of Wetness:
Floodplains, river bottoms, and swamps.
A scarce small tree; the very large, usually unlobed leaves are suggestive of a large leaved Tilia. The leaves are dull, and sometimes scabrous above and, at least in Michigan collections, the largest leaves especially are somewhat different in shape than those of Morus alba, with the widest point nearer the middle of the leaf, gradually tapered to the apex, then abruptly contracted to an acuminate apical "tail."
In Ontario, studies have shown that the small, isolated populations of Morus rubra are threatened by hybridization with the common M. alba (Burgess & Husband, 2006). Michigan specimens that may be putative hybrids have been seen from Berrien, Genessee, Kalamazoo, Lenawee, Macomb, Ottawa, and Washtenaw Cos. These have leaves that can be quite large, like Morus rubra, and often mostly unlobed, even on rapidly growing shoots, but unlike M. rubra, even the largest leaves taper more gradually from a widest point, nearer the base to the tip, lacking the conspicuous abruptly acuminate "tail" of M. rubra. The leaves of putative hybrids are also more or less smooth and sometimes even shiny above, and usually sparsely pubescent or with only pustules between the main veins beneath.