[3][4] 'Nigra' is not mentioned in either Elwes and Henry's[5] or Bean's[6] classic works on British trees.
Though 'Nigra' is sometimes listed as a synonym of 'Cinerea' (see 'Synonymy'), the leaf-descriptions of the two cultivars appear to distinguish them, the latter having leaves recalling those of Exeter Elm.
[2] Robertson stated that 'The Black Irish Elm' took its name from its dark chestnut-coloured young shoots, and that it made a slender, erect tree when old.
[1] Loudon described the tree as of moderate size, with a spreading habit like wych elm, but comprising rather irregular, contorted branches bearing much smaller, more rugose leaves,[3] of a much deeper green than the species.
[9] U. montana nigra was introduced to the Dominion Arboretum, Ottawa, Canada, probably from Späth, in 1899.