[2][4] The family was formerly sometimes treated to include the hackberries, (Celtis and allies), but an analysis by the Angiosperm Phylogeny Group suggests that these genera are better placed in the related family Cannabaceae.

[4] It generally is considered to include ca 7 genera and about 45 species.

[6] The family is a group of evergreen or deciduous trees and shrubs with mucilaginous substances in leaf and bark tissue.

The leaf blades are simple (not compound), with entire (smooth) or variously toothed margins, and often have an asymmetrical base.

Modern molecular phylogenetics suggest the following relationships:[6][7][8][9][10] Cannabaceae (outgroup) Holoptelea Ampelocera Hemiptelea Zelkova Ulmus