Habit: synoecious or monoecious trees, with mucilage cells
Leaves***: alternate, simple, usually basally oblique, stipules deciduous
Flowers: small, unisexual or bisexual, solitary or clustered in axils
Sepals: 4-8, free or connate
Petals: absent
Stamens: 4-8, opposite sepals
Gynoecium: of 2 connate carpels; ovary superior with 1 locule and 1 apical ovule
Fruit***: a samara (Ulmus) or drupe (Celtis)
Diverstiy: 16 genera / 140 species
Distribution: north-temperate and tropical
Economics: timber trees; cultivated ornamentals (Siberian Elm in Flag)