About 60-70 species including:
Celtis australis - European Hackberry
Celtis bungeana Bunge's Hackberry
Celtis caucasica - Caucasian Hackberry
Celtis labilis - Hubei Hackberry
Celtis koraiensis - Korean Hackberry
Celtis jessoensis - Japanese Hackberry
Celtis laevigata - Southern Hackberry
Celtis occidentalis - Common hackberry
Celtis reticulata - Netleaf hackberry
Celtis sinensis - Chinese Hackberry
Celtis tenuifolia - Georgia Hackberry

Hackberry Celtis is a genus of about 60-70 species of deciduous trees widespread in warm temperate regions of the Northern Hemisphere, in southern Europe, southern and eastern Asia, and southern and central North America. They are generally medium-sized trees, reaching 10-25 m tall, rarely up to 40 m tall.

Previously included either in the elm family Ulmaceae or their own family the Celtidaceae, genetic analysis by the Angiosperm Phylogeny Group has shown they are best placed in the hemp family Cannabaceae.

The leaves are alternate, simple, 3-15 cm long, ovate-acuminate with a long pointed tip, and evenly serrated margins.

The fruit is a small drupe 6-10 mm diameter, edible in many species, with a dryish but sweet, sugary consistency, reminiscent of a date.