It includes 12 species native to the eastern Himalayas, Indochina, southern China and Taiwan, and Peninsular Malaysia.

Species of Callerya are scrambling climbers, growing over rocks or shrubs, reaching 0.5–1 m (1.6–3.3 ft) high.

The individual flowers are 11–25 mm (0.4–1.0 in) long and have the general shape of members of the subfamily Faboideae.

Revisions by Geesink in 1984 and by Anne M. Schot in 1994[3] resulted in the genus being expanded, which continued until 33 species were recognised by 2016.

[3] A 2019 molecular phylogenetic study showed that as then circumscribed, Callerya was not monophyletic, nor did it belong in Millettieae.

Instead a reduced genus was placed in an expanded tribe Wisterieae, where it formed a clade with Afgekia, Kanburia, Serawaia and Whitfordiodendron, as sister to the other genera.

Other species which appeared to be in Callerya were not included in the study, so the exact boundaries of the revised genus were not settled.