Description from Flora of China
Butneria Duhamel du Monceau.
Lianas, shrubs, or subshrubs, rarely small trees. Stems armed or unarmed (in Flora area). Leaves simple, stipulate, petiolate; leaf blade various shapes, but usually orbicular or ovate; foliar nectaries present. Inflorescences axillary, cymes. Flowers bisexual, small. Sepals 5, connate at base. Petals 5, base clawed, upper part deeply concave, apex with long narrow appendage. Stamens 5, opposite petals; filaments connate into tube; anthers 2-celled, extrorse; staminodes 5, lamellate, apex obtuse, alternate with staminodes. Ovary sessile, 5-celled; ovules 2 per cell, anatropous, lower one aborted; style united almost to apex; stigma apical, inconspicuous or 5-lobed. Capsule globose, spiny, septicidally and loculicidally or only septicidally dehiscent into 5 valves, valves falling from axis. Seeds 1 per locule; endosperm absent; cotyledons foliaceous, 2-lobed.
The genus name has often been incorrectly spelled as "Buettneria."
About 130 species: mostly in tropical America, also Africa, SE Asia, Madagascar; three species in China.