[2] Its only species is Sigmoidala kityana, native to Myanmar, northern Thailand and Laos.

Individual flowers are 16–20 mm (0.6–0.8 in) long and have the general shape of members of the subfamily Faboideae.

The wing petals of Sigmoidala are unique within the tribe Wisterieae in having a sigmoid shape, bent sharply back at the midpoint before extending forwards again.

[5] As of January 2023[update], Plants of the World Online listed the distribution of Sigmoidala kityana as Myanmar to north and north-eastern Thailand and Laos, growing primarily in the seasonally dry tropical biome.

[1] Compton et al. (2019) state that it only occurs in a narrow region of northern and north-eastern Thailand, where it climbs among dry forest trees in partial sunlight at elevations up to 400 m (1,300 ft).