Plants of the World Online accepts two species, native to Iran, Oman and the Gulf States.

The flowers are small and bisexual, with five tepals, two outer and three inner, the three inner clasping the fruit when it forms.

[2] The genus was erected by Hippolyte François Jaubert and Édouard Spach in 1844.

[3] It is placed in the subfamily Polygonoideae, tribe Calligoneae, along with its sister genus Calligonum.

[4] As of March 2019[update], sources varied considerably in the number of species assigned to the genus.