Blossfeldia is a genus of cactus (family Cactaceae) containing only one species, Blossfeldia liliputana,[1] native to South America in northwestern Argentina[2] (Jujuy,[3] Salta, Tucumán, Catamarca and Mendoza Provinces)[4] and southern Bolivia[2] (Santa Cruz and Potosí Departments).

[citation needed] It is of note as the smallest cactus species in the world, with a mature size of around 10–12 mm diameter, solitary or with many dark green stems forming colonies in the fissures of the rocks, it does not have ribs or tubercles, nor spines.

[2] Blossfeldia liliputiana has several features making it unique among cacti, including a very small number of stomata, the absence of a thickened cuticle, and hairy seeds with an aril.

[2] However, molecular phylogenetic studies have repeatedly shown that it is sister to the remaining members of the subfamily, and well removed from other genera placed in the Notocacteae:[6][7] Blossfeldia tribe Cacteae core Cactoideae, including traditional members of tribe Notocacteae Nyffeler and Eggli, in their 2010 classification of Cactaceae, accepted tribe Blossfeldieae as outlined by Crozier,[8] within Cactoideae.

[9] Earlier, Blossfeldia was considered as a distinct genus within the tribe Notocacteae;[2] it had even been placed in an entirely separate subfamily, Blossfeldioideae.