Triplateia, Ord. Nat. Pl.: 305. 1830 sec. Dillenberger & Kadereit (2014)
- Type: Triplateia diffusa
- =Hymenella, Prodr. 1: 389. 1824, nom. illeg., syn. sec. APG III (2009) [non Hymenella]
Monotypic; endemic to central Mexico. Treated by McNeill (1962) as Minuartia subg. Hymenella, Harbaugh & al. (2010) and Greenberg & Donoghue (2011) both reported it as sister to Geocarpon minimum Mack., a species endemic to the Ozark region of the United States. Dillenberger & Kadereit (2014) found that it was a sister taxon to three species of Stellaria from Mexico and the Caribbean. This clade was, depending on the gene chosen, either sister to Mononeuria (Minuartia sect. Uninerviae + Geocarpon) (matK) or sister to a clade including Schiedea, Wilhelmsia, and Honckenya (ITS).