The APG II system, of 2003, does recognize this family and assigns it to the clade monocots, unplaced as to order. This family then consists of two genera Japonolirion and Petrosavia. In circumscribing the family in this way, APG II departs from the APG system, of 1998, which treated each of these genera as constituting its own family. The APG III system, of 2009, place family Petrosaviaceae in order Petrosaviales.
Japonolirion is taken to consist of one species and Petrosavia of three species. The plants in both genera are found in high-elevation habitats and have bracteate racemes, pedicellate flowers, six persistent tepals, septal nectaries, three nearly distinct carpels, simultaneous microsporogenesis, monosulcate pollen, and follicular fruits.
- Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013-06-26.