Past literature classified Diapensiaceae as an old family, without defining the meaning of old. The name
Diapensia was given to
Diapensia lapponica by
Linnaeus. Previously, it was the Greek name of
sanicle. The family, originally including only
Diapensia lapponica, was named by
Heinrich Friedrich Link in 1829. Concerning the interrelationships in Diapensiaceae, debate still remains regarding the recognition of
Schizocodon and whether it should be separate from
Shortia. However, recent molecular studies support the split of the two genera. Over time, various relationships among Diapensiaceae and other angiosperm families have been proposed. Previously, it was placed within the order Rosales, as well as in the
Cornales. Diapensiaceae was also placed in an order of its own in the
Cronquist system and by
Takhtajan. Recent studies have placed Diapensiaceae as part of the
Ericales clade, belonging to the "styracoids" (Diapensiaceae,
Styracaceae,
Symplocaceae). It is estimated that Diapensiaceae diverged from Sytracaceae about 93 million years ago. The family is thought to have originated in the Northern Hemisphere. ==Distribution==