The relationship of the Apodanthaceae to other plant families remains unresolved, though recent research has given more clarity to the family's position and suggests inclusion in the order
Malpighiales with a possible link to the family
Rafflesiaceae. While the
APG III system of classification (2009) listed the family's taxonomic position as uncertain, the
APG IV update in 2016 assigned it to the
Cucurbitales based on mitochondrial and nuclear DNA sequences. However, two 2024 studies, both of which use large sets of nuclear DNA for analysis, indicate that it is a basal member of the Malpighiales. The difficulty with using
plastid DNA for phylogenetics of the Apodanthaceae was discussed in a 2021 study by Li
et al. This paper refers to the Apodanthaceae as one of five 'problematic' families (along with
Balanophoraceae,
Mitrastemonaceae,
Rafflesiaceae, and
Thismiaceae) and notes that
plastome sequences in these families are highly reduced and they have unusually high substitution rates in the retained sequences, which can hamper proper phylogenetic alignment and cause
long branch attraction artifacts. ==External links==