Cubelium Rafinesque ex Britton & A. Brown.
A monotypic genus, a perennial herb, native to eastern North America. "Recent comprehensive phylogenetic investigations of the Violaceae family demonstrated that broadly circumscribed Hybanthus was extensively polyphyletic, and that the sole trait of a bottom petal which was saccate at base failed to delineate natural evolutionary groups (Feng 2005; Tokuoka 2008; Wahlert et al. 2014). The majority of New World hybanthoids formed a well supported clade and were subsequently segregated into the resurrected genus Pombalia on the basis of differences in floral and seed features and anatomical traits (Paula-Souza and Ballard 2014). Our temperate eastern North American native hybanthoid now belongs to the resurrected monotypic genus Cubelium, with the genus and species first validly published by Britton and Brown (1897). It is sister to the very small genus Hybanthus sensu stricto from Mesoamerica and the West Indies, that consists of three species of shrubs and treelets. Our Eastern Green Violet differs from Hybanthus sensu stricto in herbaceous habit, highly reduced cymose inflorescence, and several unique floral, fruit, seed and anatomical features." (Ballard 2020).
Ref: Ballard (2020); Ballard (in prep.); Ballard, Burwell, & Lockhart (2020) In Weakley et al. (2020); Ballard, Paula-Souza, & Wahlert In Kubitzki (2014); Little (2015) In Flora of North America Editorial Committee (2015); McKinney & Russell (2002); Paula-Souza & Ballard (2014); Wahlert et al. (2014). Show full citations.