The phylogenetic context of corolla symmetry in Canscora Lam. (Gentianaceae)

Abstract

Floral symmetries are perceived as an essential structural trait for classification in angiosperms. However, the traditional view of floral symmetries considered only two states—actinomorphic or zygomorphic—often disregarding other forms. This binary view can be onerous, as floral development may involve numerous shifts in symmetry. In the Gentianaceae family, zygomorphy is predominantly regarded as a synapomorphy for Canscora, leading to the segregation of some actinomorphic Canscora species into the separate genus Canscorinella. Additionally, species with slightly zygomorphic forms have been reported, leaving the relationships among various floral symmetries largely unaddressed. To investigate the phylogenetic relations of floral symmetries in Canscora, we analyzed DNA sequence data from nuclear and plastid markers and examined the generic status of Canscorinella. Furthermore, an ontogenetic study was conducted to understand the ancestral floral symmetries in Canscora. Our analyses revealed the independent evolution of zygomorphy in Gentianaceae and the reversal of actinomorphy in Canscora. This study provided insights into the phylogenetic relationship of Canscorinella within the subtribe Canscorinae, suggesting that Canscora exhibits actinomorphy in its early growth stages, which later develops into zygomorphy.