Rhododendron sect. Rhodora

Rhodora was a section of subgenus "Pentanthera" in the genus "Rhododendron", that has since been discontinued. It comprised two species, both deciduous shrubs native to eastern North America:
Description.
The section was closely related to sect. "Pentanthera", differing from it in the flower corolla having only three lobes, rather than five, the upper three lobes of sect. "Pentanthera" being joined into a single three-lipped lobe in sect. "Rhodora".
Taxonomy.
The distinct floral structure resulted in Rhodora being treated as a distinct genus at one time. Treating it as such though resulted in the remainder of the genus "Rhododendron" being paraphyletic. However detailed phylogenetic analysis revealed that "Rhodora" was not a distinct entity, but rather polyphyletic, and it was disassembled, each species being allocated to other sections. "Rhododendron canadense" was moved to section "Pentanthera", subgenus "Hymenanthes" and "Rhododendron vaseyi" was moved to section "Sciadorhodion", which then became a new section of subgenus Azaleastrum.