The common azalea or Pinxter flower (Rhododendron nudiflorum [R. periclymenoides]) is known in many places as the "Swamp apple," because so generally producing upon the tips of the branches swollen masses, large as, and superficially somewhat resembles, green apples, the work of E. Azaleae.
”- Halsted, Byron D.: (1893) Notes Upon a New Exobasidium©