rhododendron [M16th] Rhododendron means ‘rose tree’ from Greek rhodos ‘rose’, also found in the name Rhoda, and dendron ‘tree’ found in many plant names as well as in dendrochronology [E20th], the science of dating things through tree rings. Rhododendron was originally used of the rose-flowered oleander which explains its name, and only transferred to the modern plant in the mid 17th century.