This genus is synonymous with the genus Rhododendron. Ledum at one time contained 8 species of evergreen shrubs that are native to very cold areas in the Northern Hemisphere. Taxonomists have recently changed the classification so that this genus is now a subgenus within Rhododendron.

Note: As people named newly identified plants down through the centuries, there were often cases where the same plant was given two or more different names by different taxonomists. The rule is that the first name that was publicly displayed in a book or other publication takes precedence. Once an "accepted name" has been established, all the other names are then referred to as synonyms.