Views on the beauty of rhodora are divided. It is beloved in New England, where it is the most common and widespread of the rhododendron clan, but the description of this species at the Ladybird Johnson Wildflower Center in Texas begins “Rhodora is a rather scrawny, erect-branched shrub that seldom grows over 3-4 ft. tall.” In contrast, Chris Mattrick, writing for the National Forest Service, feels “Never has a more strikingly beautiful plant received such a ho-hum name: Rhodora.”
Ralph Waldo Emerson was transfixed by the flowers, which are a purplish-pink and emerge before the leaves do. His eponymous poem ends with the line, “The self-same power that brought me there, brought you.” Emerson is making the then quite heretical statement that there is nothing special about human beings; all of God’s creations are equal.
I first encountered the rhodora on Mount Toby in western Massachusetts (just north of Sunderland). While they are most often found in wetlands, rhodora is also known to occur on tops of mountains. Mt. Toby is not particularly tall and certainly isn’t bald on top, which apparently encourages the rhodora, but I found it there among the wood lilies. There were only isolated individuals in the understory. Photographs of rhodora in wetlands often show them to be in solid stands taking up part of an acre.
In addition to the divided opinion regarding its aesthetics, the classification of rhodora has changed over the years. Its flower is different from those of other rhododendrons. The bloom of the rhodora is zygomorphic (bilaterally symmetrical) with three fused petals above and two free ones below, while those of rhododendrons are radially symmetric with five petals of equal size. Typical rhododendron petals are also fused into a tube, while those of rhodora are split right down to their bases. Finally, rhodora flowers have seven to 10 stamens, while other rhododendrons have five.
In the 19th century it was called Rhodora canadense (and many other names), but it is now included in the genus Rhododendron. Molecular studies have shown rhodora to be related to other deciduous rhododendrons like flame azalea (R. calendulaceum). In the 21st century it has been placed in the subgenus Pentanthera section Rhodora. While most rhododendron species have 26 chromosomes, rhodora has only 24 and also has a lot less DNA than most other rhododendrons.
True to its trivial name this is the azalea/rhododendron with the northernmost range. It is found in the Appalachians from northeastern Pennsylvania and New Jersey through New England and up into the Canadian Maritimes, including Newfoundland. It flowers in late April in the southern part of its range and finishes in June in the north. Once it has finished flowering rhodora “fades into the background,” with bluish-gray green leaves that are unlobed and untoothed (like all rhododendrons). By the autumn its orange-brown seed cases once again bring it out of the background.
Given the vogue for planting native species in your yard, you will not be surprised to find that rhodora is occasionally available at nurseries. You can find a white-flowered variety, but there are no cultivars. The challenge of maintaining them is apparently to keep them wet enough (but not too wet). They require constantly moist soil, but they are never found growing in the water (as some other ericads can and do). It is apparently even exported to Europe. One site in Finland notes that it is the northernmost azalea and “rhodora would be suited best to moist, even occasionally wet areas in massed plantings, or in near natural woodland settings, where its smaller flowers come into their own without the competition of the commercial varieties.”