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U.S. Forest Service

Plant of the Week

Rhodora (Rhododendron canadense)

By Chris Mattrick

Map of the United States showing states. States are colored green where the species may be found. Range map of rhodora. States are colored green where the species may be found.

rhodora flower Unlike its brethren in the genus Rhododendron the individual petals of the rhodora flower do not unite into a tube but remain separate all the way to their base. Photo by Eleanor Saulys.

rhodora flowers In a forest of muted grays and greens the brilliance of the bloom of rhodora is a sight to behold and savored. Photo by Janet Novak.

rhodora shrub without flowers displaying the leaves Once rhodora has spent the beauty of its blooms, it retreats into the background of the forest's muted greens of summer. Photo by Janet Novak.

Never has a more strikingly beautiful plant received such a ho-hum name: Rhodora. Although it may sound exotic, once the scientific name is revealed it is obvious from whence the common name arose. Yet, the name is a remnant of what was once a distinct genus. In the 19th century unable to justify inclusion of the species in the genus Rhododendron, taxonomists of that age placed this species in a genus unto itself: the genus Rhodora. Today, that decision has been reversed but the old genus name is retained in the common name of Rhododendron canadense, or Rhodora, a member of the Heath (Ericaceae) Family. This is a species that has become part the botanical identity of generations of New England botanists from Asa Gray to Merritt Fernald to Arthur Haines. Its name and image are even used as the logo for the prestigious New England Botanical Club, whose quarterly journal "Rhodora" has been published continuously since 1899.

Perhaps it is the adaptability and beauty of this species that has embossed it into the botanical consciousness of northeasterners. Ranging from Pennsylvania and northern New Jersey to northward to Ontario, Quebec and the Canadian Maritimes, the blooming of this species is sure sign that summer is not far off. Rhodora is a species of great plasticity within its range. Mass explosions of pink erupt in lowland wetlands and swamps beginning in mid- to late May. In these locales the species is more noted for the abundance of its bloom than the beauty of the individual flowers. The shear mass of color is a result of the flowers appearing prior to, or along with the emergence of the leaves. So unlike most other members of the heath family there are no leaves to interfere with our observation of the flowers.

By mid-June, flowering has moved north to the higher elevation areas of northern New England and Canada, where the species still occupies wetlands, but is also found along trails and on the barren summits of mountains. To the spruce weary hiker, this species is a welcome infusion of color into a sometimes drab gray/green environment. It is in the higher elevations, where the species does not grow in such profusion that the individual beauty of the blooms can be more fully appreciated. The flowers are not subtle when closely viewed, but bold. Unlike other members of the genus the flowers have no true tube or throat which would confine all the various plant parts together. Instead it the flower is split almost from its base with an upper three-lobed lip and two lateral strap-shaped petals. The protruding stamens, styles and stigmas are large even for this genus and often equal or exceed the length of the petals.

The flowers also provide nectar to a variety of invertebrate species including the bog elfin butterfly whose caterpillars feed exclusively on the needles of black spruce (Picea mariana). As the life cycle of the bog elfin progresses, the flowers of Rhodora provide a nearby source of food for the newly hatched butterflies. Despite the intense beauty and value of the flowers to the bog elfin and other butterflies, they have no discernable scent unlike other closely related members of this genus.

This shrub rarely exceeds three feet in height and once the flowers have passed it fades into relative obscurity with other woodland and wetland species becoming larger and showier as the season progresses. To the discerning eye, Rhodora can always be identified by its bluish green leaves and presence of a light coating of down on its young stems and leaves. The fruit ripens to a hard ridged capsule that splits open laterally allowing the autumn and winter winds to disperse the dust like seed.

The transcendentalist poet, Ralph Waldo Emerson was so taken with this species in 1839 he penned an entire poem in its honor.

The Rhodora

by Ralph Waldo Emerson

On being asked, whence is the flower?

In May, when sea-winds pierced our solitudes, I found the fresh Rhodora in the woods, spreading its leafless blooms in a damp nook, to please the desert and the sluggish brook. The purple petals, fallen in the pool, Made the black water with their beauty gay; Here might the red-bird come his plumes to cool, And court the flower that cheapens his array. Rhodora! If the sages ask thee why this charm is wasted on the earth and sky, tell them, dear, that if eyes were made for seeing, Then Beauty is its own excuse for being: Why thou wert there, O rival of the rose! I never thought to ask, I never knew: But, in my simple ignorance, suppose the self-same Power that brought me there brought you.

1834 [1839]

For More Information


Ahmadjian, Vernon. 1979. Flowering Plants of Massachusetts. University of Massachusetts Press, Amherst, Massachusetts.

Emerson, Ralph Waldo. 1834. The Rhodora. American Transcendentalism Web.

Appalachian Mountain Club. 1964. AMC Field Guide to Mountain Flowers of New England. Appalachian Mountain Club, Boston, Massachusetts.

Gleason H. A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition. The New York Botanical Garden, New York, New York, USA.

Johnson, Charles W. 1985. Bogs of the Northeast. University of New England Press, Hanover, New Hampshire and London, England.

Slack, N. G. and A. W. Bell. 1995. Field Guide to the New England Alpine Summits. Appalachian Mountain Club, Boston, Massachusetts.

Wallner, J. and M. J. DiGregorio. 1997. New England’s Mountain Flowers: A High Country Heritage. In cooperation with the New England Wild Flower Society. Mountain Press Publishing Company, Missoula, Montana.

Wikipedia, The Free Encyclopedia. Rhododendron canadense. 2006.