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A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Wednesday - April 23, 2008

From: Smithtown, NY
Region: Northeast
Topic: Plant Identification, Shrubs
Title: What is difference between Rhododendrons and Azaleas
Answered by: Nan Hampton

QUESTION:

I am replanting my entire front yard as a native woodland garden (I am on Long Island, NY). I am having a hard time finding native rhododendrons and/or azaleas. I would prefer to remain true to the regions natives, but will any cultivar that I can find locally suffice? Also, I am a bit confused on the issue of rhododendrons and azaleas, They look very different, but have similar Latin names. Can you clarify?

ANSWER:

First, let's clarify the difference between rhododendrons and azaleas. An article from Virginia Cooperative Extension, "Azaleas and/or Rhododendrons", tells us that the main difference is that an azalea has five stamens while a rhododendron has ten. Other differences are: rhododendrons all are evergreen, while azaleas are either deciduous or evergreen; rhododendrons grow larger than azaleas and their blossoms and foliage also tend to be larger. Nevertheless, the botanical taxonomists have put both rhododendrons and azaleas in the same genus, Rhododendron.

The following are the Rhododendron species native to New York:

Rhododendron arborescens (smooth azalea)

Rhododendron calendulaceum (flame azalea)

Rhododendron canadense (rhodora)

Rhododendron lapponicum (Lapland rosebay)

Rhododendron maximum (great laurel)

Rhododendron periclymenoides (pink azalea)

Rhododendron prinophyllum (early azalea)

Rhododendron viscosum (swamp azalea)

You can search in our National Suppliers Directory to find nurseries in your area that specialize in native plants. In a quick preliminary search on nurseries in your area I found Fairweather Gardens in Greenwich NJ that advertised a large inventory of Rhododendron spp. Most nurseries list their plants with the botanical names. If you find any of the species listed above, even though they are a cultivated variety of that species, they should be fine for your area. You would want to avoid using any introduced species (e.g., R. japonicum (Japanese azalea)) or any of the species not native to New York or adjacent states (e.g., Rhododendron austrinum (orange azalea)). You can find a list with maps showing the location of Rhododendron species growing in North America in the USDA Plants Database.


Rhododendron arborescens

Rhododendron calendulaceum

Rhododendron canadense

Rhododendron lapponicum

Rhododendron maximum

Rhododendron periclymenoides

Rhododendron prinophyllum

Rhododendron viscosum
 

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