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I.D. of old rhododendron?

Posted by jacqueline3 9CA (My Page) on
Fri, Jul 13, 12 at 15:20

Here is a picture of a rhododendron that has been growing, I estimate, in our old garden since the 1930s or 1940s. The house has been in my family since 1905, and there was a formal garden since then, although parts of it are now very overgrown or wild.

So, any guesses as to the identity of this beautiful old rhododendron?

Thanks a lot for your help -


Follow-Up Postings:

RE: I.D. of old rhododendron?

I don't have any idea, but for what it is worth, here couple photos of the native West Coast native rhododendron, R. macrophyllum:

As with most species, it has some natural variation in flower color from plant to plant. Among the coast redwoods, the macrophyllum's bloom time is typically late May to mid June. There can be a 2 to 3 week variation some years. Some in Jedediah Smith Redwoods State Park seem to bloom earlier.

RE: I.D. of old rhododendron?

Thanks. I looked up zillions of pictures of rhododendron macrophyllum, and they were invariably pink, and fat fluffy clusters, like your picture. Mine are invariably light purple, and the flower clusters are sort of wispy, as in the picture I posted. As our garden was planted on a bare city lot in 1905 and later, I'm sure our plant was planted on purpose by one of my husband's ancestors, so it could have been any rhododendron available in local nurseries at that time.

Ours is growing in partial shade under a high tree canopy. It blooms usually in late April or sometime in May. It got no care whatever for decades - our climate is so benign, I guess it just likes it here.


RE: I.D. of old rhododendron?

From your picture, all I can see is the color. The detail of the flower is not clear. Macrophyllum has great variation in color from white to light purple. Usually the more unusual forms like white and light purple are the ones that were propagated for garden use.

Most hybrids were hybrids of catawbiense, maximum, or ponticum. These plants provided hardiness when used in hybrids. In 1905 there were not nearly as many varieties as we see today, but still there are many possibilities that could match the color of your plant. Knowing the time of bloom, the location of the plant, and a good photo of the flower would help narrow it down to fewer possibilities.

Here is a link that might be useful: Some Light Purple Rhododendrons

RE: I.D. of old rhododendron?

Thanks, rhodyman. Just wondering, do you know of any heritage or heirloom rhododendron groups, as there are for iris and roses?

To answer your questions, this plant is growing in the No San Francisco Bay Area (Mediterranean climate - warm dry summers & cool wet winters). It blooms, as I recall, in early May. It is growing in partial shade, under trees.

It is not blooming now - next year I will try to take better pictures. Here is the only other picture I have of it - maybe if you copy it to your computer you could zoom it or make it bigger to see the flowers better - that works on my Mac, but perhaps not all computers can do that.

Thanks again for your help.



RE: I.D. of old rhododendron?

The bloom time of your plant rules out most maximum hybrids. That leave catawbiense and ponticum hybrids as the most likely. There are many of both. The date

The first hybrid rhododendrons date back to 1817. To see the progression of rhododendron hybridization from 1817 to 1867, visit First 50 Years of Hybridization. Here are some old hybrids that have a color similar to your:

R. Bluebell (A. Waterer, 1880)

R. Catawbiense Boursault (old standard variety)

R. Catawbiense Grandiflorum (A. Waterer, 1850)

Lee's Best Purple (J. Lee, before 1851)

Purpureum Elegans (H. Waterer, 1850)

Lee's Dark Purple (J. Lee, before 1851)

Purpureum Grandiflorum (H. Waterer, 1850)

RE: I.D. of old rhododendron?

Thanks so much! I will definitely visit that site.

Just one comment on bloom time - I have noticed over 25 years of gardening that most plants bloom earlier here in Cal than they do on the East Coast, Midwest, or the UK. My earliest roses start blooming in Feb. Even types that only start blooming on the East Coast in May/June bloom here in April. Bulbs ditto. Our fruit trees all over the county bloom in Feb/March. Our acacia trees all bloom in Jan, whereas I saw one (an import, of course) blooming in Pa in June! I'm not sure if it is a function of our rains in Nov/Dec breaking the 6 month summer drought, or light, or warm temps, but it is a fact. So, I am not sure that bloom time is a good indicator to use for identifying. So, I am going to keep an open mind on that score.

Thanks again for all of your help -


RE: I.D. of old rhododendron?

You are 100% correct about the time of bloom varying with latitude, altitude, climate and weather patterns. R. maximum is a late June, early July bloomer in most temperate climates. Spring bloomers seem to vary much more than the summer bloomers, but I have no idea when it would bloom for you. Maximum flowers are easy to identify, the flowers are small on a large plant and the 5 petals of each flower form a unique star shape:

R. Maximum Roseum

There is a R. maximum var purpureum that I don't have a photo of.

RE: I.D. of old rhododendron?

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Tue, Sep 25, 12 at 15:23

It's Rhododendron ponticum, probably brought onto the site as a rootstock for a hybrid rhododendron which may now be gone. Before the use of cuttings became the norm hybrid rhododendrons were grafted, older plantings here are full of R. ponticum rootstock sprouts, often mixed with persisting branches of the rhododendrons that were grafted onto them.

RE: I.D. of old rhododendron?

  • Posted by botann z8 SEof Seattle (My Page) on
    Tue, Oct 9, 12 at 17:51

Yup, looks like a common Ponticum to me. A real weed in some parts of the UK. A tough plant all around.
I happen to like it, despite it being very common here.

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