Native Rhododendrons of Oregon's Boletim

25 de agosto de 2021

White-flowered Rhododendron (Rhododendron albiflorum)

We went for a hike on August 23, 2021 to Umbrella Falls, Mount Hood, Mount Hood National Forest starting at the Elk Meadows Trailhead and then up to the falls on the Umbrella Falls Trail. Two known small patches of R. albiflorum were noted along Elk Meadows Trail at an elevation of about 4550 ft in rills (small gullies) above (west of) the trail. A third patch, at an elevation of about 4575 ft, was noted a hundred or so yards west of the Elk Meadows Trail north of the Umbrella Falls Trail. And finally a fourth patch as noted at about elevation 5125 near the Hood River Express ski lift.

At the first location north of the Elk Meadows Trailhead parking flowering had taken place as evidenced by many fruiting bodies. A good photo was obtained showing the location of this year's flowers on the stem above last year's seed pods. R. albiflorum is unique among Rhododendrons in that flowering takes place on the previous year's stem, and not from a terminal bud as in other Rhododendrons. see:
No flowering was evidenced at the 2nd location. see:
At the third location on the lower Umbrella Falls we noted foliage eaten by caterpillars, aphids, and later with microscopic investigation spider mites and an interesting large aphid, as well as two ubiquitous (for R. albiflorum) fungal infections. see: which includes links to additional related observations.
The fourth and highest elevation observation on 8/23/21 (see: and: ) had plants growing in full sun in the ski runs and plants growing in shade. Those growing in conditions with more light have leaves that tend to have wavy/crinkly appearances, while those growing in shadier conditions have leaves that are flat.

Publicado em 25 de agosto de 2021, 08:56 PM por geographerdave geographerdave | 0 comentários | Deixar um comentário

16 de agosto de 2021

Pacific Rhododendron (Pacific Rhododendron)

There is quite a bit of variation within Pacific Rhododendron. DNA studies indicate there are about 4 clades in plants sampled from north+western California , north to Canada. See;
Prior to that two members of the American Rhododendron Society explored the Oregon Cascades near Detroit, Oregon for a few years trying to find plants with color variations. Their, and others', findings indicate the color of Pacific Rhododendron can range from white to dark pink. Summaries of, including photographs of color variations, their field trips can be found in the Journal of the American Rhododendron Society:

Publicado em 16 de agosto de 2021, 01:00 AM por geographerdave geographerdave | 0 comentários | Deixar um comentário

14 de julho de 2021

White Flowered Rhododendron distribution in Oregon

I've been hoping to explore the range of R. albiflorum in the Oregon Cascades this year, hoping to answer the question does it still exist in areas where it has been collected, and what is the health of those populations? The Consortium of Pacific Northwest Herbaria website ( ) was used to find location data, including as follows:
Clackamas County: Veda Lake
Jefferson and Marion Counties: Olallie Lake Scenic and Mount Jefferson Wilderness Areas.
Linn County: Forest Road 2234, Bruno Meadows, Willamette National Forest and Bachelor Mountain.
Lane County: Scott and Scout Lakes, Indian Ridge, Middle Sister
Deschutes County: Bachelor Butte.
Grant County (?): Mount Ruth.

There are many recent reports on iNaturalist of the species around Mount Hood and Mount Jefferson areas and a few from the Elkhorn Mountains. In the Cascades there aren't any recent reports of the species south of Mount Jefferson; and none in the Wallowa Mountains of northeast Oregon. Does the species not exist in the Wallowas? see:

Much of the area around Mount Jefferson was seriously burned in 2020 from the Lionshead Fire so access to the area will be problematic for possibly several years. Since fires may be a continuing issue for quite awhile I am hoping that observers will make note of where they find R. albiflorum in Oregon, and post those observations on iNaturalist.

Publicado em 14 de julho de 2021, 05:53 PM por geographerdave geographerdave | 0 comentários | Deixar um comentário

29 de junho de 2021

Health of wild native rhododendrons post June 2021 massive heat wave

I am hoping people will observe and make observations on how our native rhododendrons faired in the heat wave that hit Oregon at the end of June 2021. There are always some plants that are infected with fungal infections, insects, or in general not doing well. But in general how did our native plants fare? There will be damage and most plants should recover, but it is important to note how plants are doing.

Publicado em 29 de junho de 2021, 05:01 PM por geographerdave geographerdave | 0 comentários | Deixar um comentário

07 de abril de 2021

Guidebook to Avalable Rhododendrons

For anyone wanting to see a book that is profusely illustrated with species, and hybrid (cultivar) rhododendrons I would recommend, the now out-of-print, "Greer's Guidebook to Available Rhododendrons" by Harold E Greer. There are several editions, which can be found on line on ebay, amazon, etc. This is not a key that will tell you what species, or hybrid, you are looking at, but it will show the variety of hybrid varieties exist, especially in gardens and urban areas.

Publicado em 07 de abril de 2021, 08:23 PM por geographerdave geographerdave | 0 comentários | Deixar um comentário

25 de janeiro de 2021

2021 Goals

Thank you to everyone who has recorded Oregon's wild native rhododendrons. Despite COVID-19 keeping me close to home in 2020 I was still fortunate enough to be able to wander around northern Oregon and southern Washington Cascade Mountains in search of native rhododendrons. During my day trips from Portland I also recorded a variety of other plants, and insects.

Several of the areas I visited in 2020 were impacted by the Lionshead Fire. It is currently unknown whether or not any of the areas impacted by last year's fires will be accessible in 2021. But, it will be interesting to see what impact the fires had.

In 2021 I would like to continue exploring the northern Oregon Cascades and contribute further to mapping out the range of R albiflorum, R menziesii and of course R macrophyllum.

Publicado em 25 de janeiro de 2021, 07:03 PM por geographerdave geographerdave | 0 comentários | Deixar um comentário

14 de setembro de 2020

Oregon's Native Rhododendrons and Fire

The Native Rhododendrons of Oregon Project was started to record and monitor the distribution of our native rhododendrons. In-light-of climate change it is important to know where they live and see what impacts the changing climate is having on them. The Project is also a chance to monitor pathogens which impact Rhododendrons, like Sudden Oak Death which is not native to the west coast.
For example, the White-flowered Rhododendron is found in a limited area of north-east Oregon but is more common and widespread in the northern Oregon Cascades, where it has been reported on iNaturalist as far south as Bachelor Mountain in Linn County. Around Mount Hood I have found it above 4200 feet, and up to 6,000 feet. There isn’t too much real estate on Mount Hood, or anywhere else in Oregon for that matter, above 6,000 foot elevation. An immediate question is what happens to plants at the lower elevations in their range? Do they die out, especially on the lower elevation mountains they are currently found on? Do they survive in a much-reduced range only around springs, or lakes?
What about the Pacific Rhododendron? It is very common in the northern Oregon Cascades where it can grow in large impenetrable thickets. Why is it so rare north of the Columbia River in Washington State? It is present in Skamania County just to the north, but in widely scattered locations. What factors limited its distribution there? What about Rhododendron columbianum? Why is that plant not found in the Oregon Cascades, but is found on either side in Washington’s Cascades and in California’s Sierra Nevadas?
As summers continue to heat up, and as the fire season continues to lengthen how well will the Rhododendrons recover from the large fires that this season are unfortunately creating havoc all over the west coast? At what point does the environment stop supporting the Rhododendrons? We will only find out by finding them throughout their range and monitoring them.
Late this summer, August 23-25, 2020, we went into eastern Marion County north of Mount Jefferson and spent three days looking, and finding R macrophyllum, albiflorum, and one small population of R menziesii. See:
Since Labor Day weekend when Oregon experienced a rare late summer wind event that was analogous to the Santa Ana winds of southern California. The strong east winds caused existing fires, especially the Lionshead and Beachie Creek fires which were started by lightning strikes, to significantly expand. The Lionshead fire has seriously impacted the entire area we explored just a short time prior.
The continued spread of the Lionshead and other fires can be monitored on such websites as
As depressing as the current conflagration is it will be interesting to monitor the burnt areas and see how Rhododendrons (and other plants) reestablish themselves. One area that can be looked at to see what might happen is the north slope of Mount Hood where three significant fires occurred between 2006 and 2011. I have started photo albums on flickr to record trips taken to areas that were, and now, impacted by wildfires.

Publicado em 14 de setembro de 2020, 11:43 PM por geographerdave geographerdave | 0 comentários | Deixar um comentário