A bit of magic happens along the Oregon Coast in April and May—the wild rhododendrons begin to bloom! 

R. macrophyllum comes in a variety of colors from red to white. Photo by R. Prchal used with permission.

Rhododendron macrophyllum or more commonly the ‘Western Rhododendron’ produces a lovely five-lobed, bell-shaped bloom. Imagine 20 or more single pale pink to rosy-purple blooms clustered in trusses that cover a small tree or large shrub with large green leaves. Now imagine miles of blooms peeking out on each side of road.

Local display

Blooms are visible along State Highway 101 typically during late April and early May. Some communities, such as Florence, Oregon, even host an annual festival (May 14-16, 2021) with parades, flower shows, and many family-friendly activities. Festivals and displays, such as these plant festivals, can be a fun and easy expeditions for garden buffs.

History

R. macrophyllum, discovered in 1792, thrives along the Pacific coastline from British Columbia, Canada through northern California. R. macrophyllum was selected as Washington’s State Flower in 1892 (see https://www.worldatlas.com/articles/what-is-the-state-flower-of-washington-washington-state-flower.html ) and is currently being studied by the Rhododendron Species Foundation, in Federal Way, Washington, and local American Rhododendron Society Chapters.

Habitat

R. macrophyllum thrives in disturbed habitats such as roadside embankments and recently deforested wildlands. They can also live in mountainous areas.

If you hear disparaging comments about rhododendrons from Loggers or Foresters it is probably about this plant. Unlike most other rhododendrons, R. macrophyllum (and other plants in the Pontica section) create a very thick undergrowth which can make some terrains nearly impossible to traverse.

Warfare

A few rhododendrons in the Pontica section, like R. macrophyllum, contain a natural neurotoxin (grayanotoxins). Persians and Greeks used this knowledge in warfare, literally using rhododendron honey to over-throw invading armies.

No part or product (such as honey) made from R. macrophyllum should be consumed or used by humans. Do not burn the wood in a campfire–see Texas A&M University at https://research.tamu.edu/2014/11/03/how-eating-mad-honey-cost-pompey-the-great-1000-soldiers/ and Scottish Centre for Infection & Environmental Health (https://www.bmj.com/rapid-response/2011/10/28/honey-poisoning-beware-rhododendron. Bees are not affected.

For more information see: OSU’s College of Agricultural Sciences, Department of Horticulture, Landscaping Plants at https://landscapeplants.oregonstate.edu/plants/rhododendron-macrophyllum and the American Rhododendron Society at https://www.rhododendron.org/descriptionS_new.asp?ID=114.

From https://landscapeplants.oregonstate.edu/plants/rhododendron-macrophyllum
Varieties of Yellow Pond-lilies can be found across the US.

Why is it possible to drown a common house plant and yet there are plants that grow gleefully in water?

The common Yellow Pond-lily has a beautiful bloom and large, heart-shaped floating leaves (nearly 18-inches in length). The bloom is nearly 4-inches and held just above the water surface in spring through early fall.

Survival

The Yellow Pond-lily has developed a specialized type of underwater tissue that helps it survive. This tissue, called aerenchyma, facilitates the underwater movement of large amounts of oxygen and other gasses. This tissue holds eight times the amount of oxygen, compared to a house plant.

Respiration in water lily-type plants is anaerobic (meaning the process occurs without oxygen). Many ponds and slow-moving waters where it grows are often low oxygen. This respiration process creates ethanol (a type of alcohol) within the plant’s cells.

This alcohol is poisonous to the plant. To get rid of the alcohol quickly, the plant evaporates it up through the aerenchyma cells and bloom. The pretty yellow blooms smell strongly of alcohol which attract pollinating flies, and create a small bottle-shaped tuber to store sugars in (explains the common European name of ‘Bandy-bottle’).

Medicine

Yellow Pond lilies have been used in traditional medicines remedies. There are warnings related to tannins and selecting materials from a clean water source (see the Natural Medicinal Herbs website at http://www.naturalmedicinalherbs.net/herbs/n/nuphar-lutea=yellow-water-lily.php). Note: Not all varieties or parts of the Yellow Pond-lily are edible or appropriate for use.

The Edible Wild Food website (http://www.ediblewildfood.com/yellow-water-lily.aspx) reports that the Yellow Pond-lily was a common food source for many Native people. Natives leached the rootstocks collected in the spring and winter of tannins and boiled or roasted for flour. Seeds were often cooked like popcorn. Flowers can make a refreshing drink.

The National Park Service reports Yellow-Pond lily species ‘Nuphar polysepalum’ growing in the Denali National Park/Preserve lowlands in Alaska. When cooked, this variety is also tasty (see Denali National Park, Alaska, https://www.nps.gov/dena/learn/nature/pondlily.htm).

Where to find it

Yellow Pond Lilies grow in a wide variety of aquatic habitats as far south as Baja California, and north into Alaska. Habitat ranges from hot desert ponds to ponds frozen more than half of the year!

Want it?

Propagate Yellow Pond Lilies through seed or division and will grows in containers!

For more information, see Plants for a Future at https://pfaf.org/user/Default.aspx. Image is Royalty free from free-images.com.

The Pacific Coast area has only one native azalea which is famous not only for its fragrance and beauty, but also as being very difficult to grow.

Unlike our native rhododendron R. macrophyllum, R. occidentale is considered to be an azalea or azaleadendron. Both plants have a tendency to grow in thickets and become fairly tall. Unlike R. macrophyllum, R. occidentale is a deciduous azaleadendron and drops all of its leaves in the winter.

Colorful and fragrant blooms

The fantastic, often fragrant blooms, appear when the leaves emerge. Imagine 6-12 five multicolored florets clustered into trusses measuring up to 5-6 inches wide covering a large shrub.

These florets typically flaunt white, orange, yellow, pink or red, with flares, stripes, blotches, and frilly lobes that are deliciously fragrant.

Habitat

The flower and plant diversity reach a peak in the southern Oregon/northern California region spawning creating several unusual, recognized natural selections. This plant is also unusual because it will grow in serpentine soils (which are more base in pH). They are often used for southern coast restoration projects.

R. occidentale was used to develop fragrance and diversity in many other deciduous hybrid azaleas (such as Exbury hybrids). To see or smell a local example on campus check the southwest corner of Nash; southeast of Gilkey Hall at intersection of sidewalks in late April and May.

Where to look

Look for plants growing on the hillsides along Highway 101 from Newport to southern California. Fragrance will also give their locations away.

While it easily grows here, it will not on the East Coast. No one quite understands why it will not grow well there, especially since the bulk of native azealeas grow there.

Natural Cluster

It is possible to view a major natural cluster at the Azalea State Reserve just south of the Oregon-California border (see https://www.stateparks.com/azalea_state_reserve_in_california.html) near to Highway 101. There are several campgrounds, parks, reserves, etc. nearby.

Brookings, just north of this area in Oregon, features an annual Azalea festival. Check out occidentale at the Brookings City Park May 22-25, 2020. The festival includes many activities such as art shows, plant sales, seafood feeds, cruise ins, breweries, much and more! (see http://azaleafestivalbrookings.com/ )

For more information see OSU’s College of Agricultural Sciences, Department of Horticulture, Landscaping Plants at https://landscapeplants.oregonstate.edu/plants/rhododendron-occidentale and the Azalea Society of America at https://www.azaleas.org/view-azalea/?id=9318. Photo of R. occidentale by Don Hyatt, http://donaldhyatt.com/ used with permission.