Rubber Production on the High Plains?

By Scott Aker

Ericameria nauseosa in flowerIt seems that as I continue my career in horticulture, there are plants that I come back to over time. With my recent move to Wyoming, I have come back to a lot of plants that are familiar from my childhood in western South Dakota. One of those is rubber rabbitbrush, Ericameria nauseosa. When I first learned it, it was Chrysothamnus nauseosus, but taxonomists assigned it to a different genus. I first knew it from visits to Badlands National Park where it grew as a low, billowy shrub among the desolation of nearly white decomposed Pierre Shale.  

Ericameria nauseosa bright yellow flowersFast forward to last fall when I arrived in Cheyenne to look for a new home. It had been a dry year, as they often are here, and anything that was not watered frequently was dormant and brown. Rubber rabbitbrush, however, had burst into bloom with its golden flowers covering each defiantly green shrub. I passed by one home with much of its front yard devoted to the shrub, and upon close inspection, I discovered that the stems were an attractive shade of green. The ones I knew from South Dakota had gray stems. It turns out there are two subspecies—Ericameria nauseosa ssp. consimilis has green stems and is more western in its distribution, while Ericameria nauseosa ssp. nauseosa has gray stems and is more eastern.

Ericameria nauseosa foliageThe species name refers to the smell of the foliage when crushed. It is described as pineapple-like by some and as foul and rubbery by others. While the scent may depend on the sniffer, the fact that the whole plant contains rubber in high amounts is beyond doubt. As early as World War II, it was studied as a potential domestic source of rubber when much of the world’s rubber production fell into Japanese hands. It is a small source of industrial rubber today. Perhaps one of the factors limiting its use as a source of rubber is the long time of six years that it takes for the plant to reach a stage of maximum rubber content. Curiously, the rubber found in rubber rabbitbrush is not in the form of latex; it is rather in the form of solids in the inner bark and outer ring of xylem just inside the bark. Ericameria nauseosa ssp. consimilis may have up to 4% rubber by dry weight, double the amount for Ericameria nauseosa ssp. nauseosa. The rubber from rubber rabbitbrush is also free of the proteins that cause problems for those with allergies. 

Ericameria nauseosaI was interested to learn why rubber rabbitbrush is only of minor commercial importance. It turns out that guayule, Parthenium argentatum, was designated as “the official crop for domestic production of rubber” (Bowers, 1990) even though it is not as cold hardy as rubber rabbitbrush. Even plants cannot escape politics.  Perhaps it is the six years needed to reach peak rubber production. It may also be the quality of the rubber, which is judged by the molecular weight of each carbon chain; longer chains and higher molecular weight are desired. Rubber rabbitbrush does not have the highest molecular weight (Ma, 2019), and that may be why it is not widely grown or harvested for commercial rubber.

Ericameria nauseosa nicked branchThe leaves and trichomes also contain about 35 percent resin by dry weight. The resin contains aromatic (in the hydrocarbon ring sense, not in the olfactory sense) terpenoid compounds that could be used in manufacturing plastics. Some of the terpenoids may be used as nematicides and insecticides (Finley and Neiland, 2013).

Like nearly every native plant, rubber rabbitbrush is used by several tribes for various purposes. The Navajo use the bright yellow flowers to dye clothing, leather, and crafts. The Hopi also use it as a dye and weave wedding belts with the branches. Dried leaves and flowers are boiled in water to create a soak used to relieve pain and swelling caused by arthritis. Ceremonially, it may be used to treat someone who has been attacked or possessed by an unwanted spirit. Shoshone tradition uses it this way to treat nightmares, but it is rarely mentioned because the treatment can backfire (Clifford, 2019). Ground up stems can be used as chewing gum (Kershaw, 2000). Cottony white insect galls that form on the branches are strung as beads to make a necklace that is hung around babies’ necks to stop their drooling (Curtin, 1997). The galls can also be used to treat toothache and stomach problems (Dunmire and Tierney, 1995). Even if it had no herbal uses, rubber rabbitbrush is a very attractive native plant that deserves to be in High Plains gardens, and if you repeat its name rapidly, you can greatly improve your oratory skills!

Ericameria nauseosa graveolens and E. n. ssp. nauseosus along the roadsideThere is a wide median just outside the Cheyenne Botanic Gardens in the middle of Carey Avenue. Upon arriving in my position as Director, I was told that the City of Cheyenne had a thought that this expanse of turf should become a water-wise landscape with native plants. Of course, rubber rabbitbrush is one of the plants that comes to mind. Its deep root system and ability to withstand high pH and salinity make it one of the few plants that might succeed in this tough spot. The soft, billowy texture created by the fine branching habit and tiny leaves in summer, the stunning and bright yellow flowers that cover the shrub in late summer and early fall, the fluffy seed heads that follow and persist well into winter, and the stunning green stems make it lovely in every season. It is heavily used as a pollen and nectar source by native bee species, because it produces so many flowers when very few plants are in bloom.

Ericameria nauseosa flowers and honeybeeRubber rabbitbrush may grow as tall as six feet. Plant Select® has selected a compact cultivar called Baby Blue that tops out at 28 inches if the species is too tall for you. Because it can recover quickly from hard pruning and blooms on new growth, you can also cut it back nearly to the ground in late winter or early spring to keep it in bounds.

Medicinal Disclaimer: It is the policy of The Herb Society of America, Inc. not to advise or recommend herbs for medicinal or health use. The information in this presentation is intended for educational purposes only and should not be considered as a recommendation or an endorsement of any particular medical or health treatment. Please consult a health care provider before pursuing any herbal treatments.

Photo Credits: 1) Ericameria nauseosa (Creative Commons, Thayne Tuason); 2) Ericameria nauseosa flowers (Creative Commons, Matt Lavin); 3) Ericameria nauseosa foliage (Creative Commons, Matt Lavin); 4) Ericameria nauseosa (Steve Dewey, Utah State University, bugwood.org); 5) Ericameria nauseosa nicked fuzzy branch (Creative Commons, Matt Lavin); 6) Ericameria nauseosa ssp. graveolens and E. n. ssp. nauseosa along the road edge (Creative Commons, Matt Lavin); Ericameria nauseosa flowers and honeybee (Creative Commons, Christopher Gezon).

References

Bowers, J. E. 1990. Natural rubber-producing plants for the United States. Beltsville, MD: USDA,Cooperative State Research Service and National Agricultural Library.

Clifford, A. 2019. Rubber rabbitbrush- native memory project. Accessed February 2, 2023. Available from https://nativememoryproject.org/plant/rubber-rabbitbrush/.

Curtin, L.S.M. (Revised by Michael Moore). 1997. Healing Herbs of the Upper Rio Grande – Traditional Medicine of the Southwest. Santa Fe, NM: Western Edge Press, 1997.

Dunmire, W. and G. Tierney. 1995. Wild Plants of the Pueblo Province. Santa Fe, NM: Museum of New Mexico Press.

Finley, W. F. and L. J. Nieland. 2013. Land of Enchantment Wildflowers: A Guide to the Plants of New Mexico. Lubbock, TX: Texas Tech University Press.

Kershaw, Linda. 2000. Edible & Medicinal Plants of the Rockies. Edmondton, Canada: Lone Pine Publishing.

Ma, D. 2019. A development of natural rubber extraction from Ericameria nauseosa (rabbitbrush) [Unpublished doctoral dissertation] University of Nevada, Reno.


Scott Aker is the director of the Cheyenne Botanic Gardens in Cheyenne, Wyoming. He authored Digging In in The Washington Post and Garden Solutions in The American Gardener.

The Power of One: A GreenBridges™ Story

by Debbie Boutelier

(Editors’ note: This article originally appeared in a recent HSA newsletter. It has been edited for clarity for this post.)

Pipevine swallowtail butterflyIn a recent GreenBridges™ presentation, I mentioned the power of one several times. I’d like to share a short story about how the power of one worked in my GreenBridges™ garden. My garden was certified a number of years ago, and I have been slowly incorporating more native plants into my landscape. (We all NEED a reason to buy more plants, right???) 

When COVID hit, and we all had to stay home more, I decided it was time to kick my garden projects into full speed and actually complete those projects that had been in the planning stage for a while. (I’m not going to admit how long they were in the planning stage, so don’t ask!) I made a pledge to myself at that time that at least 90% of the plant material to finish these projects would be natives. I knew a lot of our local natives, but it was so much fun researching the lesser known species and then actually finding them. 

Monarch caterpillarFast forward to this past spring. When the weather started warming up, I noticed more pollinators busy in the garden collecting nectar from the early blooming plants. THEN, I noticed the number of butterflies that were enjoying my garden. Oh my gosh, for several weeks, I would go out into the garden and literally feel like I was in a butterfly house at a botanical garden! The butterflies swarmed around me as I worked in the beds. It made my heart so happy! I wish I had made a video, but I was living in the moment. There were different swallowtails, gulf fritillaries, skippers, hairstreaks, Eastern tailed-blues, sulfurs, American painted ladies, viceroys, buckeyes, and some I did not recognize. I enjoyed their presence immensely. Even though that period was totally glorious, I still have good numbers of the winged beauties visiting daily. 

Gulf fritillary on buttonbush flowerMy granddaughter and I enjoyed raising swallowtail and gulf fritillary caterpillars this summer. We  released 47 swallowtails and nine fritillaries. The swallowtails slowed down after having eaten every morsel of parsley, dill, and fennel in my garden. I saw more fritillaries at that time of the season as they voraciously attacked the passionvine. By the end of the summer, those vines were leafless, but that’s fine with me. I know they will be back next year to provide for the new generations.

I also need to mention the bees. They have also immensely enjoyed the bounty in the garden. Earlier in the season, my granddaughter and I stood under the Vitex trees while they were blooming and listened to the buzzing. The trees were alive with movement and sound! Even though the Vitex agnus-castus is not native to our country, it is still welcome in my garden for the amount of nectar it provides for the winged visitors.

Bee on Echinacea flowerThough just about over, this has been a spectacular gardening season. I truly believe that each of us can make a difference right where we are. The effort is so worth it!

It is easy to get your garden to be a certified GreenBridges™ garden. The application is on The Herb Society of America website: https://www.herbsociety.org/get-involved/greenbridges-initiative.html  Just answer a few questions and take a few pictures to send with the application. We are actively building green bridges across communities, towns, cities, regions, and the entire country. Let your power of one join with the rest to make a huge difference for our native plants and pollinators.

Photo Credits: 1) Pipevine swallowtail (Alabama Butterfly Atlas); 2) Monarch butterfly caterpillar (Christopher Upton, US National Arboretum); 3) Gulf fritillary (TexasEagle, CC BY-NC 2.0); 4) Bee on Echinacea flower (Christopher Upton, US National Arboretum).


Debbie Boutelier is The Herb Society of America’s GreenBridges™ Chair and HSA Past President. She is an Alabama Advanced Master Gardener and has studied the medicinal uses of herbs for many years, completing a three-year intensive study of the medicinal aspect of herbs at the Appalachian Center of Natural Health. Debbie now teaches nationally and presents seminars and workshops on the many aspects of herbs, organic gardening, nutrition, and other garden related topics. Debbie’s herb passion has led to the creation of her small cottage herb business, Rooted in Thyme Apothecary.

The Least I Can Say about Texas’ Native Bees

by Vicki Blachman, South Central District Member at Large

Honey bee on a yellow flowerThere are over 20,000 bee species in the world.  Of those, close to 4,500 are considered native to the U.S., and up to 1000 are native to Texas (I typically say “over 800”). They’re currently classified into seven families, of which six are represented in Texas. Our native bees range in size from nearly an inch long down to smaller than a peppercorn. I’ve tried to limit the scope of this article to the least I can say given that “the native bees of Texas” is a broad topic well suited to the size of our state.

As for that iconic golden yellow and black striped honey maker, the honey bee (Apis mellifera) is non-native but well established. As described by Michael Engle in 2009, it also appears to have at least one extinct ancestor (A. nearctica) that lived in North America 14 million years ago. Our challenge is that those hairy-eyed honey bees get all the love, and only recently have natives been recognized for their intrinsic value to local biomes and as the workhorses they are. Their PR needs our help.  

Bumblebee on a pink flowerHow many people even know native bees exist? They’ve pollinated every single flowering plant in North America until the 1600s when the honey bee was imported. They’re considered at least three times as effective as honey bees for pollination. Some pollinate plants that honey bees can’t, or pollinate certain crops up to 20 times more effectively. Some, like the bumble bee, are capable of buzz pollination, a technique that honey bees lack. The takeaway? Our native bees have co-evolved over time with native plants to be mutually beneficial and mutually dependent – lose one and the other will be lost as well.   

The terms “native” and “solitary” are often used interchangeably, but not all native bees are solitary, nor are all solitary bees native.  A solitary bee will mate, deposit and provision her eggs, then continue laying eggs until her death four to eight weeks after her own emergence.  Those eggs are left alone to grow and pupate, before emerging the following spring or early summer to repeat the cycle all over again.  It’s often said each solitary bee is her own queen.

By contrast, our native bumble bees are said to be social or semi-social, having the presence of two generations in a single nest at the same time.  Honeybees are called eusocial, or “true” social, due to multiple generations of individuals present, each individual having a specific role to play in the collective hive.

There are solitary bees that are non-native, bees and bee products having been imported freely until a 1922 Honey Bee Importation Law was passed. But that legislation applies to honey bees; solitary bees, which do not produce honey, continue to be imported for research and subsequent commercial use. For example, hornfaced bees (Osmia cornifrons) were first imported from Japan to Utah in 1965, but did not survive. In 1976, they were imported again into Maryland where they still thrive in a climate more like that of their home in central Japan.  The delightfully named shaggy fuzzyfoot bee (Anthophora pilipes villosula) even more recently has been imported from Japan as a managed species for commercial blueberry and other fruit pollination.

Green hollow stem of Oenanthe crocataSome solitary bees will form aggregations where nesting conditions are favorable. While a large number of individuals may be found using the site, only a very few species are actually communal, meaning they actively help each other. Dependent on their environment, the family Halictidae even has the unusual ability to switch between being social or solitary!  

The vast majority of native bees are ground nesting.  Some make cells of mud, bits of leaves or petals, resin, hairy plant fibers, wood dust, cellophane-like secretions applied with their tongues, or silk-like secretions from thoracic glands. These are placed in tunnels in the ground, abandoned rodent burrows, hollow reeds, bamboo, logs, pithy stems, softwood structures, and even holes in bricks or other man-made items such as hand tools and equipment.

Greenish halictid bee on a purple flowerWhile man-made bee houses may have benefits, in order to avoid predation and reduce susceptibility to disease they should be scattered about the site rather than clustered together.  Bee houses should have a guard of chicken wire, or other material with bee sized holes, across the opening to prevent predation by birds. The openings should face the sun in the morning and have protection from rain and insulation from extreme cold if they’re not placed inside to overwinter.  Under the Texas Death Star, it can also be beneficial to have plants growing nearby that provide afternoon shade. Habitats should also include a source of moisture and shelter from wind.  In the fall, “leave the leaves”, as well as stems and grasses, for shelter.

In closing, I repeat the takeaway I’m certain many of you already knew.  Our native bees have co-evolved over time with native plants to be mutually beneficial and mutually dependent – lose one and the other will be lost as well.   

RECOMMENDED RESOURCES:

https://www.fs.fed.us/wildflowers/pollinators/animals/bees.shtml

http://w3.biosci.utexas.edu/jha/landowner-naturalist/texas-pollinator-guides

https://tpwd.texas.gov/huntwild/wild/wildlife_diversity/nongame/native-pollinators/bumblebee-id.phtml

https://bugguide.net/node/view/475348

Photo Credits: 1) Apis mellifera (Ivar Leidus via Wikimedia); 2) Bumblebee (Niek Sprakel, public domain); 3) Osmia cornifrons (Beatriz Moisset via Wikimedia); 4) Cellophane bee emerging from its ground nest (NY State IPM Program at Cornell University); 5) Hollow stems provide nesting sites to solitary bees (Alex Lockton via Wikimedia); 6) Buzz pollination by a halictid bee (Bob Peterson via Wikimedia)