By Scott Aker
It 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.
Fast 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.
The 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.
I 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.
The 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!
There 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.
Rubber 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 mention of our neighbor to the south typically conjures up images of sunny beaches, arid deserts and plateaus, a rich cultural history, delicious cuisine, and of course tequila. So, on a recent trip to Mexico City it came as no surprise to see the landscape dotted with agave, cacti, and various shrubs, growing ever more frequent as we slowly made our way out of the bustling city and toward Teotihuacan. It was here, at a well-established tourist outpost just outside of the ruins, that we were introduced to the many uses of the agave that can be found all over the area.
Most notably to us, agave is the main component in the production of tequila or mezcal. At Teotihuacan, visitors are able to enjoy a tasting tour through the various spirits that can be made from agave. We began by tasting pulque, a “non-distilled traditional alcoholic beverage produced by the fermentation of the [agave] sap known as aguamiel” (Escalante et al., 2008). This sweet, viscous, milky drink had a mild sugariness that was very pleasant, with the texture of a smoothie I had made in my blender at home. We then moved on to sampling some mezcal, a liquor that is much more similar to the tequila that many are familiar with, with one important distinction. Katie Robbins at Delish (Robbins, 2021) states that “while mezcal can be made from a blend of one of 250 types of [agave] to be classified as tequila, a bottle must be at least 51 percent blue agave (
Though there are many species of agave in cultivation, there are a few species (notably 
These plants can also provide other sorts of products from different methods of harvest. The sharp prickles that grow at the end of agave leaves can be used as a needle, in conjunction with the sisal thread, to sew together pieces of sisal textile. The uppermost layers of the leaves can be used as a sort of paper, once peeled off into a thin, flexible sheet. A paper can also be made by pressing the pulp of the agave plant, in a manner more similar to that of paper production with woody pulp.
Efforts are being made to restore the historic levels of sisal production in Mexico, as well as globally, in a bid to combat the increased dependence on synthetically produced fibers. Through groups like the Food and Agriculture Organization of the United Nations, emphasis is being placed on building sustainable production mechanisms that can satisfy global demand with a supply of natural sisal fiber. 
I fully admit to living under a rock. Many a friend and coworker has informed me of this character “trait.” Because I am not so worldly as others, I learn things by more circuitous routes. For example, my latest herbal discovery resulted from watching a recent episode of The Great British Baking Show. George, one of the bakers, remarked that he was including mastic in his bake. Of course, Paul Hollywood, one of the show’s hosts, commented with raised eyebrow, “A little mastic goes a long way.” George returned fire, stating, “You can never have too much mastic!” Clearly, mastic was near and dear to this Greek baker’s heart.
Mastic is a resin extracted from Pistacia lentiscus cv. Chia L. (Chios mastictree, mastic), which is a member of the Anacardiaceae family (GRIN-Global; Browicz, 1987). (Cashew, Anacardium occidentale L., and pistachio, Pistacia vera L., are also members of this family.) This small shrubby tree is native to numerous countries around the Mediterranean, from southern Europe to northern Africa to western Asia (Sturtevant, 1919), but it is most notably—and historically—linked to the Greek island of Chios in the northern Aegean Sea, about nine miles west (the way a crow flies) of the Turkish 
constituting the main source of income for approximately twenty villages in the south of Chios” (Browicz, 1987). The trees reach their full height after 40 – 50 years, but harvesting reaches its full potential after 12 – 15 years (FAO, 2021). Similar to frankincense (Boswellia spp.) and myrrh (Commiphora spp.), the mastic harvester nicks the tree bark to produce “tears,” or droplets, of resin, which then harden and are scraped off. These hardened blobs of resin are gathered and taken for processing (masticlife.com).
If you haven’t picked up on the etymological relationship by now, translated from the Greek, mastic means “to gnash the teeth,” or in modern parlance, to chew or masticate…an appropriate term for the gummy treasure. Spurred on by the mention of it on The Great British Bake Off, I was on the hunt for this chewy, new-to-me herb. Fortunately, we have a husband-and-wife team of volunteers in the National Herb Garden, who just happened to live in Greece for a number of years. What better resource than these two to probe for information—outside of knowing a native of Chios, of course.
They confirmed that mastic was, indeed, a ubiquitous flavoring in parts of Greece, including its use in mastika, a sweet liquor flavored with the resin (something else I had never heard of before) and ouzo, another Greek spirit. They said that you can find mastic gum and Turkish delight-esque candies all over Chios (well, in Greece, generally, and also in surrounding areas), as well as in well-appointed Mediterranean markets, even in the United States. I asked them what it tastes like, and they both hemmed and hawed trying to find the right words to describe its unique flavor. I immediately assumed it would be “pine-y” or “camphor-y” or something of the sort, since it is a tree resin, after all, but they both still hemmed seeming to suggest that it wasn’t exactly that strong. 
They were right: not exactly pine-y, but not exactly anything else either. I moved the candy around in my mouth trying to find words to describe it. Yes, it certainly had resinous, “pine-y” kinds of notes, but it also had a bit of a flowery essence to it. It was certainly unlike what I was expecting. Not nearly as strong as I thought it would be, but also not without character.
Speaking of other herbal uses, mastic is also found in perfumes, personal hygiene products, and medicines. The resin has been used for centuries as a component of incense, particularly for the production of “moscholivano, [which] is a solid essence that, when burned, releases a pleasant odour” (FAO, 2021) and as an ingredient in chrism, the anointing oil used in the Eastern Orthodox Church (and others). In The Perfume Book, 
If you thought this story was over…not so fast. Mastic has a few more tricks up its sleeve. Mastic is used as a component of dental fillings, in dentifrices, and mouthwashes, helping to knock down pesky bacteria in the mouth. It should also be noted that “thanks to its quality as a colour stabilizer, mastiha is used for the production of high-grade varnishes” (CGMGA), such as those used in oil painting (megilp), and as a protective coating on photographic negatives. Rosin, a by-product of gum mastic’s distillation process, is used in myriad industries as well.
As an aside, Alexandra Rodrigues and associates inoculated newly created stained glass samples with fungi previously isolated and identified on original stained glass windows. They found that “fungi produced clear damage on all glass surfaces, present as spots and stains, fingerprints, biopitting, leaching and deposition of elements, and formation of biogenic crystals” (Rodrigues et al, 2014). Let that be a warning to keep your stained glass windows clean. 
One of the more interesting lichens is known as Icelandic moss (
Have you heard of St. John’s bread or locust bean? These are all names for the carob tree, 
Carob pods discovered in the storehouses of Pompeii show that the Romans were harvesting the tree as early as 79AD. The Romans ate the carob seeds for their sweetness. The Greeks used carob pods as fodder for their pigs and food for their people.
Recent research shows that carob powder is a rich source of the antidiabetic compound D-pinitol, a type of sugar. D-pinitol can decrease blood sugar levels and prevent obesity by suppressing the increase in human adipose tissue. In addition, the polyphenols in carob fiber have been shown to inhibit cell proliferation in some cancers (Loullis, 2018).
One of my friends is a complete and total railroad aficionado. I love these kinds of people because they often have gems of obscure information at the ready for anyone willing to listen, and as a naturally inquisitive person myself, I am almost always a willing listener. Recently, this friend–I’ll call him James–was explaining to me the wheel systems on trains, pre-21st century. (I told you it was obscure, but I love it!). Midway through his explanation, he said, “And they packed the journal [part of the wheel system] with cotton waste, and…”
“Where did they get it? Did they just tear up old shirts or something? That’s a lot of old shirts for all the trains in the country!”
I was so excited to learn about this use of cotton–as obscure as it may be to most of us–because cotton (Gossypium hirsutum) is one of my favorite herbs! The fibers are used in so many applications, it’s hard to recount them all: from clothing (the obvious) to cotton swabs/balls to movie film cellulose (now a thing of the past); from cling film to its use in the food industry (cottonseed)… these are just a few examples. Talk about a jack-of-all-trades. And here was yet another use for this amazing plant: the inner workings of a train. Who knew?! James did, of course.
flammable material laying about (a whole other topic). But as it turns out, there are various companies and non-profit organizations that collect the waste–either the fabric or fiber–and recycle it into things like new garments, furniture, or housing insulation. (You gotta admire people’s ingenuity.) According to one insulation manufacturer, their insulation is fire-retardant, mold/mildew resistant, has no VOCs (volatile organic compounds), and has excellent noise-dampening qualities. While I cannot speak to the veracity of those claims, the mere idea that cotton fiber can be used in a different format, yet again, is a perfect example of what it means for a plant to be “herbal.”
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