Native Medicinal Plants That May Proliferate with Disturbance Events:
Recent news cycles have been dominated by stories of climate change including floods, extreme heat, and wildfires. Disturbance events such as large-scale and high-intensity fires along with economic land uses like grazing and logging are changing plant communities in many areas of the American West. These events and their consequences have become classic symptoms of this modern era of human-driven change to Earth systems known as the Anthropocene. Many plants are in decline as a result of rapidly unfolding environmental alterations of their habitats, but some native species are showing us that they are finding a way through these changes. In some cases, habitat disturbance could even potentially increase certain species’ populations, facilitate their migration into new territories, or expand their ranges. Here we will explore the hopeful examples of the legendary native medicinal plants arnica (Arnica sp.), oshá (Ligusticum porteri), Oregon grape (Mahonia sp.), red root (Ceanothus sp.), creosote (Larrea tridentata), mesquite (Prosopis sp.), potentilla/cinquefoil (Potentilla sp.), and globemallow (Sphaeralcea sp.). In doing so, we may find models for our own resiliency and new inspiration for our own ability to adapt in a rapidly changing world.
Arnica (Arnica sp.)
There are at least 20 native arnica species in the mountains of the American West. A. cordifolia and A. chamissonis are the most widespread, and the former can sometimes become a dominant understory plant in forested areas and on the edges of open meadows. A. cordifolia is also an important browsing plant for many ungulates and other animals. Although these mountain environments are experiencing dramatic changes related to logging and devastating wildfires creeping up into higher and higher elevations, arnica brings us hope as an example of a species that could adapt to these disturbance events and proliferate despite our expectations. Research has shown arnica species responding positively after forest thinning (Austin 1982), logging (Geier-Hayes 1989), fires (Stickney 1993), grazing, and mowing (Ellenberger 1999; Myklestad and Saetersdal 2004) with an ability to resprout rhizomes and produce a burst of flowers one to two years after disturbance.
It is worth noting that arnica is a widespread plant with a story that expands beyond the American West. A. montana is native to Europe and commonly sold in herbal commerce. It is endangered through much of its range as a result of high-density cattle grazing (Kathe 2006) and agricultural practices with heavy fertilizer use that alters the soil composition in arnica’s native meadows (Michler et al. 2005). While wild populations have been significantly impacted in many countries, some governments are taking action to protect this species. Arnica is also cultivated, albeit with some difficulty. The fates of medicinal plants with ranges that extended across continents must be considered on a species to species level based on different conditions that exist around the globe.
Medicinal Note: Arnica flowers are harvested and commonly used for topical anti-inflammatory and pain-relieving products such as massage oil or salves and creams. Clinical trials have shown arnica to be as effective as ibuprofen for treating osteoarthritis pain and stiffness (Knuesel et al. 2002; Widrig et al. 2007). It is not recommended for internal use due to its propensity for causing severe upset stomach and other negative effects. (Detailed profiles for all of the medicinal plants discussed here can be found in my book The Ecology of Herbal Medicine.)
Red root (Ceanothus sp.)
Red root also has the potential to surprise us with its shrubby resiliency. In the Southwest, one can find C. fendleri and C.greggii in dry open areas of middle elevation mountain and woodlands. These are important foraging plants for many browsing animals, birds, and insects.
They are also excellent for restoration projects as they transplant well, fix nitrogen, and stabilize soil. C. velutinus has a wider distribution across much of the Mountain West and makes its home in open rocky locations or the partial shade of coniferous forests. It is a pioneer species that surges in the years after logging and fires (Francis 2004) and can spread quickly in these disturbed environments. Whether restoring areas after road and housing development projects or reviving the ecosystem after wildfire, red root it a shrub that will readily establish or bounce back to facilitate recovery of the land.
Medicinal Note: Red root tea or tincture prepared from roots is widely used as a treatment for lymphatic stagnancy as it moves fluids into the interstitial spaces for invigoration of vital energy. It also has a tonic effect on the blood as it unstacks clumped blood cells, thereby facilitating the movement of blood through the capillaries and into deeper spaces within the peripheral tissues. These characteristics make it a useful remedy for a variety of conditions including swollen tonsils, sore throats, inflamed lymph nodes, and stagnation in recovery from illness or injury.
Oshá (Ligusticum porteri)
Oshá is a plant of moist meadows and forested areas in montane and subalpine mountain zones of the Southwest and northern Mexico. Having a preference for open areas and setting more seed in these environments, oshá could benefit from disturbance events that reduce shade canopy in these elevations. As forests undergo logging and climate change-induced conversion from forest to shrubland or grassland through bark beetle outbreaks and fires occurring at higher elevations, oshá may have an increased ability to expand its range or move into new territories. Additionally, oshá, like many other plants, is known to produce differing levels of medicinal constituents in different habitats. For example, distinct chemotypes in populations have been observed in Colorado, with Front Range samples containing more than twice as much (Z)-ligustilide (a major medicinally active constituent) than those from the Western Slope (Smith et al. 2018). Plants that prefer these new conditions and those that will be able to migrate as environmental change unfolds, have the potential to evolve and thrive as disturbance events accelerate in the coming decades.
Being a widely regarded root medicine of popular demand and one that is notoriously difficult to cultivate, much has been written about conservation concerns. United Plant Savers has put oshá on its “at risk” list. Herbalists including Michael Moore (2003) have suggested using other Ligusticum species as substitutes. I have also proposed using herbs such as Grindelia squarrosa, Salvia officinalis, and Monrarda fistulosa, among others as sustainable and effective replacements in formulas (Saville 2001). While concerns about commercial wild harvesting are real, oshá continues to surprise us with its resiliency and its ability to rebound from rhizomes after harvest. One recent study by Kindscher et al. (2019) showed rapid recovery of wild stands when harvesting rates remained at or below 33%. Herein lies an encouraging invitation to steward wild populations through respectful and ethical harvesting practices.
Medicinal Note: Oshá, one of the legendary medicinal plants of its native range, is perhaps best known as a remedy for the respiratory system where it has potent bronchodilation and expectorating actions. Roots are prepared in numerous ways including for tincture, syrup, elixir, essential oil, powders, smoke, infused honey, or simply chewed. It is also commonly called upon for a variety of early stage infections and wound care due to its antimicrobial, anesthetizing, and detoxifying effects. Additionally, oshá is useful as a warming, stimulating, and nourishing treatment for the digestive system.
Oregon grape (Mahonia sp.)
There are a number of Mahonia species ranging across the Western United States including the understory groundcover species M. repens and the larger shrubs M. fremontii, M. haematocarpa, M. aquifolium, and others. M. repens is known to respond positively to disturbance events such as fires and logging, often resprouting from deeply rooted rhizomes and increasing
in density with the additional sunlight. Many Mahonia species are useful for restoration of damaged wild lands due to their propensity for spreading on dry rocky slopes, thereby controlling erosion as the area recovers. Additionally, Oregon grape species are important ecologically as their leaves and berries provide forage for a variety of animals. As forest conversion events become more frequent, we could find Mahonia proliferating and contributing to land resiliency in some areas.
Medicinal Note: Although Oregon grape roots are most commonly tinctured for use as a natural antibiotic or antifungal, it has a number of other important uses. Eclectic physicians indicated it for dry scaly skin conditions (eczema, psoriasis, acne) due to its ability to improve digestion, simulate liver functions, and clear toxins from the blood. Extensive scientific research supports Orgon grape’s antimicrobial activity and clinical trials back up it use for chronic inflammatory symptoms of psoriasis. Ethnobotanical documentation and research have also illuminated numerous other uses for Oregon grape.
Creosote (Larrea tridentata)
An evergreen woody shrub found in all the major deserts of the Southwest and Mexico, Creosote has been successfully expanding its range and density in the landscape over the last century or longer. Although present in the region for millions of years, it was a low-density member of the native plant community for most of its existence. Early American travelers through the Chihuahuan Desert during the 1800s described “hundreds and hundreds of thousands of acres, containing the greatest abundance of the finest grass in the world” (Gardner 1951:382) without a single mention of creosote until the botanist Charles Christopher Parry listed the shrubs of the area in 1859. Yet, today creosote is an indicator plant for the Chihuahuan Desert and a dominant member of the plant community, often forming vast expanses of near monoscapes. Botanical surveys of the 20th century (e.g. Gardener 1951; Gibbens et al. 2005; Humphrey and Merhoff 1958) have documented the proliferation of creosote in New Mexico and Arizona, illuminating this plant’s successful adaptation strategies in the face of significant environmental degradation.
Often described in economic terms as an invasive species, this native plant is responding to land exhaustion caused by widespread overgrazing on marginal arid grasslands (Fleischner 1994; Whitfield and Anderson 1938; York and Dick-Peddie 1969, and others). As cattle grazing became a dominant land use in the region, numerous effects upon the land and plant communities have become apparent. These include the reduction of species richness and declines in the density and biomass of individual species; interference in ecosystem functions, including the destruction of cryptobiotic crusts that fix nitrogen, increase organic matter and phosphorus, stabilize soil, increase water filtration, and provide germination locations for seeds; and alteration of ecosystem structure by affecting soil composition and water availability, leading to erosion, soil compaction, reduced water filtration, and desertification (Fleischner 1994). Such alterations are advantageous to Creosote and have substantially aided its proliferation over the last century (Gardner 1951; Gibbens et al. 2005; Humphrey and Mehrhoff, 1958).
Economic land use converging with endogenous adaptations and climate change have already helped Creosote to expand its population and this trend will likely continue in the future. As Creosote establishes itself on bare soil created by grazing, it furthers its hold upon the land through an allelopathic root chemical (NDGA) that enables the plant to maintain a low root density in the soil and maximum water availability for itself (Elakovich and Stevens 1985; McAuliffe 1988). Additionally, Creosote roots change the land to impair soil stability and electrical conductivity while reducing calcium and nitrate, making it more difficult for annuals to grow in its vicinity (Whitford et al. 2001). Increasing heat and long-term drought will undoubtedly negatively impact other plant species and may shift further advantages into hearty and enduring Creosote’s court.
Medicinal Note: A highly valued purifying herb in traditional herbal practice of the region, creosote has many practical applications as a topical and short-term internal remedy. Due to its stimulating effect on the liver, which contributes to its anti-inflammatory effects, it is not recommended for long-term internal use and is therefore often prepared as a topical soap, oil, salve, or liniment. This trait combined with its potent antimicrobial and aromatic effects makes it a good choice for wound care, a wide array of tenacious infectious organisms, and conditions of stagnancy including arthritis and respiratory congestion. Harvest leaves primarily, but also flowers, seeds, and twigs.
Mesquite (Prosopis sp.)
Mesquite, a common shrub of desert grasslands and shrublands, is another native plant that is expanding its range and density in regional landscapes. This genus includes several species and varieties including P. glandulosa (honey), P. pubescens (screwbean), and P. velutina (velvet). These are important ecologically for providing forage and cover for as many as thirty-eight bird species and also help to create critical desert migration corridors for wildlife. As with creosote, historical landscape descriptions and botanical surveys over time have shown a dramatic increase in populations over the last 150 years (Brown and Archer 1987; Buffington and Herbel 1965). The effects of grazing, described above with creosote, have contributed to mesquite’s expansion as cattle eat the nutritious bean pods and excrete them in fertilizer, assisting with their propagation in grasslands. Mesquite is also highly adapted to drought. Shrubs commonly have forty-foot-long taproots if there is subsurface water. The longest recorded roots reached 190 feet (Sosebee and Wan 1989). In areas with no subsurface water source, mesquite can grow lateral roots up to sixty feet from its center (Sosebee and Wan 1989). As economic land uses, prolonged drought, and rising temperatures intensify their effects upon the land, resilient shrubs like mesquite have an opportunity to hold their place in the landscape and perhaps even continue their advancement into new areas where scarce water and ecosystem degradation make it difficult for other native plants to grow.
Medicinal Note: Leaves, seed pods, and bark are used for medicinal preparations when an astringing antimicrobial is indicated. But the most significant role of mesquite is as a nutritive food that helps to regulate critical body functions. Mesquite was one of the most important sustaining wild foods for Southwestern people, much like piñon for dwellers of the Colorado Plateau. Seeds and pods contain protein, carbohydrates, fat, fiber, amino acids, and various minerals and they can be ground into flour and made into a wide variety of foods and fermented beverages. As a healing food, research supports mesquite’s ability to regulate blood sugar and cholesterol, giving it potential to moderate common lifestyle-related ailments of the modern era through the rekindling of our regional culinary traditions.
Potentilla/cinquefoil (Potentilla sp.)
Impressively adaptable and diverse, there are about fifty-seven native species in the western states. This multitude of species make their homes in a wide array of habitats including forest, woodlands, sagebrush flats and grasslands. In these areas potentilla plants provide important sources of forage and cover for numerous animals from browsing ungulates to small mammals. Some of these species including P. glandulosa are known to establish or spread as a result of disturbance events such as fires, grazing, and logging. As these land uses continue and wildfires increase in frequency across the western United States, potentilla may have opportunities to survive landscape changes and possibly even increase its population. Additionally, it may get an extra boost in establishment in new areas as it may have allelopathic activity to help suppress seed germination of other species, thus providing advantages in migration. Plants such as potentilla that are diverse and numerous in species, accepting of a variety of habitat types, adaptable in migration strategies, and resilient in the face of land alteration, give us reason to hope that native plants may be able to navigate the coming decades of change that are instore.
Medicinal Note: As a rose family member, potentilla has a similar history of use in formulas where cooling, drying, anti-inflammatory, and antimicrobial actions are useful. Leaves and flowers are prepared in numerous ways for wound healing, oral health care, respiratory, and digestive uses as well as skin and hair products. Scientific research adds important new potential applications for potentilla in cancer prevention and treatment and in the immune system through its ability to increase production of T-lymphocytes and white blood cells.
Globemallow (Sphaeralcea sp.)
Most Sphaeralcea species are associated with the hot dry conditions of the Southwest but you will find the more compact S. coccinea growing across the western and plains states. Many of these species readily cross-hybridize, making species identification somewhat tricky. Globemallows bloom in harmony with desert bees that form a symbiotic relationship of forage and pollination. S. coccinea is also known to support a wide array of wildlife from browsing animals to small mammals, birds, and insects and is therefore an important plant ecologically. Globemallows are not picky about soil types and are very drought tolerant, making them very adaptable and enduring in a variety of landscape conditions. Additionally, they spread by rhizomes and establish easily in disturbed soil protecting against erosion and adding resiliency to areas that have experienced wildfire or land conversion. Globemallow is a top pick for restoration projects in many environments including short-grass and mixed-grass prairies, piñon-juniper woodland, and sagebrush ecosystems. With a combination of character traits and adaptations that facilitate its survival in areas characterized by heat, drought, and wildfire disturbance, and an ability to thrive in a variety of habitat types, Globemallow is the medicine of our times, both for land health and human health. This is a plant that mitigates inflammation in the land and our bodies.
Medicinal Note: Globemallows have been widely used by ancient and modern people of the Southwest and other areas, who harvest leaves, flowers, and roots primarily for water-based extractions. Cooling, moistening, and healing to soft tissue, globemallow is an excellent remedy for dry cough, sore throat, heartburn, and other conditions of hot dry inflammation. Additionally, it is an effective immune-balancing herb, making it a top treatment for both auto-immune conditions as well as for those with sluggish immune response. This combination of traits along with regional abundance, makes globemallow one of the most used herbs in my apothecary.
The native medicinal plants described here have many things in common. They have long supported, nourished, and healed human and animal populations wherever they have grown. These plants have also contributed to critical ecological functions and protected the land as economic exploitation and land conversion have drained the resiliency of vast expanses of their native ranges. They have developed brilliant ways of knowing how to survive despite the threats posed by rising heat, dwindling water availability, and wildfire devastation. They are finding ways to align with current conditions and proliferate despite difficult conditions. These plants serve as inspiring examples of how species might use their innate abilities or evolve to meet the challenges of changing times.
Of course, the future can never be certain. Climate changes could unfold more rapidly and more dramatically than current modeling suggests. The exhaustive economic land uses, escalating heat-driven drought, and devastating wildfires of our current era are all phenomena with the potential to create change that remains beyond the intellectual acceptance and imaginations of many. And if these patterns continue to accelerate, it may push innumerable species beyond the limits of their adaptability. The species discussed, here, however, are offering us a beacon of hope as we grapple with spiraling alterations to earth’s systems. These species are offering lessons not only in resiliency and adaptability, but also a warning. There is no time to lose. We must take meaningful and sweeping actions to avert further degradation of habitat, loss of species, and threats to our own existence. We must de-center ourselves and re-center life, redefining this era we call the Anthropocene.
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